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INTERNATIONAL SEMINAR ON DISINFECTION WITH MIXED OXIDANTS GENERATED ONSITE PAHO LIMA, PERU DECEMBER 5 - 1 2 1987 Li[?r:.*.r:Y. tf:7r.F.r,/v.:-:::"A'.. rvzFEriENCE CE :::lt[ A - - : ; ; ;:.-\ y~\ .. <.••':•:.:•.:. ..-'•i-.yA'.V.'Zs • . .; . . : ) :; P.C. £>•.:. v.-<-.. . 1::;09 AD The I U-.g'is Tel. iGVO) 8 ; « i j i : ext. 141/142 f?N: * ^ LO: !i »•• " U f r * L Y :' 2^.^ M ' ^ "~ ;: I > THE JOHNS HOPKINS v.f UNIVERSITY SCHOOL OF MEDICINE rlcasc mldicss reply tare of Dt:rA R 7 MEN T OF PI.OIA IRICS Division of Infectious Till: JOHNS HOrKINS 1IOSPITA L RAUIMORE. MARYIAND21205 Phrases Baltimore, June 29 , 1987 Doctor • DONALD S. SHARP Associate Director Water Supply and Sanitation Health Sciences Division International Development Research Center (IDRC) P.O. Box 8500 Ottawa, Canada KIG - 3H9 Dear Doctor Sharp: Thank you f o r sending me the g u i d e l i n e s and a p p l i c a t i o n forms for r e s e a r c h s u p p o r t and general i n f o r m a t i o n about IDRC. We appreciate your encouragement and support in our research e f f o r t s . As I t o l d you on the phone, P r o f e s s o r M a r i a Yolanda Ramirez and I , have d e c i d e d t o c o n t i n u e w i t h t h e r e s e a r c h a c t i v i t i e s and the m u l t i d i s c i p l i n a r y group that we established a few years ago in C a l i , Colombia, w h i c h i s based at t h e U n i v e r s i t y o f V a l l e . Under our leadership, the group involves research workers from the School of E n g i n e e r i n g and t h e School o f M e d i c i n e and H e a l t h Sciences at the U n i v e r s i t y , as w e l l as from the Cali Regional Health U n i t , which is t h e branch o f t h e M i n i s t r y of H e a l t h i n C a l i . We are i n t h e process of f o r m a l i z i n g a j o i n t program between the U n i v e r s i t y of Valle and the Johns Hopkins U n i v e r s i t y , f o l l o w i n g our research experience f o r the l a s t two years at Johns Hopkins. We are proposing a whole package of i n v e s t i g a t i o n s in the area of d i a r r h e a l d i s e a s e s and e n v i r o n m e n t a l h e a l t h , to be accomplished in the next f i v e years. Our plan consists o f the f o l l o w i n g s t u d i e s : 1. The f i r s t study w i l l evaluate an oxidant generator which the Pan American H e a l t h O r g a n i z a t i o n (PAHO) i s w i l l i n g t o i n t r o d u c e i n s m a l l c o m m u n i t i e s o f d e v e l o p i n g c o u n t r i e s . The PAHO d e v i c e , which d i s i n f e c t s b a c t e r i a , v i r u s e s and p a r a s i t e s , should improve the q u a l i t y of the water supplies of such populations, which do not have access to a r e a l aqueduct. net. \\This study w i l l be submitted f o r funding t o PAHO and w i l l be conducted in C a l i , Colombia. 2. The second study w i l l e v a l u a t e two s i m p l e methods f o r i m p r o v i n g w a t e r q u a l i t y , and t h e r e b y i m p r o v i n g c h i l d h e a l t h , i n periurban communities i n C a l i , Colombia. We w i l l evaluate the d i s i n f e c t i o n potential of a simple slow sand f i l t r a t i o n system and the on s i t e o x i d a n t g e n e r a t o r d e v i c e by themselves and both t o g e t h e r a g a i n s t a n a t u r a l n o n - t r e a t e d v/ater supply. Water s u p p l i e s w i l l be examined f o r m i c r o b i o l o g i c a l and p a r a s i t o l o g i c a l q u a l i t y . P a r a l l e l to the water i n t e r v e n t i o n s , we w i l l measure the health impact of these water treatments, among c h i l d r e n from 6 t o 18 months o f age. Fecal c o n t a m i n a t i o n i n d i c a t o r s and s p e c i f i c pathogens w i l l be q u a n t i f i e d at the stages o f i n g e s t i o n , i n f e c t i o n and e x c r e t i o n . D i a r r h e a l disease r a t e s w i l l a l s o be measured. This is the study t o be submitted to IDRC f o r funding. Besides our m u l t i d i s c i p l i n a r y group, which i n v o l v e s , s a n i t a r y engineers, microbiologists, virologists, immunologists, epidemiologists and p e d i a t r i c i a n s , we w i l l have two consultants : Dr. V i n c e n t P. O l i v i e r i , from t h e Environmental H e a l t h E n g i n e e r i n g D i v i s i o n , and Dr. S t e v e n A. E s r e y , f r o m t h e D e p a r t m e n t o f I n t e r n a t i o n a l Health, The Johns Hopkins University School of Hygiene and Public Health. In about two weeks I w i l l send you a pre-proposal describing the two- year s t u d y , which we p l a n t o s t a r t by June 1988. The f i r s t s i x months w i l l be d e d i c a t e d t o p r e l i m i n a r y s t u d i e s , then another s i x months f o r e s t a b l i s h i n g t h e i n t e r v e n t i o n s , p l u s s i x months o f e v a l u a t i o n and s i x months f o r data a n a l y s i s and p u b l i c a t i o n . The p r o j e c t w i l l be performed i n periurban communities t h a t do not have access t o t h e C a l i ' s main w a t e r supply or aqueduct. Our r e s e a r c h group has been working i n four o f these communities and a summary of the s t u d i e s , i n f i n a l form, w i l l be submitted f o r p u b l i c a t i o n in the PAHO B u l l e t i n , 3. A t h i r d study w i l l focus on behavioral changes as preventive measures o f the Acute D i a r r h e a l Diseases Syndrome. This p a r t i c u l a r p r o j e c t w i l l deal w i t h i n t e r v e n t i o n s r e l a t e d t o e x c r e t a d i s p o s a l , personal hygiene and food hygiene. We are considering several sources of funding f o r t h i s study. 4. This w i l l be a v i r o l o g i c a l , b a c t e r i o l o g i c a l and immunological study which w i l l include epidemiologic s u r v e i l l a n c e , d i s t r i b u t i o n , a t t a c k r a t e s , f l u c t u a t i o n s e t c , o f the l e a d i n g pathogens o f the e n t e r i c t r a c t i n some s p e c i f i c areas of C a l i , w i t h emphasis on Rotavirus. Immunological studies of the community from the point of view of the respdnse to Rotavirus i n f e c t i o n plus the i n t r o d u c t i o n and development o f r'apid d i a g n o s t i c l a b o r a t o r y t e c h n i q u e s and some p r e l i m i n a r y studies on the molecular biology of these v i r u s e s , w i l l also be considered. \ This p r o j e c t w i l l be submitted to "Colciencias", the main Colombian governmental i n s t i t u t i o n for research funding. 5. Based i n the p r e v i o u s study we w i l l p e r f o r m a R o t a v i r u s vaccine t r i a l i n C a l i . For such a study we may go t o NIH for funding or possibly to WHO. As you can see, we want to have all research pieces together, in order to evaluate these different interventions as preventive measures of the Acute Diarrheal Disease Syndrome, under the ecological parameters of our developing country. Finally, I plan to contact your representative in Bogota, before sending you the pre-proposal, in order to follow the appropriate channels. Thank you in advance for your patience and reviewing this outline. I would appreciate any suggestions or comments you may have at this time. Sincerely yours, /c.c. c.c. c.c. c.c. Prof. Dr. Dr. Dr. \ Maria Yolanda Ramirez Vincent P. Olivieri Steven A. Esrey Silvio Gomez J. WORKING «' DRAFT DISINFECTION WITH MIXED OXIDANT GASES G E N E R A T E D ON SITE ( M O G G O D ) A Progress Report of the P A H O D e m o n s t r a t i o n - D e v e l o p m e n t December 1987 Project v () /7p JfrLc<4^ SYNOPSIS 9 m In 1982 T h e P a n A m e r i c a n H e a l t h O r g a n i z a t i o n ( P A H O ) h e g a n p r o m o t i n g the d e v e l o p m e n t of t e c h n o l o g y for o n - s i t e g e n e r a t i o n of mixed o x i d a n t s for the d i s i n f e c t i o n of d r i n k i n g w a t e r s u p p l i e s for smell a n d / o r r e m o t e c o m m u n i t i e s in L a t i n A m e r i c a and the C a r i b b e a n . For b r e v i t y t h i s t e c h n o l o g y w a s g i v e n the a c r o n y m of M O G G O D , the term w h i c h will b e u s e d t h r o u g h o u t t h e r e m a i n d e r o f t h e a r t i c l e The f u n d a m e n t a l r e a s o n for P A H O ' s i n t e r e s t in d e v e l o p m e n t of a n e w d i s i n f e c t i o n t e c h n o l o g y w h e n so m a n y c o n v e n t i o n a l m e t h o d s and " a p p r o p r i a t e t e c h n o l o g i e s " a l r e a d y e x i s t e d w a s for the s i m p l e statistical f a c t that m o r e t h a n 757. of all d i s i n f e c t i o n f a c i l i t i e s in L a t i n A m e r i c a and t h e C a r i b b e a n h a v e f a i l e d to p r o v i d e c o n t i n u o u s and a d e q u a t e d i s i n f e c t i o n in s p i t e of m o r e t h a n 2 0 y e a r s of e f f o r t s to d e v e l o p h u m a n r e s o u r c e s , i n s t i t u t i o n s and s u p p o r t i n g infrastructure. T h e b a s i c c o n c e p t b e h i n d t h i s i n i t i a t i v e is to u s e high level t e c h n o l o g y to d e v e l o p s i m p l e , p r a c t i c a l but e f f e c t i v e d i s i n f e c t i o n m e t h o d s w h i c h a r e t a r g e t e d at r e m o v i n g the r e s t r i c t i o n s and p r o b l e m s p e c u l i a r to L a t i n A m e r i c a t h a t h a v e p r e v e n t e d conventional disinfection from being carried o u t . In D e c e m b e r 1986 P A H O w i t h a 20'/. c o n t r i b u t i o n from U N D P i n i t i a t e d the first p h a s e of a d e m o n s t r a t i o n p r o j e c t to i n t r o d u c e a g e n c i e s and i n s t i t u t i o n s of P A H O m e m b e r c o u n t r i e s to the M O G G O D c o n c e p t and to e n l i s t their s u p p o r t in t h e d e v e l o p m e n t o f M O G G O D t e c h n o l o g y . It included the p u r c h a s e of M O G G O D p r o t o t y p e s a l o n g w i t h their s h i p m e n t to p a r t i c i p a t i n g c o u n t r i e s in L a t i n A m e r i c a and t h e C a r i b b e a n for l a b o r a t o r y as well as f i e l d t e s t i n g u n d e r the a c t u a l c o n d i t i o n s w h i c h h a v e led to t h e f a i l u r e o f e x i s t i n g c o n v e n t i o n a l m e t h o d s of disinfection. It is a n t i c i p a t e d that the o p e r a t i o n a l e x p e r i e n c e which is u n d e r w a y will n o t o n l y f a m i l i a r i z e t h e w a t e r supply s e c t o r with M O G G O D t e c h n o l o g y b u t also will lead to a c c e l e r a t e d i m p r o v e m e n t s and a p p l i c a t i o n of the d e v i c e s . The a m b i t i o u s o b j e c t i v e of d e v e l o p i n g i n n o v a t i v e d i s i n f e c t i o n t e c h n o l o g y in the c o n t e x t of L a t i n A m e r i c a a p p e a r s p o s s i b l e in light of the i n c r e a s e d s c i e n t i f i c k n o w l e d g e and m a n y t e c h n i c a l a d v a n c e m e n t s m a d e in r e l a t e d a r e a s o v e r the p r e v i o u s d e c a d e . The project's rapid f e e d b a c k of o p e r a t i o n a l e x p e r i e n c e f r o m t h e u s e r s to the d e v e l o p e r s h a s a l r e a d y r e s u l t e d in a c o n s i d e r a b l e n u m b e r o f s i g n i f i c a n t i m p r o v e m e n t s in d e s i g n , m e t h o d o l o g y and t e c h n o l o g i c a l u n d e r s t a n d i n g . M O G G O D d i s i n f e c t i o n to d a t e h a s b e e n a\t least a s e f f e c t i v e a s c h l o r i n e in b o t h the f i e l d and the l a b o r a t o r y . At this e a r l y s t a g e of the p r o j e c t the r e s u l t s h a v e b e e n "very e n c o u r a g i n g and d e f i n i t e l y - 8 - merit continuation BACKGROUND of AND P R O J E C T the effort. JUSTIFICATION: A l t h o u g h m a n y of t h e small towms and c o m m u n i t i e s of L a t i n A m e r i c a a n d t h e C a r i b b e a n h a v e b e e n served with c o m m u n i t y w a t e r s y s t e m s and m o s t n a t i o n a l p l a n s a i m at increasing t h e w a t e r s u p p l y c o v e r a g e in s m a l l and rural c o m m u n i t i e s , the d i s i n f e c t i o n of t h a t w a t e r h a s b e e n n e i t h e r a d e q u a t e nor r e l i a b l e ; more o f t e n t h a n not it is not e v e n carried out. In P A H O ' S w o r k s h o p in May 1 9 8 ^ for the i n t r o d u c t i o n of the n e w W H O G u i d e l i n e s for Drinking W a t e r Q u a l i t y a p a r t i c i p a n t s u r v e y i n d i c a t e d t h a t m o r e than 75*/. o f the w a t e r s y s t e m s in L a t i n A m e r i c a and the C a r i b b e a n w e r e either i n a d e q u a t e l y d i s i n f e c t e d or not d i s i n f e c t e d at a l l . S u b s e q u e n t s t u d i e s and i n v e s t i g a t i o n s i n d i c a t e a s o m e w h a t h i g h e r p e r c e n t a g e of f a i l u r e . T h i s is o n e of the m o s t s e r i o u s p r o b l e m s a f f e c t i n g the h e a l t h of the r e s i d e n t s of s m a l l t o w n s , rural a r e a s and m a r g i n a l u r b a n a r e a s . T h e i m p o r t a n c e of w a t e r d i s i n f e c t i o n h a s b e e n p r o v e n in b o t h theory and p r a c t i c e . It is a f u n d a m e n t a l p u b l i c h e a l t h m e a s u r e and w h e r e v e r it h a s b e e n c a r r i e d o u t r e l i a b l y and a d e q u a t e l y h a s a s s u r e d h e a l t h b e n e f i t s for the u s e r s of the water s u p p l y . T h e r e are m o r e that 2 0 d i s e a s e s r e l a t e d to d r i n k i n g water s u p p l y . All of t h e m a r e d e b i l i t a t i n g and s o m e a r e d e a d l y , p l a c i n g a t e r r i b l e h a n d i c a p and e c o n o m i c b u r d e n o n e v e r y o n e but p a r t i c u l a r l y u p o n t h e p o o r p e o p l e who least c a n a f f o r d i t . T h e most s e r i o u s a n d n u m e r o u s of t h e s e d i s e a s e s c a n to a very l a r g e e x t e n t be p r e v e n t e d t h r o u g h a d e q u a t e di si n f e c t i o n . T h e r e h a v e b e e n n u m e r o u s s t u d i e s o v e r t h e p a s t 5 0 y e a r s o n the b e n e f i t s of d i s i n f e c t i o n but two of the m o s t r e c e n t are of p a r t i c u l a r s i g n i f i c a n c e to t h i s p r o p o s a l . In their " S t u d i e s o f D i a r r h e a in G u i n d i o C o l o m b i a : P r o b l e m s Related to W a t e r T r e a t m e n t " D o c t o r s David B e r s c h and M a r g a r i t a O s o r i o disclosed an i n v e r s e r e l a t i o n s h i p b e t w e e n the level of r e s i d u a l c h l o r i n e and the r a t e s o f d i a r r h e a a m o n g c h i l d r e n u n d e r 5 y e a r s of a g e . In a p i l o t p r o j e c t in 1981 f i n a n c e d by U N I C E F and c o n d u c t e d by the I n s t i t u t e o f C h i l d H e a l t h i^n C a l c u t t a India in W e s t B e n g a l India 3 0 0 f a m i l i e s r e c e i v e d d i s i n f e c t i o n of drinking water and another 300 families did n o t . All o t h e r f a c t o r s w e r e d e t e r m i n e d to b e e s s e n t i a l l y the s a m e . Over a nine month period t h e r e w a s an 807. r e d u c t i o n in the i n c i d e n c e of d i a r r h e a l d i s e a s e a m o n g the c h i l d r e n r e c e i v i n g the d i s i n f e c t e d w a t e r and o n l y a 5'/. r e d u c t i o n in t h e c h i l d r e n which did n o t r e c e i v e d i s i n f e c t e d w a t e r . In s i t u a t i o n s w h e r e w a t e r is the p r e d o m i n a n t v e h i c l e for the t r a n s m i s s i o n of T y p h o i d , P a r a t y p h o i d , C h o l e r a , C a m p y l o b a c t e r , R o t o v i r u s , H e p a t i t u s , D r a c o n t i a s i s or G i a r d i a s i s , a d e q u a t e l e v e l s of d i s i n f e c t a n t and a d e q u a t e c o n t a c t t i m e w i l l r e s u l t in r e d u c e d i n c i d e n c e of d i s e a s e . The h e a l t h b e n e f i t s o f m o r e r e l i a b l e , simpler and lower c o s t d i s i n f e c t i o n are p a t e n t l y o b v i o u s . C A U S E S OF D I S I N F E C T I O N FAILURE To r e s o l v e t h e p r o b l e m of w i d e s p r e a d f a i l u r e o f d i s i n f e c t i o n in L a t i n A m e r i c a and t h e C a r i b b e a n it is f i r s t n e c e s s a r y to i d e n t i f y and u n d e r s t a n d the n a t u r e of the c a u s e s b e h i n d t h e f a i l u r e . S t u d i e s and - 3 - investigations* have disclosed a number for f a i l u r e to d i s i n f e c t w h i c h a r e ; of c o m m o n l y cited reasons 1. U n d e p e n d a b l e or u n a v a i l a b l e s u p p l y of c h e m i c a l s . 2. Unavailable spare parts. 3. O p e r a t i o n a l r e q u i r e m e n t s too c o m p l e x for local o p e r a t o r s to carry o u t . A. R e p a i r of e q u i p m e n t too c o m p l e x for local o p e r a t o r s to m a k e . 5. I n a d e q u a t e i n f r a s t r u c t u r e to s u p p o r t the p u r c h a s e * t r a n s p o r t s and s t o r a g e of c h e m i c a l s , s p a r e p a r t s and s u p p l i e s . 6. User d i s s a t i s f a c t i o n w i t h w i d e l y v a r y i n g c h l o r i n e l e v e l s . 7 . D i f f i c u l t y i n v o l v e d in local s t o r a g e , h a n d l i n g , m i x i n g and d o s i n g of c h e m i c a l s . 8. Insufficient equipment d u r a b i l i t y . 9. I n s u f f i c i e n t o p e r a t o r t r a i n i n g and e x p e r i e n c e as well as inadequate basic education. 10. Inadequate safety c o n s i d e r a t i o n s . 11. F o r e i g n e x c h a n g e r e s t r i c t i o n s . In a l m o s t all s p e c i f i c i n s t a n c e s t h e r e are m u l t i p l e u n d e r l y i n g c a u s e s for the f a i l u r e to d i s i n f e c t ; s o m e of t h e c a u s e s o p e r a t e in s e r i e s and o t h e r s o p e r a t e in p a r a l l e l and they m u s t b e r e s o l v e d a c c o r d i n g l y to o b t a i n a lasting s o l u t i o n . A v a r i e t y of a p p r o a c h e s h a v e b e e n t a k e n in the p a s t to s o l v e t h i s d i l e m m a i n c l u d i n g i n s t i t u t i o n a l and h u m a n r e s o u r c e d e v e l o p m e n t . The results have been less than s a t i s f a c t o r y w i t h an i n c r e a s e of o n l y a f e w p e r c e n t in t h e water s y s t e m s a d e q u a t e l y d i s i n f e c t e d o v e r the last 2 0 y e a r s . A number of a l t e r n a t i v e t e c h n o l o g i e s s u c h as o z o n a t i o n , u l t r a v i o l e t light, halogenated r e s i n s , radiation, iodination, chlorine dioxide, c h l o r a m i n e s , and a p p r o p r i a t e t e c h n o l o g i e s for h y p o c h 1 o r i n a t i o n h a v e b e e n i n t r o d u c e d to o v e r c o m e the p r o b l e m but they h a v e n ' t r e a l l y c i r c u m v e n t e d the m a j o r c a u s e s of t h e p r o b l e m . Some have even added to them. U n f o r t u n a t e l y the g r e a t m a j o r i t y of w o r k and a d v a n c e m e n t s in d i s i n f e c t i o n t e c h n o l o g y h a v e b e e n aimed p r i m a r i l y at s o l v i n g p r o b l e m s e n c o u n t e r e d in the h i g h l y d e v e l o p e d and i n d u s t r i a l i z e d countries. T h e y h a v e n o t b e e n d i r e c t e d t o w a r d s s o l u t i o n of t h e s p e c i f i c p r o b l e m s and c o n s i d e r a b l y d i f f e r e n t p r o b l e m s of d e v e l o p i n g countr i e s . F O R M U L A T I O N OF T H E M 0 G G 0 D CONCEPT: B e c a u s e no s i n g l e c o n v e n t i o n a l m e t h o d of d i s i n f e c t i o n s e e m e d to o v e r c o m e a s u f f i c i e n t n u m b e r of t h e s e c a u s e s , v a r i o u s c o m b i n a t i o n s of them w e r e e x p l o r e d . T h e s i m p l e c o m b i n a t i o n of m e t h o d s u s u a l l y r e s u l t e d in m u c h m o r e c o m p l e x o p e r a t i o n a l p r o b l e m s w h i c h o v e r s h a d o w e d any a d v a n t a g e s g a i n e d . A n o t h e r f a c t o r to be c o n s i d e r e d w h e n s e l e c t i n g a s u i t a b l e d i s i n f e c t a n t is t h e m i c r o b i o l o g i c a l s t a b i l i t y in water d i s t r i b u t i o n systems.X A l a r g e n u m b e r of b a c t e r i o l o g i c a l s t r a i n s as well a s m o l d s and p r o t o z o a a r e c a p a b l e of a f t e r g r o w t h e v e n though the w a t e r m a y h a v e b e e n a p p r o p r i a t e l y t r e a t e d . The p r o b a b i l i t y of t h i s p h e n o m e n a o c c u r r i n g is p a r t i c u l a r l y likely w h e r e the water c o n t a i n s s i g n i f i c a n t q u a n t i t i e s of o r g a n i c c o u m p o u n d s and in a r e a s of w a r m e r w a t e r and g r o u n d t e m p e r a t u r e s . * T h e s e m i c r o o r g a n i s m s n o t o n l y r e s u l t in d e c r e a s e d o r g a n o l e p t i c q u a l i t y b u t may also p o s e a h e a l t h r i s k . S i n c e b o t h the w a r m e r t e m p e r a t u r e s and - A - o r g a n i c levels a r e the p r e d o m i n a t e c o n d i t i o n s in L a t i n A m e r i c a and t h e C a r i b b e a n it is i m p o r t a n t that a d i s i n f e c t a n t m e t h o d o l o g y b e e f f e c t i v e , e f f i c i e n t , broad s p e c t r u m and that it a l s o p r o v i d e an adequate residual. For all of t h e s e r e a s o n s P A H O b e g a n e x p l o r i n g the f e a s i b i l i t y of i n n o v a t i v e t e c h n o l o g y w h i c h might avoid or e l i m i n a t e a s u f f i c i e n t n u m b e r of the a f o r e m e n t i o n e d p r o b l e m s and c a u s e s of f a i l u r e in order to i n c r e a s e t h e p r o b a b i l i t y of a c h i e v i n g s u c c e s s f u l s u s t a i n e d d i s i n f e c t i o n of s m a l l c o m m u n i t y w a t e r s y s t e m s . C r i t e r i a o f d e s i r a b l e c h a r a c t e r i s t i c s for a d i s i n f e c t i o n d e v i c e s u i t a b l e for s m a l l t o w n s and rural a r e a s in L a t i n A m e r i c a w e r e p r e p a r e d by P A H O to u s e in d i s c u s s i o n s w i t h p o t e n t i a l d e v e l o p e r s and researchers. T h i s included A ) , s i m p l i c i t y of o p e r a t i o n and m a i n t e n a n c e a n d if p o s s i b l e a v o i d a n c e of the n e c e s s i t y for c h e m i c a l and m a t h e m a t i c a l c a l c u l a t i o n s ; B ) r o b u s t and d u r a b l e e q u i p m e n t w h i c h is also e a s y to r e p a i r ; C> u s e of l o c a l l y or r e a d i l y a v a i l a b l e p r i m a r y c h e m i c a l s ; D ) r e l i a b l e , e f f e c t i v e and s a f e d i s i n f e c t a n t w h i c h would function over a wide range of typical physica1-chemica1 c o n d i t i o n s and w h i c h leaves an a d e q u a t e r e s i d u a l . This criteria f i r s t led to c o n s i d e r a t i o n of e x i s t i n g d e v i c e s for o n - s i t e g e m e r a t i o n of s o d i u m h y p o c h l o r i t e , but actual e x p e r i e n c e had s h o w n t h e s e d e v i c e s to b e too c o m p l e x for the t a r g e t e d c o m m u n i t i e s . D u r i n g t h e l i t e r a t u r e r e s e a r c h and f o l l o w - u p w i t h a g e n c i e s , i n s t i t u t i o n s , s c i e n t i s t s and d e v e l o p e r s it b e c a m e e v i d e n t that it w a s u s u a l l y s i m p l e r a n d less c o s t l y to g e n e r a t e a m i x t u r e of d i s i n f e c t i n g oxidants than a single pure o x i d a n t . T h e r e are several additional p o t e n t i a l a d v a n t a g e s to the u s e of a m i x t u r e of o x i d a n t s . : 1. D i f f e r e n t o x i d a n t d i s i n f e c t a n t s h a v e s o m e w h a t d i f f e r e n t r a n g e s in w h i c h t h e y e f f e c t i v e l y o p e r a t e . C o m b i n i n g t h e m may i n c r e a s e the p o s s i b i l i t y of b r o a d e n i n g that r a n g e . 2 . C o m b i n a t i o n o f o x i d a n t s c a n act s y n e r g i s t i c a 1 1 y as d i s infectants. 3. D i f f e r e n t o x i d a n t s leave r e s i d u a l s of d i f f e r i n g h a l f - l i v e s 4. D i f f e r e n t o x i d a n t s h a v e g r e a t e r a f f i n i t y for r e a c t i o n w i t h v a r i o u s r e d u c i n g a g e n t s and by c o m b i n i n g them it may be' p o s s i b l e to m i n i m i z e t h e u n d e s i r a b l e s u b p r o d u c t s p r o d u c e d . It w a s t h i s r e a l i z a t i o n w h i c h i n d u c e d P A H O to p u r s u e t h e d e v e l o p m e n t of m i x e d o x i d a n t s g e n e r a t e d o n - s i t e for d i s i n f e c t i o n (MOGGOD). EFFECTIVENESS OF MIXf£D O X I D A N T S : Table A d e p i c t s Y t h e r e l a t i v e o x i d a t i o n p o t e n t i a l of s o m e of t h e strongest known oxidants. The h y d r o x y l r a d i c a l , a t o m i c o x y g e n , o z o n e , h y d r o g e n p e r o x i d e , the p e r h y d r o x y l r a d i c a l , h y p o c h l o r o u s acid and c h l o r i n e a r e a m o n g t W o x i d a n t s p r o d u c e d by M O G G O D d e v i c e s . P e r m a n g a n a t e is n o t . A l t h o u g h h y d r o g e n p e r o x i d e and the p e r h y d r o x y l r a d i c a l a r e n o t e f f e c t i v e d i s i n f e c t a n t s in w a t e r t h e y do s a t i s f y t h e r e d u c i n g a g e n t s in w a t e r w h i c h w o u l d o t h e r w i s e u s e up the m o r e effective disinfecting oxidants. - 5 TABLE A RELATIVE OXIDATION POTENTIAL OF STRONG OXIDANT SPECIES BASED ON REFERENCE OF CHLORINE = 1.OO Oxidant Species FLUORINE HYDROXYL RADICAL ATOMIC OXYGEN OZONE HYDROGEN PEROXIDE PERHYDROXYL RADICAL PERMANGANATE HYPOCHLOROUS ACID CHLORINE Ox idation Po tent i a 1 (volts) 2.87 2.80 2.42 2.07 1 .77 1 .70 1 .68 1 ,<+9 1 .36 Relat ive Ox i dat ion Power * 2.25 2.05 1 .78 1 .52 1 .30 1 .25 1 .23 1 . 10 1 .00 Duguet, Brodard, Dussert and Mallevialle found that the addition of hydrogen peroxide to water during ozonation increased the rate of ozone transfer and the oxidation of organic compounds. They also found that the addition of hydrogen peroxide in the ozonation process resulted in significant reduction of precursors of triha1omethanes. Charles P. Hibler, determined that in water with a turbidity of 0.53 to 0.73 NTU containing 10,000 to 40,000 giardia cysts per gallon,the combination of photozone (0.3 to 0.6 mg/1 ) and chlorine (0.2 to 0.58 mg/1) for a period of 30 minutes of exposure were sufficient to kill or inactivate all of the Giardia cysts while neither photozone nor chlorine alone was able to achieve inactivation. The biochemical mechanisms involved in the inactivation of the cysts is not yet well understood. It has been observed that long duration contact time resulted in destruction of the cyst. Disinfection with MOGGOD appears to be at least as effective and very probably more effective than with straight chlorine. Additional closely controlled laboratory testing will be required to precisely determine this Velation. THE DEVELOPMENT OF M( MOGGOD DEVICES: (ue to tt Largely due the normal.course of scientific and commercial development, and.in a small part due to PAHO'S encouragement and promotion, several advanced fully functional prototypes of devices for on-site generation of mixed oxidant disinfectants (MOGGOD) have been developed and improved. Two distinct groups of devices which produce mixed oxidants for disinfection have evolved; one relies upon - 6 electrolysis and the other upon photolysis to generate the mixed oxidants. Both show considerable promise of overcoming or circumventing many of the major problems and impediments to d i s i nfec t ion. The photolysis process utilizes short wave (>185nm> length ultraviolet light to dissociate oxygen molecules into activated species. A schematic of this process is shown in Figure 1. In the PHOTOZONE process ambient air is passed along such a lamp and the generated plasma is diffused into an aqueous solution which is further irradiated by the ultraviolet light further boosting the oxidizing potential as well <as contributing to the disinfection. The resultant oxidants in the water stream include ozone, hydroxyl radical, hydrogen dioxide, hydrogen p e r o x i d e , and atomic oxygen. This mixture of oxidants has been determined to have a greater oxidizing power than chlorine g a s . It h a s also been shown to be ^n excellent disinfectant. The PHOTOZONE process uses typically about 7 to 11 kilowatt hours of energy to produce one kilo of the PHOTOZONE gas. WATER OUTLET WATER TREATMENT CELL /s^T^y-i----•••,.-...-..-_-..- _ ~ ^ - ^ , ^TJr •—V-«— .-— -y.-^-—-v.-— —>—^ UV LAMP VENTURI L,„„ QUARTZ TUBE • AIR INLET T. ^ AIF[R TREATMENT CELL CHECK VALVE Figure 1. Schematic of the PHOTOZONE principle. Unfortunately PHOTOZONE does not include a durable residual among its mixedx oxidants. Since an effective and durable residual is necessary\in Latin American water systems because they are subject to recontamin\ation this device has not yet been installed in the demonstration project but is mentioned here because it is a generator of mixed oxidants. Electrolysis of a saturated salt solution also is capable of generating mixed oxidants and a large portion of them provide and effective residual disinfectant. The generation of a oxidants through electrolysis has been carrr'ed out on a commercial scale since the turn of the century and steady advancements and improvements have 7 been made particularly in the chlor-alkalai industry. The introduction of the dimensionally stable anode and the perfluorinated membranes in 196.9 and their steady improvement has radically improved the efficiency? lowered the cost of production} and greatly reduced power requirements of the electrolysis p r o c e s s e s . Today 90'/. of the chlorine capacity of North America is produced utilizing these devices and the resultant methodology. These advancements have made the on-site generation of mixed oxidant gas disinfectants a feasible alternative. The same basic technology, but adapted to insure operational simplicity, durability and compatiblity with conditions in remote, small and poor communities has been used to develop the MOGGOD units. To do this some of the efficiency of the electrolysis process has been sacrificed but it is more than compensated for by a gain of overall efficiency which takes into consideration the community capability, storage, transportation, national supporting infrastructure, local conditions and the prevalent human element. A number of prototypes have been produced by different entities and they are considerably beyond the laboratory bench model stage with several units being produced commercially and one particular model having functioned quite well in 10 different actual field installations. The first installation has now been in operation for over 3 years and continues to function exceptionally well, equalling or exceeding the efficiency of conventional methods of chlorination which had previously been used but failed to perform satisfactorily. CHLORINE AND OXYGEN SPECIES t WATER AND SALT J HYDROGEN t 2 - 10 VL DC » t ANODE CELL UJ irt tu Q O < ii £ tu I CATHODE CELL i SODIUM <; HYDROXIDE < • Figure a. Schematic of MOGGOD e l e c t r o l y t i c c e l l . -a - i Figure 2 is a schematic drawing of the MOGGOD unit indicating the relation of the electrolytic cell component* and the input and output of chemicals. The cell is divided into the anode and cathode compartments by a semipermeable membrane ( Nafion ) which is a high performance reinforced composite of perfluorinated cation exchange copolymer. The unit also incorporates a TIR-2000 DSA anode (ELTECH) and a cathode of <^0 stainless steel. In addition auxilliary electrodes which are operated at a lower EMF than the primary anode are located between the anode and the m e m b r a n e . A saturated solution of sodium chloride is maintained in the anode compartment by the addition of water and excess sodium chloride and a 107. solution of sodium hydroxide is maintained in the cathode compartment by the addition of sufficient water and drawoff of excess liquid. Chlorine and activated oxygen species (the mixed oxidant gases) are generated at the anodes while hydrogen gas and sodium hydroxide are formed at the cathode. In the MOGGOD process the mixed oxidant gases are injected into the water to be disinfected, the hydrogen gas is vented to the atmosphere and the excess sodium hydroxide is collected to be utilized for other purposes or to be disposed of. A somewhat similar cell was described by Michalek and Leitz <*> in 1972, but no mention was made of oxygen species being generated at the anode. This could have been due to both the absence of an auxilliary electrode and the use of a DSA anode developed specifically for the generation of chlori ne rather than one for the generation of oxygen. Figure 3 is a graph which portrays the useful life of the TIR 2000 anode as a function of current density in amperes per square inch of anode surface in a solution of about 15V. sulfuric acid. Increased thickness of the iridium oxide based coating yields an iKaa-r Heavy 150 gpl H2S04 • 50 d e g . , C Extended 1033 Lifetime (days) ira- te a.i Figure 3. -<—I I t M l -«—•—<-M-t+- i is Current D e n s i t y ( I n as I) TIR-2000 Lifetime vs. Current -4 1- I I I I H lea Density - 9 - increased u s e f u l life e x p e c t a n c y for the a n o a e . S i n c e the o p e r a t i o n a l c u r r e n t d e n s i t y of t h e M O G G O D u n i t r a n g e s b e t w e e n around 0.6 and 1.0 a m p s p e r ' s q u a r e inch the life of the a n o d e will range b e t w e e n about 3 and 8 y e a r s for the e x t e n d e d life c o a t i n g and from 7 to 12 y e a r s for t h e h e a v y c o a t i n g if the e l e c t r o d e s are in o p e r a t i o n c?^ h o u r s a d a y . Another m e t h o d w h i c h is being d e v e l o p e d for the g e n e r a t i o n of a s o l u t i o n of mixe-d o x i d a n t d i s i n f e c t a n t s u s e s an iridium coated t i t a n i u m cell w i t h laminar f l o w . T h i s d e v i c e w h i c h h a s functioned well in the l a b o r a t o r y h a s yet to b e f i e l d t e s t e d in L a t i n A m e r i c a . The d i s i n f e c t a n t s o l u t i o n h a s b e e n t e s t e d for e f f e c t i v e n e s s and e q u a l s of e x c e e d s t h a t of c h l o r i n e . PAHO'S PROJECT FOR DEVELOPMENT OF M 0 G G 0 D TECHNOLOGY: The initial p h a s e the M O G G O D d e v e l o p m e n t p r o j e c t w a s d e v o t e d to p r o m o t i o n , e n c o u r a g e m e n t and f o s t e r i n g the M O G G O D c o n c e p t and w a s p l a n n e d to o b t a i n c o n t r i b u t i o n s f r o m g o v e r n m e n t a g e n c i e s , u n i v e r s i t i e s and a c a d e m i c i n s t i t u t i o n s , p r o f e s s i o n a l o r g a n i z a t i o n s and p r i v a t e i n d u s t r y . T h i s w a s c a r r i e d out p r i m a r i l y through p e r s o n a l c o n t a c t and d i s s e m i n a t i o n and s h a r i n g of i n f o r m a t i o n . It w a s also i n c o r p o r a t e d into P A H O ' s p r o g r a m for i m p r o v e m e n t of d r i n k i n g water q u a l i t y and the M O G G O D c o n c e p t w a s b r o u g h t f o r t h at P A H O w o r k s h o p s , c o n f e r e n c e s , s e m i n a r s and m e e t i n g s w h i c h in any way w e r e r e l a t e d to d r i n k i n g w a t e r , water q u a l i t y , w a t e r t r e a t m e n t , distribution systems. A d v a n c m e n t s in all r e l a t e d a r e a s of t e c h n o l o g y were closely monitored. S i t e s w h e r e i n s t a l l a t i o n of M O G G O D type d e v i c e s had b e e n m a d e by the p r i v a t e s e c t o r w e r e v i s i t e d . S o m e of the m o r e p r o m i s i n g p r o t o t y p e s and s e c o n d g e n e r a t i o n M O G G O D d e v i c e s w e r e p u r c h a s e d and limited t e s t i n g w a s c a r r i e d o u t by P A H O s t a f f . Many p r o j e c t p r o p o s a l s for M O G G O D d e v e l o p m e n t w e r e p r e p a r e d and s u b m i t t e d to f u n d i n g a g e n c i e s . A total of four M O G G O D d e v i c e s w e r e p u r c h a s e d by P A H O for u s e in s i t u a t i o n s of e m e r g e n c i e s b r o u g h t a b o u t by n a t u r a l d i s a s t e r s for t e m p o r a r y d i s i n f e c t i o n of water s u p p l i e s . This was done because s h i p m e n t of c h l o r i n e p r o d u c t s by a i r f r e i g h t w a s p r o h i b i t e d and the p a r t i c u l a r d e v i c e s u t i l i z e d salt a s t h e p r i m a r y m a t e r i a l . They f u n c t i o n e d well b u t t h e length o f o p e r a t i o n w a s too s h o r t to d r a w many c o n c l u s i o n s a b o u t d u r a b i l i t y , c o n t i n u i t y o f ' o p e r a t i o n , r e p a i r s or m a i n t e n a n c e p r o b l e m s . In July 1986 P A H O a w a r d e d a r e s e a r c h g r a n t for i n v e s t i g a t i n g t h e e f f e c t i v e n e s s and e f f i c i e n c y of a M O G G O D d e v i c e r e l a t i v e to c h l o r i n e and in D e c e m b e r 1986 a d v a n c e f u n d s w e r e r e c e i v e d from U N D P under t h e PAHO/UNDP Critical Poverty Program. Matching funds were obtained f r o m c o u n t r y o f f i c e s and m o r e t h a n f o r t y M 0 G G O D d e v i c e s h a v e b e e n p u r c h a s e d and s e n t to L a t i n A m e r i c a and t h e C a r i b b e a n for d e m o n s t r a t i o n p r o j e c t s , field t e s t i n g , l a b o r a t o r y a n a l y s i s . Countries which have received these d e v i c e s are Argentina, Bolivia, Brasil, Columbia, Costa Rica, E c u a d o r , Guatemala, Honduras, Jamaica, Mexico, Peru and S t . L u c i a . M o s t o f t h e c o u n t r i e s h a v e a g r e e d to c o l l a b o r a t e in the d e m o n s t r a t i o n / d e v e l o p m e n t p r o j e c t and h a v e 10 commenced various activities but two of the countries have declined. Collaboration is under consideration in Cuba, Barbados? Chile, Paraguay and Venezuela. Research has been carried out in Argentina, Mexico, and the USA and more is in the formative stages in Argentina, Brasil, Colombia, Cuba, Guatemala, Ecuador and Peru. PURPOSE OF THE DEVELOPMENT PROJECT: The overall objective of the development project is to foster and accelerate the development of MOGGOD technology in a manner which will serve the needs of small towns, communities and rural villages of Latin America and the Caribbean. The specific objectives are to: 1. Test various MOGGOD devices under as wide a range of actual but typical field conditions as possible to determine advantages and disadvantages, strengths and weaknesses and to make recommendations for improvement of the devices. 2. Obtain a better understanding of the technologies involved the production and utilization of mixed oxidants in 3. Disseminate knowledge and information regarding MOGGOD among the institutions and agencies of Latin America. *•. Encourage international this technology. collaboration in the development of 5. Provide data on which to base installation criteria, operation and maintenance instructions, to obtain further refinements and improvements in design and manufacturing. 6. Determine the feasibility of manufacturing locally. the equipment 7. Develop parametric relationships for equivalent mixed oxidant residual and free chlorine residual. 8. Determine the minimum mixed oxidant residual pathogen free water. to guarantee 9. Feed back field performance characteristics to manufacturers to facilitate improvement of equipment performance and reliability and to improve manufacturer support services and reduce c o s t s . 10. Determine and understand MOGGOD. 11. Develop a data base for maintenance costs. the complex chemical reactions of installation and operation and 12. Define commercial quality standards for manufacturing MOGGOD - devices and improve technical 13. Determine the practical capac i ty . 1*1 - specifications. upper limits of MOGGOD device 14. Determine the effectiveness of MOGGOD against specific waterborne pathogens under varying conditions of turbidity* pH, and temperature. 15. Investigate the potential of MOGGOD for removal of undesirable substances from drinking water such as iron, heavy metals, phenols, cyanides etc. SUMMARY OF ACTIVITIES CARRIED OUT TO DATE: 1. Lecture-demonstrations of MOGGOD Technology were carried out in twelve countries> involving 48 agencies or institutions. 2. A total of 47 units of MOGGOD and assesories were purchased Argentina, Bolivia, Brasil, Colombia, Ecuador, Guatemala, Honduras, Jamaica, Mexico, Panama, Peru and St. Lucia. 3. Models for easy to understand manuals for: a) installation of MOGGOD, and b) operation and maintenance of MOGGOD were prepar under contract in both Spanish and English. 4. Technical information on MOGGOD was provided to all of the pertinent agencies of the countries participating in the PAHO/UNDP Program and to ar\ additional seven countries and thei appropriate agencies. 5. Draft proposals for national MOGGOD demonstration projects were prepared and provided to Argentina, Colombia, Mexico, and Peru for submittal to the national offices of UNDP for funding. 6. Draft terms of reference for participation in a regiona,l MOGGOD demonstration project were developed and provided to eight countr ies. 7- Three MOGGOD research projects were implemented and five additional research proposals and protocols and are in the stag of soliciting funds. 8. As a direct result of this project, manufacturing of MOGGOD devices has been initiated by private industry (FENAR) in Argentina and is being explored in Mexico by CEDAT. CEDAT has developed a number of prototypes, which are being field tested. It is under consideration in Colombia 9. MOGGOD devices have been installed in seven of the participant countries and field testing is underway . to 10. Field visits were made to a total of 20 potential field demonstration sites and instructions for site preparation and MOGGOD installations were provided. 11. An i n t e r n a t i o n a l s e m i n a r on d i s i n f e c t i o n of small c o m m u n i t y s u p p l i e s w i t h M O G G O D w a s held almost e x a c t l y o n e year after demonstration - development project was initiated.. water the FINDINGS TO D A T E : T h e r e are s e v e r a l p o t e n t i a l e c o n o m i c b e n e f i t s of improved disinfection through MOGGOD. T h e r e is b o t h the d i r e c t cost r e d u c t i o n of the d i s i n f e c t a n t i t s e l f and that w h i c h is d u e to s i m p l i f i e d o p e r a t i o n and m a i n t e n a n c e r e q u i r e m e n t s of the a p p a r a t u s . Another e c o n o m i c b e n e f i t w o u l d a f f e c t t h o s e c o u n t r i e s w h i c h import c h l o r i n e and c h l o r i n e p r o d u c t s by r e d u c t i o n in f o r e i g n e x c h a n g e of c u r r e n c y . F i n a l l y , t h e r e is t h e i n t u i t i v e l y o b v i o u s b u t less d e f i n i t i v e economic benefit of a healthier people. A l t h o u g h m o r e t i m e is needed to s u f f i c i e n t l y s t r e s s the c o m p o n e n t s of t h e M O G G O D d e v i c e s it p r e s e n t l y a p p e a r s that the of M O G G O D d i s i n f e c t a n t r a n g e s f r o m U S * 0.E5 to 0.60 per kilo produced. cost T h e r e a r e a n u m b e r of a d v a n t a g e s of M O G G O D w h i c h should h e l p avoid a number o f t h e p r o b l e m s e n c o u n t e r e d in s u s t a i n i n g c o n v e n t i o n a l ch1 o r i n a t i o n , p a r t i c u l a r l y in small and r e m o t e t o w n s and c o m m u n i t i e s . They a r e : The o n l y m a k e up c h e m i c a l s ^re salt ( s o d i u m c h l o r i d e ) and w a t e r . S o d i u m c h l o r i d e is a v a i l a b l e a l m o s t e v e r y w h e r e for other u s e s . T h i s c h e m i c a l is e a s i l y t r a n s p o r t e d , s t o r e d , h a n d l e d w i t h m i n i m a l hazard to t h e e n v i r o n m e n t and n o n e to the w o r k e r . It is a l s o o n e of the least e x p e n s i v e c h e m i c a l s a v a i l a b l e . Power r e q u i r e m e n t s Bre e x t r e m e l y low. T h e v o l t a g e r e q u i r e m e n t is b e t w e e n 5 and 10 v o l t s at the e l e c t r o d e s and t h e c u r r e n t d r a w n is about 12 a m p s per k i l o g r a m of d i s i n f e c t a n t g e n e r a t e d over a 2 ^ hour p e r i o d . If c o n v e n t i o n a l e l e c t r i c i t y is n o t a v a i l a b l e it is f e a s i b l e to u t i l i z e p h o t o v o 1 t a i c s or m i n i - g e n e r a t o r s a n the w a t e r t r a n s m i s s i o n line for a power s o u r c e . Operational r e q u i r e m e n t s are visually o r i e n t e d . M a t h e m a t i c a l and c h e m i c a l s k i l l s a r e n o t e s s e n t i a l for the c o r r e c t o p e r a t i o n . It c a n b e v i s u a l l y d e t e r m i n e d w h e n it is n e c e s s a r y to add s o d i u m chloride. T h e o p e r a t o r m e r e l y l o o k s to s e e if the salt c r y s t a l s or the w a t e r level a r e g e t t i n g low and a d d s s o m e m o r e if necessary. T h e a m o u n t of d i s i n f e c t a n t a p p l i e d is d e t e r m i n e d by the a d j u s t m e n t of a dial ( r h e o s t a t ) to o b t a i n a p r e d e t e r m i n e d c u r r e n t i n d i c a t e d by a n e e d l e . All of t h i s s i m p l i f i e s o p e r a t i o n for the t y p i c a l p o o r l y e d u c a t e d o p e r a t o r . The o x y g e n s p e c i e s of the m i x e d g a s d i s i n f e c t a n t are the d o m i n a n t s p e c i e s a n d tend to r e a c t w i t h o r g a n i c s and o t h e r s u b s t a n c e s b e f o r e t h e c h l o r i n e s p e c i e s . T h i s r e s u l t s in the chlorine species acting primarily as a r e s i d u a l . This generally r e s u l t s in i m p r o v e d t a s t e and o d o r of the w a t e r and e n h a n c e s user t I - 13 - support for continuous and re-liable disinfection. The electrode to electrode power consumption in the MOGGOD units to date fall in the range of ^ kilowatt hours per kilog>~am °f oxidant produced. The MOGGOD device produces only the amount of oxidant needed instantaneously thereby decreasing the problems of storing large quantities of highly reactive substances. To date it has been determined that MOGGQD disinfection is at least equivalent to disinfection with chlorine in both the laboratory and actual field installations. Additional experiments are necessary to check the effectiveness against various pathogens. The weakest component of the MOGGOD devices is the membranes. Care must be taken to not puncture them. Even though training has been given and warnings of the fragility of the membrane, it has been punctured when the operator tries to clean off deposits with something other than water, such as a brush or screwdriver. Some of the techniques and methods used for installing and replacing membranes do not lend themselves well to easy repairs. The use of impure salt (sodium chloride) has caused more problems than any other factor through clogging of the membrane. Apparently there is a great temptation to use impure salt and the unit will function for quite some time using impure salt but the decrease in useful membrane life is directly proportional to the increase in impurities. It is possible to clean the membrane with an acid solution but the inconvenience and labor costs ^re higher than the difference in cost between pure and unpure salt. Even though instructions have been given and installation drawing provided a number of installation have been poorly designed and constructed. A technical expert should be present for the first installations in a country or region of a country. A concerted collaborative effort should be made to develop a good selection of standard drawings for typical installation conditions in Latin America and the Caribbean. MOGGOD devices do not constitute a panacea but a good for disinfection in small community systems. alternative Even though the operation and maintenance of the MOGGOD devices are extremely simple, training is nonetheless required for new users \ of this technology. They require attention at least once a week and preferably twice a week. EXTENDED ABSTRACT COMPARATIVE BACTERICIDAL AND VIRICIDAL ACTIVITY OF GENERATED OXIDANTS USED FOR THE DISINFECTION OF WATER ON-SITE PAN AMERICAN HEALTH ORGANIZATION WORKSHOF LIMA, PERU DECEMBER 7-11. 1987 VINOEN'J P OLIVIER I DEPARTMENT OF GEOGRAPHY AND ENVIRONMENTAL ENGINEERING THE JOHNS HOPKINS UNIVERSITY BALTIMORE, MARYLAND A small pilot scale study was conducted in the laboiatory to determine the efficacy of the mixed oxidants <?e:.i_ 1 a':eo froi.v ."r::-..;3 1 electrolytic cell. The specific objectives were: 1. to compare the bactericidal and viricidal activity of the mixed oxidants generated by the on-site generated disinfectant device to that of an equivalent concentration of free chlorine. 2. to determine the presence or absence of short-lived biocidal species in the mixed oxidants produced by the on-site generated disinfectant device. EXPERIMENTAL PROTOCOL Comparative Disinfection , The disinfection trials were conducted in three plug flow reactors, run in parallel. Baltimore City tap water was dechlorinated by filtering through granular activated carbon column and was used for this series of experiments. The dechlorinated tap water was not tempered or buffered. The temperature over the course of the experiments was 18-23 C and the pH ranged from 7.0 to 9.0. A microbial test mixture containing washed and purified suspensions of E. coli, P. aeruginosa, and or B_. subtil is. and F2 virus at level of 10 7 to 10L' of each of the test raicroorganissvts/ml was aspirated into dechlorinated, unteiapered and unbuffered Baltimore city tap water and allowed to mix through a short coil of 1/2 inch tubing prior to the addition of disinfectant. The total flow for the three parallel reactor system was slightly taove than 2 gal/min. The mi -•?-o! i al mixture was metered in such that the microbial tost ;i:. ::t. •„:*.;•• was diluted about 1000 fold. The final microbial density at timir sero was about 10000/ml for each microorganism. Control samples were collected for determination of chlorine residual and microbial density after the granular activated carbon over the course of the experimental trial. The flow containing the test microbial mixture was split in three continuous plug flow reactors. The reactor conditions are listed in table 1. Reactor A, B, and C contained the following disinfectants, the gas form the on-site oxidant generator, the solution prepared from the gas from the oxidant generator and a chlorine solution prepared from chlorine gas, respectively. The presence of short-lived oxidants produced was evaluated by preparing a solution from the oxidant gas about 1 hour prior to the beginning of th«: disinfection trial and allowing the gas to prereaot to dissipateany short-lived intermediates. Table reactors. REACTOR A B C Reactor FLOW GAL/MIN 1'. 0 0. b 0.5 0 ' 0.5 _ conditions for . DISINFECTANT the three parallel plug flow INITIAL MICROBIAL DENSITY tt/ML pri TEMP C oxi gas 10000 7.0-9.0 oxi solution 10000 6.8-9.0 10000 6.8-9.0 . .chlorine 18-2c C 18-23 0 18-23 0 Reactors A, B and C received the same test water at the same microbial, chemical and physical conditions. The oxidant gas or solution was aspirated into each reactor and the oxidant flow war: monitored by a rotameter and controlled with a metering valve. The disinfectant flow was adjusted such that the total residua! oxidant was the same at the first sample port immediately following the disinfectant aspirator and mixing loop. The test system was allowed to equilibrate and was monitored residual disinfectant for 1 sample course prior to beginning each experimental trial. Sampling protocol Each reactor had provisions for 4 sampling ports after thu addition of disinfectant. The contact time for each port and each reactor was determined with fluorescein dye tracer added at the disinfectant aspirator under the conditions of flow used for the experimental trials. The contact times for the sample ports in each reactor are given in table 2. 3 Table 2. Contact time determined by fluorescein dye tracer studies. Fluorescein was added at the disinfectant aspirator and continuously monitored at each sample port. The flow rates for reactors A, B, and C were 1.0, 0.5 and 0.5, gal/rain, respectively. Each number represents the average of AT LEAST 6 trials for each port. TIME. SECONDS A b 7 • 21 21 17 PORT 2 40 77 76 P'-"'RT '•'- 58 115 123 POkT -S 80 150 148 PSACTOR PORT 1 • After equilibration and monitoring, the three plug flow reactors were run simultaneously with three sample cycles for each trial. Samples collected for chemical and biological analysis. Each sample cycle consisted of an initial 200 ml sample to rinse th>-. port and collection beaker, a 200 ml sample for chemical analysis and an approximate 75 ml sample for microbiological analysis. Th-? chemical samples from the first and third cycles were immediately assayed for free oxidant and total oxidant by aruperometric titration while the second cycle chemical sample was used for the determination of pH. The grab biological samples were collected and combined in a 250 ml sterile polyethylenebottle containing 0.2 ml of a 1 % thiosulfate solution to stop the action of the oxidants. Chemical and biological samples were also collected after the carbon filter and before disinfectant addition (This was the zero time sample. No.) for each cycle. Tota] oxidant in the latter samples was determined by the DP.v method and was always negative after the carbon column. The biological assays were conducted as soon as possible after each trial. METHODS Chemical Preparation and Assay of Disinfectants " Chlorine --"'•--..--.-> v. rH amp* -f described in Standard Methods for the Analysis nl -Hater and Haste water. (APHA, 1 9 8 5 ) . The oxidant gas was generated in an electrolytic cell supplied and manufactured by Oxidizers Inc. located in Virginia Beach, Va. , USA. The oxidant g a s generator was set up and operated according to the instructions supplied by the manufacturer with minor modifications Total oxidant will be measured by the amperometrie and colorimetric tuethoth? used for chlorine given in St.aiidard^JleiuJids (A.PHA 1985' MICROBIOLOGICAL {''reparation and Assay of Bacteria Esj2he_r_Lc!iia cc-UL strain B war; grown overnight under aerated conditions at 37 C on tryptone yeast extract (TYE> broth. The bacteria was washed three times in phosphate buffered saline and added to the water to be disinfected at a density of 10,000 colony forming units/ml (cfu/ml). Survival of E.. c.qLi was determined by spread plates on Maoonkey's agar. Red colonies '/•ore counted after incubation at ?1 0 for •!<: hours. ?.0'o_uji.'iIL,iLUai a.t_;:U£l;JiL'£a was «'rown overnight undor aer^t'-d •" •"nd.it ions at 37 C on tryptone yeast extract -'TYE; brorh. The bacteria was washed three times in phosphate buffered sa'iit.e ytid added to the water t o be disinfected at a density of 10.000 cfu/ml. Survival of £. aeja;£j_nj2aa was determined by spread plates on Maconkey's agar. Colorless colonies were counted after incubation at 37 C for 48 hours. Bacillus subtil is spores were prepared were added to the water to be disinfected at a level of about 10000 cfu/ml. Survival of B_, silbtJJJjl spores was determined by spread plates on tryptioase soy agar after treatment of samples at 80 C for 10 .',ni mites. Orange colonies were- enumerated after 48-72 hcurs : •• .'•!•.• .!" -:t- on at room temperature. : ':••:i'ar:--.ion ;3nd Assay at V2 Bacterial Virus The bacterial virus was grown and purified and adde'd to the test system at about 10000 plaque forming units /ml, pfu/ml. The survival of F2 will be determined by the agar overlay technique on tryptone, yeast extract agar using E.. coli K13 as host. Plaques were counted after 18-24 hours incubation at 35 C. RESULTS \ The total oxidant residual reported as available chlorine is shown in figure 1 for the three parallel plug flow reactors for oxi gas, oxl solution and chlorine for the time course of the d i rinf ectio_n\ The d a t a is for experiments conducted at a setting of 5 0 -8.2 amps for the oxi generator and represents the average •f o-.e. trials. The total residual oxidant was similar for the • > .••'•••'•• d i r, i n f e e t a n t s . •ri £•"•"•:••• ;';' si.riv:? the S ' U ^'i v;.• i of J\. !.•••) i + :,i"''i;; 1: '!;• 1 f :' t .<•• /: * ' m wi'nout any oxidant. The level:.; of E. coil -..re nrporre,! <-is the survival fraction, N/No and remained constant over the time course of the experimental trials. Little difference was £ o h i i en CI UJ < o LU Ql < o ^X.' 2 AMPS 00 4 O Vl CO 1 o <X3 r^ r <r 33f -+ L Si U4. Ul h X •31 ^ O o 1 r» i - > l/IC/W l 1 <U U-) '.~j '~'--J o 'INVGIVQ •*: CM o on -r. n r, ! !! N: h i I •J} X :/> • O J ' 1I _ i i i4'! D?- I !':- ^ .•-"••- U1 Lit if] Gfi. I.J ^' -J L . * i ; •, i i_ in. I L> w> -•-J" i_ ro ! _ cu Hi D -+ U1 •V-i. IT). ^N/'N 30-1 "NCiiCiVci T^MAaflS 7 '..J _J o .31 l.T o o < 0 U"i ~) I /"') 00 C/i O O < a LJ Ul cO uT — o O d O CO 2 1 — o ! I O o o .^" u^ o ©^ C_i if) in \ rvi in K) O I if: -4- to I I < 0 O N / N 'NOiiovdJ "ivMAyns 001 n 2 o o o I ) CM Vi Ul *—' T *73 0- O _J X o o o 00 o (/) a o a UJ r'm ai UJ o CD 2 o o o o o T 1 - m o I ITJ *— 1 CM l 1 \ 1 1 in ' — 1v-» 1 rn 1 1 •' *> CN 1 . 1 1i O _ 9 N / N 'NOLLOVdJ "lVAIAdnS OO"! n o o o o 00 o CD o CM < < i >M/N 'NQLLOVSJ i V A l A a n S DO"! n H> observed for the three different reactors. Similar results were obtained for P_. aeruginosa,, fi^ .subtil is and f2 virus. The comparative disinfection of E. ccJLi, P_. aeruginosa, and f2 virus is shown in figures 3a, 3b, and 3c, respectively. The survival of each microorganism is reported as the log of the survival fraction over the time course of disinfection Each of the test microorganisms was rapidly inactivated with each of the test disinfectants. Little difference was observed for the microbial survival for the oxi gn-.;, the oxi solution or the chlorine solution. Figure 4 shows the .tot*] oxi-iant residual for com pa rat i v.; trials where the current to the oxi gas generator was varied fro;.: 2-8 amps. The total oxidant wes about 0.5 mg/1 for the 2 and thA amp trial, while the total oxidant was about 2.5 for the 6 and 8 amp trials. The oxidant residual was constant over the time course of disinfection. The comparative microbial inactivation is shown in figure 5a thru 5c. When the difference in oxidant residual is taken into account, little difference in the disinfectant efficacy for the oxi gas wa.'- found. SUMMARY The gas produced by the on-site disinfectant generator rapidly inactivates £. coli, ' E. aeruginosa, and f2 virus in water. The disinfectant activity the gas appears to be equivalent chlorine solutions at an equal total oxidant residual under the same chemical and physical conditions. No evidence for the presence of biocidal short-lived products was observed. ACKNOWLEDGEMENT This study was supported by the Pan American Hc-.-ilth Organization. The on-sit oxidant generator was supplied by Oxidizers Inc. located in Virginia Beach, Va., USA. The author gratefully acknowledges the assistance of Maria Yolanda Ramirez and Silvio Arango-Jaramillo and the technical assistance of Ed Rhode, Paula Larson, Lynne Cox and Glorestine Toles. // c; < o I o in o o o UJ in on < " I / I O A V 6LU 'J.NVQIXO ivioi / * I q co CO fV > (/> CD • * - cl o *) LU y O o 4 £ Ul O N / N 'NO UOVHJ i V A J A ^ n S O O l 13 i o a'j < i ^3 £C ON/N 'Noaovaj ivAiAans ocn ti i •7J T C! .-i \ ; / \ or'A ex p o o a!' I (/'J Q. < q ! i/ I in 01 •=*- III o a z> 00 CM a tn E D 4 m 4- >£ i in CM I Ml CN I j •M"M.LDVdJ i V A l A d H S 001 *A 7^Ai-,m^Tnni,„;^iA •,-.« i COS A l a m o s T e c h n i c a l A s s o c i a t e s , inc. Presented 'at the International Seminar on Disinfection with Mixed Oxidants Generated Health' Organization, 0nsite) Pan American Lima, Peru, December 5-12, 1987 WATER DISINFECTION WITH A MIXED-OXIDANT SOLUTION Ann M. Pendergrass, Helen F. Gram, Deborah K. Steele, and Marke W. Talley Los Alamos Technical Associates, Inc. Los Alamos, NM Abstract An innovative water t r e a t m e n t system produces a solution of mixed oxidants, including free chlorine, hydrogen peroxide, hypochlorite, ozone, and free radicals from dilute brine. The small, rugged, portable unit operates unattended and at a low power requirement. Each volume of the mixedoxidant solution, which is fed directly into water to be disinfected, can t r e a t up to 1,000 volumes of contaminated water. The t r e a t m e n t method has proved effective against several human pathogens, including cysts and spores. Treated water meets all U.S. drinking water standards and recommendations. 1. Introduction Safe drinking water is a goal but not a reality in many parts of the w o r l d - developed as well as developing countries. One answer to this need is a small, portable water t r e a t m e n t unit that can be safely operated a t low cost by people who are not highly technically trained and that can serve a range of community sizes. Los Alamos Technical Associates, Inc. (LATA), located in New Mexico, has developed a simple, low-voltage electrolytic method of sterilizing potable water that can be used in r e m o t e locations, developing countries, and natural disaster areas. The method requires only electrical power and salt or seawater and produces a mixture of oxidants directly in solution. One volume of the oxidant stream mixed with 50*0 to 1,000 volumes of contaminated water will quickly kill common microorganisms, including human pathogens such as Giardia, Legionella, and Pseudomonas t h a t are resistant to chlorine. The t r e a t e d water meets U.S. drinking water standards and is safe for human consumption. Power requirements are 12 V dc t o 24 V dc, 14 A for a unit capable of producing up to 30,000 £ (8,000 gal) of potable water per hour of operation or 700,000 I (180,000 gal) of potable water in a 24-hr day. The unit operates unattended and can be ^maintained by serni-skilled persons. In addition, no hazardous products are required or produced. The water t r e a t m e n t system developed by LATA is small in size, rugged, and portable. The pilot unit shown is about the size of a television set. The only moving part -4 .OS-Alamos Technical Associates, Inc. of the system is a small pump that moves salt solution through the system. The mixedoxidant solution, which is electrolytically produced, contains free chlorine, hydrogen peroxide, hypochlorite, free radicals, and ozone. This solution mixes directly and easily with the water to be disinfected, offering some advantages over gas-phase systems, which will be discussed later. A U.S. patent application is pending. 2. General Description of the Electrolytic Water Treatment System The water treatment system is designed to be very flexible and simple in both construction and operation. Required parts are a salt solution supply, such as 550 J, (150 gal) tanks; a power source, which can be 220 V ac or 110 V ac; a transformer to produce 12 V dc to 24 V dc, 14 A current; an electrolytic cell to produce the oxidant solution, 10 cm (4 in. x 6 in.); two rotometers to adjust the flow rates of the oxidant and discarded streams; a vacuum breaker seal pot to keep the flow rate of the oxidant solution constant when the supply line is connected to a jet cductor; an oxidant outflow line; and a discard outflow line. The unit is contained in an all-weather fiberglass case. Because salt water is corrosive, all wetted parts are stainless steel or polyvinyl chloride. A diagram of the water treatment system shows its schematic design (Figure 1). External connections supply electrical power and dilute salt solution to the unit. Both power and salt can be supplied in several ways, making the unit highly adaptable,to local conditions. The power supply can be 220 V ac or 110 V ac. According to a study made by one of LATA's engineers, power could also be supplied from solar panels. With some modifications, a 12 V diesel generator could also be used. The dilute salt solution can be provided by seawater or by crystalline NaCl added to water\drawn from the supply line before treatment, as shown in the schematic. Preparation of the dilute salt solution can be simplified for nontechnically trained personnel (Figure 2). A saturated solution of salt is prepared; then a known volume of the saturated solution is diluted to a predetermined volume in the feed tank. 2 The Los Alamos Technical Associates, Inc. js Alamos Technical Associates, Inc. Ui < < N 8 8\ c £ X z < O UJ UI u- Z O UJF F 3 o^ c^ »^ —i < Wl O CO •o o CO u p *-• ca CO CO E o 0) «-. co d OJ l» A Hi Z o c o o CO CO CJ *-» 3 Z OC < > < 5 V a, z Los Alamos Technical Associates, Inc. - saturated concentration of NaCl is not very sensitive to temperature; there is only about a 10% increase (35.7 g to 39.1g/100 ml) between 0°C and 100°C. This variation in salinity can be compensated for by a transformer that supplies a constant current. From the supply tank, salt solution is pumped through the electrolytic cell. Oxidants produced in the cell emerge in the anolyte stream, and the catholyte stream is discarded. The rotometers control the rate of flow through the system. A jet eductor, which has no moving parts, operates on the pressure drop caused by flowing liquid—that is, the oxidant solution is aspirated into the water stream (i.e., venturi effect). The partial vacuum on the feedline of the jet eductor introduces the oxidant solution into the water to be treated. 3. Operating Parameters of the Water Treatment System Sizing Flexibility The water treatment system is designed to be flexible to meet the requirements of the specific location. The oxidant production unit is modular; two or more could be installed in a series if the demand for treated water exceeds the capacity of a single unit uid to provide backup capability if a unit should require maintenance or fail. Alternatively, a unit could be operated for only part of a day. The flow can thus be matched to local demands. Production Capacity One modular unit with the cell operating at 14 A uses dilute brine at the rate of 60 8/hr (16 gal/hr) as feedstock. seawater. The brine is 0.75 M NaCl, which is equivalent to The unit produces 30 8/hr (8 gal/hr) of mixed-oxidant solution and the same volume of discard (Table 1). Based on effectiveness tests, this volume of oxidant solution can treat 30,000 8/hr (8,000 gal/hr) of potable water. Maintenance \ Continuous, unattended operation has been demonstrated with the pilot water treatment system. A unit can be sized so that it is only necessary to replenish the brine 5 )S Alamos Technical Associates, Inc. TABLE 1 WATER TREATMENT SYSTEM OPERATING PARAMETERS Power Use Cell Pump 12 V to 24 V, 14 A 110 V, 1 A Salt Use 1.8 kg/hr (4 Ib/hr) 43 kg/24 hr (95 lb/24 hr) Brine Flow R a t e Oxidant Production Discard Stream 60 Sl/hr (16 gal/hr) 30 8,/hr (8 gal/hr) 30 l/hr (8 gal/hr) Water Treatment Rate at 1: 1000 oxidant solution to contaminated water 30,0(H) d/hr (8,000 gal/hr) 700,000 £/24 hr (180,000 gal/24 hr) supply once each day. Operators need not be highly trained. Their requirements are to fill the brine tanks, turn the unit on, verify flow rates and ampere reading, and test for chlorine in the treated water by using a standard color test kit. Power Sources The pilot water t r e a t m e n t unit was developed for a 220 V, 50 Hz power supply. A constant current transformer supplies 110 V to the pump and variable voltage at 14 A to the cell. The unit can readily be adapted to other power sources. The voltage supplied to the cell to c r e a t e a 14 A current flow may depend on p a r a m e t e r s of the local water used to prepare the brine feedstock. Salt Supply The water t r e a t m e n t system has been developed for dilute brine feedstock such as seawater or 0.75 M (30 g/J or 0.25 lb/gal) of NaCl solution. Alternatively, a s a t u r a t e d - bed feedstock can be diluted to achieve this same concentration. seawater are widely available. \ 6 Both dry NaCl and Los Alamos Technical Associates, Inc. Cost of Operation The economics of operation depend upon local costs for salt and electrical power. The support equipment requirements are modest, including tanks for brine feedstock, assorted piping, a jet eductor to mix the oxidant solution with water to be treated, and a time clock if the unit is to operate on less than a continuous basis. The installation is relatively simple compared with installing a conventional chlorination system. No hazardous materials need to be procured or stored. Potential Applications This small, rugged, simple water treatment unit could be utilized in many locations because it is independent of a developed power grid, of trained maintenance personnel, of hazardous or imported chemical supply, and of adjacent industrial support. Some potential applications include remote permanent locations, mobile exploration teams, natural disaster relief operations, military units, and shipboard installations. A major industrial application is its use in cooling water systems as a replacement for toxic algicides such as chromates. 4. Advantages of a Liquid Mixed-Oxidant System LATA's water treatment system differs from several other systems in that mixed oxidants are produced and used in a dissolved form. This offers several advantages, including the fact that liquids are more readily contained and monitored than gases. Gas leaks constitute a real hazard in commercial installations that use gaseous chlorine or ozone. When gas-phase oxidants are introduced into water, the oxidants must be transferred from gas bubbles into the liquid phase before becoming effective. The velocity of the transfer is proportional to the surface area of the bubbles. In industry, the transfer of materials from gas to liquid is facilitated by creating tiny bubbles and by increasing the turbulence of the liquid phase with a stirrer or static mixer. methods require additional input of energy. 7 These In contrast, a solution of mixed oxidants p&Alamos Technical Associates, Inc. 'mixes rapidly and completely with water to be treated. Here, additional energy is not required for mixing. The oxidant solution Is easy to contain and easy to measure. Any liquid leaks are readily detected and, with this system, can be readily repaired as previously proven during operational testing. The mixed-oxidant solution is introduced into water to be treated immediately after it is produced. This allows even the short-lived oxidants that are electrolytically produced to contribute to the effectiveness of the method in achieving rapid kills of microorganisms. Systems that incorporate some time lag between production and utilization of the oxidants may lose the synergistic effect of any short-lived oxidants. Another advantage to this flow-through system is that the discard stream is not highly caustic, the pH is around 9. The discard stream can be treated as wastewater. Some systems that produce gas-phase oxidants generate a large amount of hydrogen gas along with the chlorine or hypochlorite, leaving a very caustic NaOH residue that cannot be discarded without special precautions. 5. Electrolytic Production of Mixed Oxidants Our studies have shown that mixture of oxidants may be more effective against a mixed population of microorganisms than a single oxidant and thus may offer significant advantages in treating potable water. Different types of microorganisms show the greatest sensitivity to different disinfectants, as shown in Table 2. Although ozone is the overall most effective of the disinfectants shown, chlorine as hypochlorous acid is more effective against viruses (Grayson, 1981). Spores and cysts are difficult to kill by any means. As a bactericidal agent, ozone acts rapidly by lysing the cell wall; whereas, chlorine kills more slowly by diffusing into cells and inactivating the enzyme systems (EPA, 1979). The simultaneous production of several oxidant species, then, could be a real advantage in a water treatment system. \ \ The electrolytic process by which oxidants are generated in LATA's water treatment system depends upon Group VIII metal electrodes (the platinum group) that act as catalytic surfaces to produce free chlorine, hydrogen peroxide, hypochlorite, and strong but short-lived oxidants tentatively identified as ozone and free radicals from NaCl solutions. A typical composition of the mixed-oxidant solution is shown in Table 3. 8 , Los Alamos Technical Associates, Inc. TABLE 2 COMPARISON OF OXIDANT DISINFECTION EFFICIENCY AT 5°C . Disinfectant Virus Spores Amoebic Cysts 03 500 0.5 2 0.5 C l 2 (asHOCl) 20 1.0 0.05 0.05 0.2 <0.02 0.0005 0.005 0.1 0.005 0.002 0.02 Cl 2 (asOCD Cl 2 ( a s H 0 2 C l ) # Oirganism Entril Bacteria 1 •Source: Grayson, M. "Ozone," iin Kirk-Othmer Encyclopedia of CChemical Technology, Volume 16, 3rd ed., John Wiley & Sons, NY, 1981. Under a Small Business Innovative Research (SBIR) grant from the U.S. Navy, investigations were made using electrodes made of platinum, iridium oxide, and ruthenium oxide. Under identical conditions, the iridium oxide electrodes produced the greatest concentrations of chlorine and short-lived oxidants. TABLE 3 COMPONENTS OF MIXED-OXIDANT SOLUTION* Component Concentration (mg/8) Analysis Method Cl 2 385 Phenylarsine t i t r a t i o n H202 200 UV absorbance (290 nm) r HOC1 trace Short-Lived Oxidants (O3, Free Radicals) 30 Phenylarsine t i t r a t i o n Indigo trisulfonate dye decolorization (600 nm) •Conditions: 0.75 M NaCl solution; flow rate, 30 8/hr; IrOo electrodes, 12 V dc, 14 A \ The concentration of oxidant species produced is related to thexcurrent flow across the electrolytic cell, as shown in Figure 3. The data shown were generated using the prototype unit shown earlier, except that a variable power source "was used. 9 )s'Alamos Technical Associates, Inc. PROTOTYPE WATER TREATMENT UNIT ELECTROLYTE 0.7SM NaCl (30 g/f) IN DISTILLED WATER ELECTRODES Ir0 2 PRODUCTION RATE 30 t/hr HYDROGEN PEROXIDE (mg/;) r-«00 FREE CHLORINE (mg//) 700 - i GOO - -300 SHORT-LIVED OXIDANTS (mg/f0 3 ) FREE CI r-50 soo - ?.00 0)0 - - 40 - 30 200 SHORT-LIVED OXIDANTS • - 100 200 - 20 •••* 10 100 ~n 7 (5) i 11 (7.5) i 15 (10) L_ 0 n 18 (12) 22 (13) 25 (14) AMPS (VOLTS) M Figure 3. Influence of Electrical Current on Oxidant Stream Composition 10 HS0C101 <G01| los Alamos Technical Associates, Inc. The catalytic reactions taking place on the electrode surfaces are not completely characterized. Possible reactions, derived from the electrochemistry literature, are shown in Table 4. The generation of short-lived oxidants is supported by dye decolorization studies. Bleaching of indigo trisulfonate dye has been proposed as a test for ozone (Bader and Hoigne, 1981). Although this reaction is not specific for ozone, the reaction rate of the dye with the mixed-oxidant solution suggests that strong oxidant components are produced in addition to chlorine and shows why immediate mixing of the oxidant solution with water to be treated is of the utmost importance (Figure 4). Very rapid dye oxidation occurs within the initial minutes after the mixed-oxidant solution is produced. TABLE 4 POSSIBLE OVERALL ELECTROLYTIC REACTIONS Cell Location Reactions Feed Solution NaCl - Na + + CI" Anode 2 CI" • Cl£ + 2e 40H" * 0 2 + 2H 2 0 + 4e O2 + O* - O3 H 2 0 + O* * H 2 0 2 Cathode 2H 2 0 + 2e • 20H" + H 2 0 2 + 2e - 20* Between the Electrodes This oxidation is produced even faster hypochlorite alone. Cl 2 + 20H" - H 2 0 + OCl~ + CI", than that seen with either chlorine or This empirical evidence supports the possible reactions of the electrolytic cell shown in Table 4. Ozone is known to be very short-lived; the half-life is less than one hour at pH 8 (Glaze, 1987) and is shorter in more alkaline conditions. The shorter the time lag between generating the mixed-oxidant solution and contacting it with contaminated water, the greater the capacity to oxidize the contaminants. LATA's water treatment system is designed to utilize the short-lived oxidants; whereas, 11 Zl ' a u u o m o o ; snQ uoiinjos }uBp;xo puB 'a;uoiqood^H a ^ u o j i n s u j , oSipuj j o a i s y UOIIBZIJOJOO9Q BRQ •* aanSijj IIM* IQiOtta t» 0> OE Niw-3wa oz 01 _ j - ooc ~ \ 00> - 00S UJU0O9 3DNV8aOS8V 003 Noumos 1NVQIXO-Q3XIW 00* 003 0 002 - 00* 00» OOS uiuoOJ 3DNVaaOS3V 003 COi 003 oc> UJU0O3 - 005 33Nvsaosav oco OCX •ouj 'saieioossv |BOiuqoai soiueiv SC Los Alamos Technical Associates, Inc. i systems that provide storage tanks for the oxidants, which are to be mixed with water at some later time, probably lose these components if generated. The mixture of cogenerated oxidants provides a powerful tool for treating potable water. Ozone is known to be particularly effective in killing many types of microorga- nisms. Hydrogen peroxide has been observed to increase the effectiveness of ozone in removing organic substances during water treatment (Glaze, 1987). However, ozone has a short lifetime and provides no long-term protection in treated water. Chlorine provides long-term protection against recontamination, and the presence of chlorine shows that the water has been treated as its concentration is readily measured colorimetrically. 6. Effectiveness of Mixed-Oxidant Solution Against Microorganisms The real test of a water treatment system is its effectiveness against microorganisms, particularly, waterborne human pathogens. The mixed-oxidant solution produced by LATA's water treatment system has been tested against a range of microorganisms, including cysts and spores that are difficult to kill at usual levels of municipal chlorination. To test the effectiveness of the freshly generated oxidant solution, known volumes were added to suspensions of known microorganisms. The treatment ratio, or ratio of oxidant solution to contaminated water, was chosen to initially provide a low level of free chlorine at the lower end of the recommended range, which is 0.2- to 4~rng/«, (USPHS, 1984) to test for effectiveness of the non-chlorine species. With the prototype water treatment unit, the mixed-oxidant solution contained sufficient chlorine; as little as one volume of oxidant solution was mixed with 1,000 volumes of contaminated water. All tests were carried out using standard methods of analysis (Greenberg et al., 1980). A series of six tests were performed. The first three tests were carried out using electrolytic cells which were of different dimension and design and were equipped with platinum electrodes. Also, the mixed oxidants were measured using nonspecific t e s t s first titration with sodium thiosulfate and later by total decolorization of indigo trisulfonate dye. The last three tests were made using the prototype unit shown in Section 1, which was equipped with iridium oxide electrodes. Short-lived oxidants were measured as the difference in the quantity of dye decolorized by a freshly generated solution of mixed oxidants and by the same solution s.ged 24 hr in a filled, tightly closed container. 13 :os Alamos Technical Associates, Inc. A comparison was made of the effectiveness of the mixed-oxidant solution and calcium hypochlorite against Escherichia coli (Table 5). showed a more complete kill after The mixed-oxidant solution 1 min; after 5 min, kill was complete in both treatments. Legionella pneumophila, the agent that causes Legionnaires' Disease, can survive acceptable levels of chlorination for potable water systems and is quite difficult to kill in evaporative cooling systems. The mixed-oxidant solution was more effective against this organism than were similar concentrations of chlorine dioxide and hypochlorous acid (Table 6). TABLE 5 COMPARISON OF ESCHERICHIA COLI KILL BY MIXED-OXIDANT AND HYPOCHLORITE SOLUTIONS Initial Oxidant* (rng/g) Cl£ (mg/G) T0 Mixed Oxidant (0.75 M NaCl; 9.5 A) 0.10 1.1 10 6 1.5 x 10 4 <1 Ca (0C1 2 ) 2 0.03 1.2 10 6 1.7 x 10 5 <1 Solution E_^ eoli CFU/ml T l min T 5 min * Oxidant measured by Na2S203 titration TABLE 6 COMPARISON OF OXIDANTS' EFFECTIVENESS AGAINST LEGIONELLA PNEUMOPHILA Total Oxidant (mg/ml) CI2 Concentration (mg/g) T0 Mixed Oxidant (0.075 M NaCl, 20 V, 7 A) 0.75 0.49 1 x 10 7 1.9 x 10 6 1.5 x 10 4 3.0 x 10 2 C10 2 0.75 0.20 lxlO7 2.0 x l O 6 1.0 x 10 3 1.0 x 10 3 HOC1 0.67 0.23 1 x 10 7 8.0 x 10 6 6.0 x 10 6 1.0 x 10 6 Solution 14 L. pneumophila CFU/ml T2 m j n T5 m ! n T15 min , Los Alamos Technical Associates, Inc. Giardia, a cyst-forming trophozoite that is parasitic in the mammalian gut, has become a serious human health concern in the U.S. in recent years. The cysts can be spread through fecal contamination of fresh water and enter municipal water treatment systems where they have proved extremely resistant to conventional chlorination treatment, especially at low temperatures. Several outbreaks of debilitating human diarrhea in urban areas have been traced to Giardia contamination of municipal water supplies. Newly proposed standards for U.S. drinking water specify less than one Giardia cyst/100 ml. To test the effectiveness of the mixed-oxidant solution against cysts, an experiment was carried out using Giardia muris, the mouse infective species. This species is slightly more difficult to kill than the human pathogen, Giardia lamblia, and is easier to maintain in culture as the mice are asymptomatic. Viability and infective potential in Giardia is shown by the live trophozoites excysting under standard incubation conditions that simulate passage through the mammalian gut. This test compared the number of organisms able to excyst when contaminated water was treated with the mixed-oxidant solution. The water conditions investigated were cold, clear water (3°C); warm, clear water (20.5°C); and cold, turbid water (3°C). In order to assess the effects of other oxidants, the free chlorine levels were kept very low. A minimum of 500 cysts were inspected for each treatment. In the cases where kill was thought to be complete, all of the approximately 4,500 cysts per treatment were scanned, for certainty. The mixed-oxidant solution was able to kill all Giardia cysts in cold and warm clear water, although the free chlorine concentrations were at the lower end of the municipal treatment range (Table 7). The total kill in cold water at 0.40 mg/5 chlorine content is especially significant as it suggests the effectiveness of short-lived oxidants. The concentration of cysts used in these tests was very high—about 4,500 cells r in 50 ml of water. Under field conditions where contamination is less severe, complete kill even in cold, turbid water seems feasible. The final three tests discussed were performed with the pilot water treatment unit shown earlier. Based on the foregoing successes in killing even very resistant microorganisms, these tests were designed to show whether a very small proportion of the mixed-oxidant solution mixed with contaminated water could kill all microorganisms and produce treated water that meets U.S. standards for drinking water for residual chlorine and maximum recommended levels for sodium and chloride content. The EPA standard for chlorine residual is 0.2- to 4-mg/B (EPA, 1986). The U.S. Public Health 15 ,.os Alamos Technical Associates, Inc. TABLE 7 EFFECT OF MIXED-OXIDANT SOLUTION ON GIARDIA EXCYSTATION Tested Water Condition Temp. °C Total Oxidant (mg/8) Cl2 Concentration (mg/8) % Giardia Viability /Excysted cells inn\ X x \ Total cells J T T T 0 10 min 30 min Clear 3 0.40 0.20 0.44 0.22 40 44 24 41 0* 19 Clear 20.5 0.44 0.22 14 57 58 60 4 12 0* 3 Turbid 3 0.35 0.18 0.74 0.37 48 42 10 49 6 44 * All "4500 cysts of this treatment were examined to verify 100% kill. Service recommends a maximum for chloride of 250 mg/8 (USPHS, 1984); the average tnste threshold is 400 mg/6 (McKee and Wolf, 1978). The National Academy of Sciences recommends a maximum sodium content in water of 200 mg/fi for persons on sodiumrestricted diets (NAS-NRC, 1973). E^ coli were successfully killed within 10 min when one volume of mixed-oxidant solution was added to 1,000 volumes of contaminated water (Table 8). The mixedoxidant solution was proded at 30 8/hr in 0.75 M NaCl using 13.4 A, 12 V dc. The calculated concentrations of interest were chlorine, 0.3 mg/8; sodium, 17 mg/8; and chloride, 12 mg/8, easily meeting the drinking water parameters. Pseudomonas aeruginosa causes eye infections in humans. American Type Culture Collection (ATCC) Strain #15442 was selected as a test organism because this strain has been identified as having broad resistance to commercial germicides and is specified for disinfectant testing by the American Organization of Agricultural Chemists (AOAC). Cell suspensions of J\ aeruginosa were successfully killed within 10 min when one volume of mixed-oxidant solution was added to 1,000 volumes of contaminated water (Table 9). The oxidant production and final parameters of water quality were the same as the preceding test, indicating successful treatment. 16 Los Alamos Technical Associates, Inc. CO ' e E1 o o o 1-H V »-H V o K m oo • F*< O .£_ '5 05 CO o t> H »•-* ^ o o Hi o »H •o o t* K X o in in 0 0• 0 0• o l-< CO O »H K • 00 CO < K o c5 w o m 4) O t* •o 0) M cd "3 C C « c t . vf c* o « o i-i o o o bo c to 3. u .c o CO CO •2 ««£ <-. --? bo c°E •<*• « o *-> ea •—« U oo 55 CO o • O £ in CO C-- o DAN 00 to W 55 O 55 O H U> J O •*-» E o «»-• CO »-*< X ^o c *-• o 03 1 PJ X C § o E «0 <D M £- o !z: "i 03 (-• o o in t- O C3 C3 o •a o 3 •a o ex w o •" 0£ •• +- c e o «• •2~3 »-< CO •• t-1 O O to 2 .3 O ca O o o W :*= D •4 £< efl O, K-4 0 £ 1 CO "O t . OJ *-• x to > ^ O C c Jtn«o 25 O o s >—« "3 < o JC H ol .1 w| c in o U CO 17 co x5 81 cr » '• 3" » ro n o OS O 3 1 cn to 33 •t Qn > o 3 2 5?r» c x s. ro Q. o c/1 » X > Q." x* 5' Oi o <-» o 2. 3 m 3 Q. w O 3. O u en 2. ida 5" 3 5" 3 r* 3 en S C a ro o. -3 -» ro •• » 3 S-O ro >-* 5 ~ 3Q. 25 O en o o^ X —. o => CD o 3 f * o CD o ro •t o O O t-* ffl 3 » 3_ CD o 5" ro a 3 O CO .1 0 -^to 03 g a en 3* o o C 3 S.J3 o ••» 3 to o a. S-. CD co ro a. 3* ra «-* W a I o >< 3 > cn O cc «1 CO »—« X r-t- o o w O CD -i to ro 55 O 55 O 55 *0 en > r W CO 173 a o O 55 > en > o> 00 • cr> co CO X 00 X X H* t-» •-* o •u o* k op * k ro •-3 c o S. 3* o CA CD ro cr CO a 2 3 O en > 00 X 3 CO 0U| 'SSJBjOOSSV |B0!Uq081 S0UJBIV S( 4.0S Alamos Technical Associates, Inc. Although not a human pathogen, Bacillus subtilis is a well-known spore forming organism. Spores, like cysts, are extremely difficult to kill by normal methods of disinfection; spores can survive in boiling water and in levels of chlorine common in municipal drinking water. R subtilis ATCC Strain #19659 was selected as a test organism because this strain is specified for use in the AOAC standard sporicide test. The cells were grown on standard nutrient agar slants for 96 hr at 30°C. Permanent slide mounts were prepared, stained, and examined to verify the extent of sporulation, which was estimated at 90% to 95% at 96 hr. Because of the known resistance of the spores, suspensions of B. subtilis spores were mixed with oxidant solutions over a wide treatment range. After 20 min, spore populations were significantly reduced, but kill was not complete (Table 10). However, one volume of mixed-oxidant solution in 500 volumes of contaminated water was sufficient to kill all spores after 20 hr. As in the two tests above, the treated water met drinking water parameters. This test will be repeated to determine the minimum, required contact time, especially by the mixture of one volume of oxidant to 1,000 volumes of contaminated water. This interval must be taken into consideration when designing a municipal water treatment system. Sufficient residence time must be allowed for total disinfection before the water is used. To summarize the effectiveness of LATA's unique water treatment system, the mixed-oxidant solution is very effective against a spectrum of microorganisms, including cysts and spores. Test organisms were selected to provide worst-case challenges. Virus tests have yet to be conducted because of the need for special facilities. Although all major human pathogens have not been tested, the results thus far indicate that potable water can be produced using a mixed-oxidant solution and that the water will meet U.S. drinking water standards and recommendations and aesthetic guidelines for residual chlorine, coliform bacteria, chloride, and sodium content. 19 ,os Alamos Technical Associates, Inc. CO CD X *-< V EH t—( V »-H V •—1 V < Z o o Pt< »-H c O o K X) in E- ^-« fo- t X O o tN to to cal o CO ^O H J CD *f o K H co «N z **• O o u f-o Z z E- rf o E- r~t K X in *r o ^o O TH t-i < z • *»• C3 **• CD X X CO X CO CO CO CO i—1 e>J c-» • c4 «S" • •a CO p jj J *-< c to 00 «# »-t »H o o eo o CO -3 M > „ o o t:~ o o o o o o I -D ** E c o tn CD CO ^ LUTION o m— p <K CNJ.5 O o o I/O o CN •a < Z cd < o z CO U EZ < XID 03 s c* *-• — bo £ O i Q W X U Z CO o o o to Tf CO -? CNJ «-l o o o ^^ c o uo c~ o o «E CO <-> E o •o o "O QJ E co in 3 *-* JC CO E O F MI E-< QJ o« o < CJ "3 bo Z en O CO CQ J en 0) o CO w \ *-t X X - «N P O < **• o CO <-< Xi 3 on o P-. X CT> \ CO O co w CJ < o c *-< e CO CO o t- uo c— o in o C5 O »-i CO 1/0 *-• o o c U ^ o E •* *-* a) o *-> c tE-< c o U z til P EH CL C3 in t- CD CD CD »—1 o .. o O co IS "x O i CJ ii X O 1 be tn o ~ .2 5 c£"-5 o 5 to o ai t J P C 3 to O en .-1 ao E- c tn O 03 +-» CO CD 0) c oo .— 3 *-• c a c *-• •t-> '5 CO •"" z en cd > r i C3 O U E ^ ^ ^ < O <£ ^X CM r-l 9—4 < o in c o U co H 20 E X> x: « a X) z < E - CQ E- Z • • • # Los Alarpos Technical Associates, Inc. REFERENCES Bader, H. and J. Hoigne, "Determination of Ozone in Water by the Indigo Method," Water Research, Vol. 15, pp. 449-456, 1981. EPA (U.S. Environmental Protection Agency), "The Disinfection of Drinking Water," Prepared for Environmental Protection Agency, PB80-112964, 1979. EPA (U.S. Environmental Protection Agency), "National Interim Primary Drinking Water Regulations," Code of Federal Regulations, 40 CFR 141, July 1986. Evans, F. L., Ill, "Ozone Technology: Current Status," In Ozone in Water and Wastewater Treatment, F. L. Evans III, Ed., Ann Arbor Science, Publishers, Ann Arbor, MI, 1972. Glaze, W. H., "Drinking-Water T r e a t m e n t with Ozone," Environ. Sci. Technol., Vol. 21 (3): 224 - 230, 1987. Grayson, M. Ed., "Ozone," In Kirk-Othmer Encyclopedia of Chemical Technology, Vol. 16, 3rd ed., John Wiley & Sons, New York, N.Y. 1981. Greenberg, A. G., ed., "Standard Methods for the Examination of Water and Wastewater," 15th ed., American Fublic Health Association, 1980. McKee, J. E. and H. F . Wolf, "Water Quality Criteria," 2nd ed., California S t a t e Water Resources Control Board, Publication 3A:160, Reprinted July, 1978. NAS-NRC (National Academy of Sciences - National Research Council), Environmental Studies Board, "Water Quality Criteria," EPA Report EPA-R3-73-033. Washington, D.C., 1973. Pendergrass, A. M., H. F. Gram, M. E. Muller, P. A. Rink, and M. W. Talley, "Electrolytic Sterilization of Potable Water on Shipboard," Final Technical Report, C o n t r a c t No. N00167-85-C-0001, SBIR, 1985. USPHS (U.S. Public Health Services), "Drinking Water Standards," Code of Federal Regulations 42 CFR 72, July 1984. 21 The Chemistry of Water Treatment Processes Involving Ozone, Hydrogen Peroxide and Ultraviolet Radiation William H. Glaze, Joon-Wun Kang and Douglas H. Chapin Environmental Science and Engineering Program School of Public Health, University of California Los Angeles, CA 90024 Abstract Advanced oxidation processes are defined as those which involve the generation of hydroxyl radicals in sufficient quantity to affect water purification. The theoretical and practical yield of OH from O3 at high pH, O3/H2O2, O3/UV and H2O2/UV systems is reviewed. New data is presented which illustrates the importance of direct photolysis in the O3/UV process, the effect of the ^02:03 ratio in the O3/H2O2 process, and the impact of the low extinction coefficient of H202 in the H2O2/UV process. Introduction This paper will summarize the chemistry of several water treatment processes involving combinations of ozone, hydrogen peroxide and ultraviolet radiation. The purpose is to show that these processes have much in common mechanistically, but there are significant enough differences to make one or the other more practical depending on water quality and water treatment goals. Advanced Oxidation Processes Ozone has been used as a chemical reagent, an industrial chemical, and an oxidant for water treatment for over eight decades (1) . Ozone is known to be a powerful oxidant and disinfectant, with a thermodynamic oxidation potenti'al that is the highest of the common oxidants. In principle, ozone should be able to oxidize most inorganic substances to their highest stable oxidation states and organic compounds to carbon dioxide and water. In actual practice, however, ozone is quite selective in its oxidation reactions. In organic chemistry it is most useful for cleavage of multiple bonds and aromatic systems, but even in these cases the rates of oxidation may be quite slow for water treatment applications. For example, ozone reacts slowly with many types of water contaminants such as alicylie taste and odor compounds as geosmin and MIB (2), aliphatic halides such as the THMs (3,4), and unactivated aromatics such as chlorinated benzenes (4) . In water treatment, ozone has been most successful for enhancing the pleasant taste of water, for aiding coagulation and filtration processes, and as a first barrier to microor1 ganisms. There is, however, a new dimension emerging in the use of ozone in water treatment. In several laboratory and pilot scale studies ozone is now being combined with hydrogen peroxide and ultraviolet radiation to produce results which have not been possible with ozone alone. The literature is replete with examples of 03/UV and 0 3 /H 2 0 2 studies in which inorganic and organic substances have been oxidized much more effectively than one can accomplish with ozone or any other common oxidant. We now understand, based on the accumulation of new information on the basic chemistry of ozone, that the success of these new processes is due to the intermediacy of the hydroxyl radical which is common to each system. We shall refer to systems such as O3/UV and 0 3 /H 2 0 2 as "Advanced Oxidation Processes" and include in this category other processes which generate the hydroxyl radical, namely ozone at high pH values, hydrogen peroxide with UV radiation, and ozone or hydrogen peroxide with other hydroxyl radical initiators such as metals and metal oxides. Historical Background Prengle and coworkers at Houston Research Inc. (HRI) were the first to see the commercial potential of the O3/UV system. HRI showed that O3/UV enhances the oxidation of complexed cyanides, chlorinated solvents, pesticides, and miscellaneous group parameters such COD and BOD (5-8) . Subsequently, the process was also commercialized by Westgate Research of Los Angeles (now ULTROX) where Zeff and coworkers further extended the applications of the process (9,10). Glaze and coworkers, especially Peyton, have examined the O3/UV process for oxidation of a number of halogenated micropollutants (3,11) and THM precursors (12) and have carried out basic studies to elucidate the mechanisms of the process (13) . Several other groups have used the O3/UV process for oxidation of a variety of organic pollutants (14-17) and the process has been taken to pilot scale for a number of applications (5,18, 19). The 03/H202 system was investigated early by Nakayama et al. (20) and Hango e_t al. (21) for wastewater treatment, and more recently by Bollyky (22), Brunet et al.(23) and Duguet et al. (24) for drinking water treatment. Duguet et al. showed that addition of peroxide enhanced the efficiency of oxidation of several organic substances, THM precursors, and also increased the rate of ozone transfer. Studies are proceeding currently in several laboratories including our own (25), and the process is being taken to pilot scale by the city of Los Angeles for removal of tri- and tetrachloroethylene in groundwater. 2 Hydrogen peroxide with ultraviolet radiation was studied by Berglind et aJL. (26) for the oxidation of humic substances, methyl isoborneol, 3,4-benzopyrene (sic), chloroform and bromodichloromethane. The process is the subject of a U.S. patent (27) but little further work has been reported. Mechanisms of Advanced Oxidation Processes Not all of the advanced oxidation systems have been well studied and their mechanisms are not fully elucidated. It appears, however, that all involve the generation of the hydroxyl radical. The present view is that the oxidizing capability of these systems is differentiated from other common oxidants such as chlorine, chlorine dioxide, etc. because of the very high reactivity of this radical. OZONATION AT HIGH pH VALUES Hydroxyl radicals were postulated by Weiss (28) as intermediates in the base catalyzed decomposition of ozone. Indirect evidence for OH radicals was presented by Hoigne and Bader (29) who showed that the mechanism of ozonation seemed to change at high pH values. The relative rate constants for high pH ozonation of pairs of organic compounds were found to be the same as those for reaction of the same compounds with hydroxyl radicals generated from radiolysis of water. Hoigne's group (30-32) and independently, Hart et al.(33-34) used advanced spectro-kinetic methods to elucidate the mechanism by which ozone decomposes in water. A complex chain mechanism was revealed that involves a series of single-electron and atom transfer processes (Figure 1) and the intermediacy of OH radicals. Staehelin and Hoigne showed that a variety of substances can initiate the chain including hydroxide, hydroperoxide, formate and ferrous ions,, and even humic substances (35). Although direct spectroscopic evidence for the OH radical in aqueous ozone systems has not been found, the indirect evidence is overwhelming that OH is the key reactive intermediate when ozone decomposes in water. In very pure water OH reacts with ozone so that the chain propagating steps shown in the circle in Figure 1 can repeat again and again. Hundreds of ozone molecules may be decomposed by a single initiation step. The result is that ozone can have a very short half-life in distilled water at pH 7 (36). In the presence of common water contaminants, for example bicarbonate, carbonate and the organic constituents of humic substances, the cycle can be broken by trapping of the hydroxyl radical, and of course, the chain may also be broken by radical-radical coupling processes. 3 Rate constants for reaction of OH with most substances are extremely large indicating that the reactions are very fast; some occur almost every time an OH radical collides with a molecule of the substance. One of the major water contaminants, bicarbonate will trap hydroxyl radicals with such efficiency that the half-life of ozone in distilled water at pH -7 increases from about 10 3 seconds in distilled water to 104 seconds in 2 iH HC0 3 ~ (36). If organic micropollutants are present when ozone decomposes they too will react with hydroxyl radicals, but they must compete with all of the other OH traps present. If the concentration of the micropollutant organics is in the micromolar range or below, they may be at a distinct disadvantage compared to matrix contaminants such as bicarbonate or humic materials, which may be present at concentrations several orders of magnitude higher (35).1 As Hoigne and coworkers have observed, the mechanism of the reaction of ozone with another substance M may involve both direct reactions of M with ozone and reaction of M with OH radicals, even if the pH of the system is near neutral (35). This is because OH-promoters such as hydrogen peroxide and superoxide ion 0 2 ~ are formed in the course of direct ozonation processes. Also, there may be contaminants in the water which act as promoters. Thus, when ozone reacts with substances in natural waters it is almost surely reacting by a combination of direct O3 and OH pathways, the relative proportions of which will depend on the various contaminants present or added. The mechanism may even become more radical in character as the reaction proceeds.2 At higher pH values there is an important factor that works against the effectiveness of ozonation processes. Hoigne has pointed out that increasing the pH will not necessarily increase the rate of OH radical destruction of a substrate because of enhanced trapping effects (29) . At p'H values 1 In the O3/H2O2 oxidation of TCE in the presence of 300 mg/L (as CaC03) of bicarbonate, we calculate that only about 4% of the transferred ozone is utilized for the destruction of 90% of 600 ug/L of TCE (25). 2 This may explain apparent discrepancies in the literature \on such questions as the destruction of THM formation potential \by ozonation, where some workers see an enhancement of THMFP by ozone and others do not (37). Under some conditions OH radicals apparently are produced by initiators present in the water and these radicals may hydroxylate benzenoid species to form THM precursors. Under other conditions the radicals are either not formed in such abundance or are quenched by other species (38). 4 greater than 10.3 carbonate is a more prevalent species than bicarbonate and the rate constant of OH with carbonate is over twenty times greater than with bicarbonate. On the other hand, ozonation is not commonly carried out at pH values above 10.3, so the role of carbonate may not be very severe as these considerations indicate. Further studies are needed to carefully document the advantages and disadvantages of using high pH conditions to enhance ozonations in waters with different alkalinity values. Figure 2 shows data from a study being carried out in our laboratory where the rate constant for ozonation of trichloroethylene is measured in a CSTR treating a high alkalinity ground water from a well in North Hollywood (alkalinity 200 mg/L as CaC03; pH 7.3; DOC 1.1 mg/L; Fe, Mn less than 0.1 ppm). As figure 2 shows, adjusting the pH from 4 to 10 has little effect on the destruction of TCE. We suspect that this behavior may be due to a cancellation of the promoting effect of hydoxide ion and the scavenging effect of carbonate vs. bicarbonate, and therefore may not be typical behavior for a water of lower alkalinity. However, the results illustrate that rate enhancements from pH changes below 10 or 11 may be minimal. OZONE WITH HYDROGEN PEROXIDE Hart and coworkers (33) and Staehelin and Hoigne (30) showed that the conjugate base of H2O2 can initiate the ozone decomposition cycle by a single electron transfer process involving the conjugate base of hydrogen peroxide H02~: H0 2 " + 03 > H0 2 + O3" (1) This initiates the decomposition of ozone resulting, in the formation of hydroxyl radical. Exploiting this effect, Duguet et al. (24) showed that the efficiency of color removal by ozone is accelerated by hydrogen peroxide. The dependence on the concentration of peroxide suggests that H2O2 is acting as a scavenger at high concentrations. In recent studies in our laboratory we are exploring the O3/H2O2 system with several substrates including chloroethenes and several taste and odor compounds. Figure 3 shows rate data for the destruction of tetrachloroethylene in a ground water from the same area in Los Angeles from which the sample was taken referred to earlier. The alkalinity of this water is somewhat\ higher than the other (300 mg/L at CaC03) but other water quality parameters are similar. In these experiments, to be reported in more detail later, the peroxide and ozone were simultaneously fed into the reactor, ozone and peroxide residuals were generally below 0.1 ppm, and ozone utilization 5 greater than 90%). The pseudo first-order rate constants show a hyperbolic dependence on peroxide with a maximum at a ratio of about one mole of peroxide per mole of ozone. This is the function expected if peroxide acts as a promoter as well as an OH scavenger. Indeed, it is know that peroxide will act as an OH radical trap as well as an initiator. The rate constant for reactions 2 and 3 are 2.7 x 10 7 M" 1 s"*1 and 7.5 x 10 9 M" 1 s" 1 respectively (39): H202 + OH H02 + OH *2 > 02~ + H20 + H+ (2) > OH" + 02~ + H+ (3) It should be noted, however, that superoxide ion 0 2 ~ is also formed in equations 2 and 3, and since superoxide also promotes the decomposition of ozone it is not clear why peroxide inhibits the decompositon of TCE at high H 2 0 2 levels. If one assumes that superoxide reacts primarily by some other pathway than with ozone, then one may derive equation 4: -d(ln[M]/[M0])/dt = k0 (4) where ko = *M k l K per[ H 202n°3]/[ H + 3 k M [M] + (k2 + k 3 Kp e r /[H + ])[H 2 0 2 ] + kitSj.] K p e r is the dissociation constant of hydrogen peroxide (1.6 x lo ) i * M ^ s t n e r a t e constant for reaction of OH with substrate, in this case TCE or PCE, and S^ symbolizes other matrix components that trap OH with rate constants k^, the most important of which are dissolved organic carbon (humic substances),bicarbonate or carbonate ion (36). Alternatively, the shape of Figure 3 may be related to the fact that the reaction is being carried out in a CSTR. That is, at high peroxide doses the rate constant is mass transfer limited. > In any case,\ the results of the laboratory scale tests on the oxidation of\TCE and PCE are so encouraging that the city of Los Angeles Ys currently sponsoring pilot scale tests to evaluate the large scale potential of the 0 3 / H 2 0 2 system for remediation of contaminated ground water in the San Fernando Valley (40). OZONE WITH ULTRAVIOLET RADIATION 6 The photolysis of ozone in wet air produces hydroxyl radicals by a two step process (41): 03 + h y (A< 310 nm) O (XD) + H20 > > OH 02 + + OH 0 ^D) (5) (6) Some workers assumed (8) that photolysis of ozone in water would proceed by a similar pathway? however Taube (42) showed, and more recently Peyton and Glaze (13,18) confirmed that this is not the case. Rather, hydrogen peroxide is formed in a process where OH radicals, if formed at all, do not escape from the solvent cage. The overall reaction is 03 + h-y + H20 > H202 (7) Equation (7) would appear to say that the O3/UV and 0 3 /H 2 0 2 processes are one and the saine: in the former one is merely forming hydrogen peroxide in situ, rather than adding it from an external source. Indeed, for some substrates that is the case as will be discussed below. For other substrates which absorb ultraviolet radiation the O3/UV process can be much more. This is illustrated by the O3/UV oxidation of tetrachloroethylene, first reported by Peyton et a_l. (3) and more recently explored in a ground water matrix by our group in Los Angeles. Tetrachloroethylene (PCE) absorbs ultraviolet radiation at 254 nm only weakly, but sufficiently so that direct photolysis is a significant contributor to the overall decay of PCE when the compound is exposed to ozone and 254 nm radiation in a CSTR reactor. Figure 4 is a plot of pseudo firstorder rate constants for a series of runs where the ozone dose was varied while keeping the UV dose constant. For a given UV dose the data approximately fit a simple relationship k0 = kp + koxDn = kp + k' (8) where kp is the direct photolysis constant, k o x is related to the constant for OH radical reaction with PCE, D is the ozone dose rate, and n is a coefficient with a value near unity (3). The value of k p obtained from an experiment in which D was zero (only oxygen was used) is in good agreement with the extrapolated value from Figure 4. Similar experiments^ were carried out with trichloroethylene (TCE) with markedly\different and revealing results. Figure 5 shows that the 03/UV oxidation of TCE is only weakly dependent on the UV flux. The extrapolated value at zero ozone dose is in good agreement with the rate constant 7 obtained in the "UV only" experiments. The TCE and PCE data from these experiments demonstrate what Prengle and coworkers claimed years ago(8): that the 03/UV process is, at the same time, an oxidation process and a photolysis process. Figure 6 illustrates the various elements of the process including direct ozonation, decomposition of ozone (OH radical chemistry) and photolysis of M and hydrogen peroxide. The relative importance of these processes will depend on an extraordinary number of factors including: the intensity and wavelength of the UV radiation, the ratio of 03:UV doses, the concentration of M, promoters and radial traps, and others. When a substance absorbs strongly in the UV region large fluxes of UV radiation will accelerate the destruction of the substance. This is the case for PCE and presumably for other UV absorbing substances such as aromatic halides. For some photolytically labile substances such as some pesticides, kp is so large that little is to be gained from using ozone. On the other hand, when the substance of concern is not photolyzed directly with much efficiency, the use of UV radiation to generate hydrogen peroxide makes little sense.3 In such cases it is preferable to add hydrogen peroxide from an external source. Metering of peroxide into a water stream is a trivial task compared to the use of UV lamps with their attendant problems of clouding and flux decay especially for large water treatment plants. Our view is that both processes should be considered in a feasibility study, but except when direct photolysis is a major factor, the O3/H2O2 process is heavily favored. HYDROGEN PEROXIDE WITH ULTRAVIOLET RADIATION In principle, the most direct method for the generation of hydroxyl radicals is through cleavage of hydrogen peroxide, a relatively inexpensive and readily available chemical intermediate. Photolysis of hydrogen peroxide is known to yield hydroxyl radicals by a direct process, i.e. with a quantum yield of two OH formed per quantum of radiation absorbed (43): 3 Many applications of the ozone/UV process, including some current commercial realtors, use UV intensities which are extremely high and costly^ There is an optimum ratio of UV flux (in Einsteins/min):ozone dose (in moles/min) for each system, but in the absence of much direct photolysis the ratio is probably less than 0.5. In a study of the O3/UV oxidation of THM precursors the optimum ratio was 0.3 (18). 8 H202 + hV > OH + OH (9) Unfortunately, the molar extinction coefficient of hydrogen peroxide at 254 nm is only 19.6 M _ 1 s"1 (43), which is exceptionally low for a primary absorber in a photochemical process. By comparison, the value for ozone is 3300 M - 1 -1 cm . This means that in order to generate a sufficient level of OH radicals one must have a rather high concentrtion of hydrogen peroxide in the medium. Figure 7 shows data from a kinetic study where hydrogen peroxide is being metered into a CSTR at a rate of 10 mg/min while photolyzing the solution with three 13 watt low pressure mercury arc lamps (greater than 90% UV energy at 254 nm) . Trichloroethylene, which was spiked into the original solution at approximately 500 ppb, and residual hydrogen peroxide were monitored as the reaction proceeded. Figure 7 shows that TCE is decomposed at a reasonable rate compared to the 03/H202 data in Figure 3, but hydrogen peroxide accumulates to unacceptable levels. We conclude that the H202/UV is unlikely to be a practical process for drinking water treatment until this problem is solved; however, for wastewater treatment or other purposes it might be useful. SUMMARY OF HYDROXYL RADICAL GENERATING PROCESSES Table 1 is a summary of the chemistry involved in the generation of hydroxyl radicals from the four processes considered in this review. As noted above, the stoichiometric yield of hydroxyl radicals is greatest from the photolysis of hydrogen peroxide. As Table 2 shows, however, ozone photolysis yields more radicals in practice because of the higher molar extinction coefficient of ozone compared to hydrogen peroxide. Of the four processes, the 0 3 /H 2 0 2 process should have a high yield of OH radicals, is most amenable to adaptation in existing water treatment plant designs, and should be relatively cost effective. The use of ozone at high pH values may be comparable in cost/effectiveness but there is little field data on this process. The O3/UV process will be difficult to adopt on a large scale but may be useful for small water and waste water treatment plants, particularly when the substrates of concern are strong UV absorbers. Acknowledgement The author is grateful to the City of Los Angeles Department of Water and Power for support of this work, partially with funds supplied by the U.S. Environmental Protection Agency through Cooperative Agreement CR-813188, and to E. Marco Aieta, Rhodes Trussell and Carol Tate of James M. Montgomery 9 Consulting Engineers for useful discussions. The original work was performed by Joon-Wun Kang and Douglas Chapin. This article has not been subjected to review by EPA. Therefore, it does not necessarily reflect the views of the agency, and no official endorsement should be inferred. References 1. M. HORVATH, L. BILITZKY and J. HUTTNER, Ozone, Elsevier, Amsterdam, 1985. 2. S. LALEZARY, M. PIRBAZARI, and M.J. MCGUIRE, "Oxidation of Five Earthy-Musty Taste and Odor Compounds", Jour.AWWA, 78:3:62(1986). 3. G.R. PEYTON, F.Y. HUANG, J.L. BURLESON and W.H. GLAZE, "Destruction of Pollutants in Water with Ozone in Combnation with Ultraviolet Radiation. 1. General Principles and Oxidation of Tetrachloroethylene, Environ. Sci. & Technol. 16:448(1982). 4. J. HOIGNE AND H. BADER, "Rate Constants of Reactions of Ozone with Organic and Inorganic Compounds in Water. I. NonDissociating Organic Compouds, Water Research, 17:173(1983). 5. R.L. GARRISON, C.E. MAUK and H.W. PRENGLE, JR., "Advanced Ozone System for Complexed Cyanides", in First International Symposium on Ozone for Water and Wastewater Treatment; R.G. Rice and M.E. Browning, eds., International Ozone Institute, Syracuse, N.Y., 1975, p. 551. 6. H.W. PRENGLE, JR., C.G. HEWES, III AND C.E. MAUK, "Oxidation of Refractory Materials by Ozone with Ultraviolet Radiation, in Second International Symposium on Ozone Technology, R.G. Rice, P. Pichet and M.-A. Vincent, eds., International Ozone Institute, Syracuse, N.Y., 1976, p. 224. 7. H.W. PRENGLE, JR. and C.E. MAUK, "Ozone/UV Oxidation of Pesticides in Aqueous Solution", in Ozone/Chlorine Dioxide Oxidation Products of Organic Materials, R.G. Rice and J.A. Cotruvo, eds., Ozone Press International, Cleveland, OH, 1978, p. 302. \ 8. H.W. PRENGLE, JR., "Evolution of\the Ozone/UV Process for Wastewater Treatment", Presented afcx IOI/EPA Colloquium on Wastewater Treatment & Disinfection with Ozone, U.S. Environmental Protection Agency, Municipal Environmental Research Laboratory, Cincinnati, OH, Sept. 15, 1977. 10 9. E. LEITUS, E.H. BRYAN, J.D. ZEFF, D.C. CROSBY and M. SMITH, "An Investigation into the Chemistry of the UV-Ozone Purification Process", Presented at the 4th World Ozone Congres, Houston, Texas, Novmeber 27-29, 1979. 10.WESTGATE RESEARCH CORPORTION, "The Continued Investigation into the Chemistry of the UV-Ozone Water Purification Process", Proposal Submitted to National Science Foundation, February 28, 1978; J.D. Zeff, Private Communication. 11. W.H. GLAZE, G.R. PEYTON, F.Y. HUANG, J.L. BURLESON and P.C. JONES, "Oxidation of Water Supply Refractory Species by Ozone and Ultraviolet Radiation", U.S. Environmental Protection Agency, Municipal Environmental Research Laboratory, Cincinnati, OH, EPA-600/2-80-110, August, 1980. 12. W.H. GLAZE, G.R. PEYTON, S. LIN, F.Y. HUANG and J.L. BURLESON, "Destruction of Pollutants in Water with Ozone in Combnation with Ultraviolet Radiation. 2. Natural Trihalomethane Precursors, Environ. Sci. & Technol. 16:454(1982). 13. PEYTON, G.R. and W.H. GLAZE, "Mechanism of Photolytic Ozonation", in Photochemistry of Environmental Aquatic Systems. R.G. Zika and W. J. Cooper, eds., ACS Symposium Series 327, Washington, DC, 1986, pp. 76-88. 14. M.K. LEE, G.G. SEE and R.A. WYNVEEN, "Reaction Kinetics of UV/Ozone with Organic Compounds in Hospital Wastewater". Presented at the Symposium on Advanced Ozone Technology, Interntional Ozone Institute, Toronto, ONT, Nov. 16-18, 1977. 15. E.S.K. CHIAN and P.P,K. KUO, "Fundamental Study of the Post Treatment of RO Permeates from Army Wastewaters", Second Annual Summary Report to U.S. Army Medical Research and Development Command, Contract No. DAMD 17-75-C-5506, 1976. 16. P.P.K. KUO, E.S.K. CHIAN and B.J. CHENG, "Identification of Eng Products Resulting from Ozonation of Compounds Commonly Found in Water", in Ozone/Chlorine Dioxide Oxidation Products of Organic Materials. R.G. Rice and J.A. Cotruvo, eds., Ozone Press International, Cleveland, OH, 1978, p. 153. 17. E.G. FOCHTMAN and J.E. HUFF, 'Ozone-Ultraviolet Light Treatment of TNT Wastewaters", in Second International Symposium on Ozone Technology, R.G. Rice,\p. Pichet and M.-A. Vincent, eds., International Ozone Institute, Syracuse, N.Y., 1976, p. 211. \ 18. W.H. GLAZE, G.R. PEYTON and B. SOHM, 'Pilot Scale Evaluation of Photlytic Ozonation for Trihalomethane Precursor Removal", Report of Cooperative Agreement CR--808825, U.S. 11 Environmental Protection Agency, Municipal Environmental Research Laboratory, Cincinnati, OH., June , 1984. 19. F.C. FARRELL, J.D. ZEFF, T.C. CRASE and D.T. BOYLAND, "Development Effort to Design and Describe Pink Water Abatement Proesses", Final. Technol. Report No 1701 to U.S. Army Armament R&D Command, Dover, NJ, August, 1977. 20. S. NAKAYAHA, K. ESAKI, K. NAMBA, Y. TANIGUCHI, and N. TABATA, "Improved Ozonation in Aqueous Systems", Ozone Sci. & Engng. 1:119 (1979). 21. R.A. HANGO, L.J. BOLLYKY and F. DOANE, "Wastewater Treatment for Re-Use in Integratd Circuit Manufacturing", Wasser-Berlin-81, 5 Ozon Weltkongress, Colloquium Verlag, Berlin, 1981, p. 304. 22. L.J. BOLLYKY, "Pilot Plant Studies for THM, Taste and Odor Control Using Ozone and Ozone-Hydrogen Peroxide", in The Role of Ozone in Water and Wastewater Treatment. Proceedings of the Second International Conference, Edmonton, AL, April 28-29, 1987, p. 211. 23. R. BRUNET, M. M. BOURBIGOT and M. DORE, "Oxidation of Organic Compounds Through the Combination Ozone-Hydrogen Peroxide", Ozone Sci. & Engng., 6: 163 (1984). 24. J. P. DUGUET, E. BRODARD, B. DUSSERT and J. MALLEVIALLE, "Improvement in the Effectiveness of Ozonation of Drinking Water Through the Use of Hydrogen Peroxide", Ozone Sci. & Engng., 7:241 (1985). 25. W.H. GLAZE, J.-W. KANG AND E. M. AIETA, "Ozone-Hydrogen Peroxide Systems for Control of Organics in Municipal Water Supplies", in The Role of Ozone in Water and Wastewater Treatment, Proceedings of the Second International Conference, Edmonton, AL, April 28-29, 1987, p. 233. * 26. L. BERGLIND, E. GJESING and E. SKIPPERUD JOHANSEN, "Removal of Organic Matter in Water by UV and Hydrogen Peroxide". In Oxidation Techniques in Drinking Water Treatment, W. Kiihn and H. Sontheimer, eds., U. S. Environmental Protection Agency, EPA-570/9-79-020, 1979, pp. 510-523. 27. E. KOUBECK, "Oxidation of Refractory Organics in Aqueous Waste Streams by Hydrogen Peroxide and ultraviolet Light", U.S. Patent Nr. 4, 012, 321 (1977). \ 28. J. WEISS, "The Radical H0 2 in Solution", Trans. Faraday S o c , 31:668 (1935). \ 29. J. HOIGNE and H. BADER, "Ozonation of Water: Role of 12 Hydroxyl Radicals 109:4216 (1975). as Oxidizing Intermediates", Science, 30. J. STAEHELIN and J. HOIGNE, "Decomposition of Ozone in Water: Rate of Initiation by Hydroxide Ion and Hydrogen Peroxide", Environ. Sci. & Technol., 16:676 (1982). 31. R.E. BUHLER, J. STAEHELIN and J. HOIGNE, "Ozone decomposition in Wter Studied by Pulse Radiolysis. 1. HO2 /0"2~ and HO3/O3" as Intermediates", J. Phys. Chem., 88:2560 (1984). 32. J. STAEHELIN, R.E. BUHLER and J. HOIGNE, "Ozone decomposition in Water Studied by Pulse Radiolysis.2. OH and HO4 as Chain Intermediates", J. Phys, Chem., 88:5999 (1984). 33. L. FORNI, D. BAHNEMANN and E.J. HART, "Mechanism of the Hydroxide Ion Initiated Decomposition of Ozone in Aqueous Solution", J. Phys. Chem., 86:255 (1982). 34. K. SEHESTED, J. HOLOMAN, E. BJERGBAKKE and E.J. HART, "Ultraviolet Spectrum and Decay of the Ozonide Ion Radical, 0 3 ~, in Strong Alkaline Solution", J. Phys. Chem., 86:2066 (1982) . 35. J. STAEHELIN and J. HOIGNE, "Decompositon of ozone in the Presence of Organic Solutes Acting as Promoters and Inhibitors of Radical Chain Reactions", Environ. Sci. & Technol., 19:1206 (1985). 36. J. HOIGNE and H. BADER, "Ozone Hydroxyl Radical-Induced Oxidations of Organic and Organometallic Trace Impurities in Water", in Organometals and Orqanometalloids: Occurrence and Fate in the Environment, r. R. Brinckman and J.M.Bellama, eds., ACS Symposium Series 82, American Chemical Society, Washington, DC, (1978), pp. 292-313. 37. J.M. SYMONS et al., "Treatment Techniques for Controlling Trihalomethanes in Drinking Water", U.S. Environmental Protection Agency, Drinking Water Research Division, Cincinnati, OH, EPA-600/2-81-156, September, 1981, pp. 125-128. 38. B. LEGUE, J.P. CROUE, D.A. RECKHOW and M. DORE, "Ozonation of Organic Precursors: Effects of Bicarbonate and Bromide". In Proceedings of the International Conference on The Role of Ozone in Water and Wastewater Treatment. R. Perry and A. E. Mclntyre, eds., Selper Ltd, London, (1985), pp. 7339. H.S. CHRISTENSEN, K. SEHESTED and H. CORFITZAN\ "Reactions of Hydroxyl Radicals with Hydrogen Peroxide at\Ambient and Elevated Temperatures", .T. Phys. Chem., 86:1588 (1982). 40. E. M. AIETA, JAS. M. MONTGOMERY, CONSULTING ENGINEERS, 13 Pe.sadena, CA (personal communication) . 41. H. OKABE, Photochemistry of Small Molecules, Interscience, New York, NY, (1978), p. 244. Wiley- 42. H. TAUBE, "Photochemical Reactions of Ozone in Solution", Trans. Faraday S o c , 53:656 (19 57). 43. J.H. BAXENDALE and J. A. WILSON, "The Photolysis of Hydrogen Peroxide at High Light Intensities", Trans. Faraday S o c , 53:344 (1957). 44. A. L. LAZRUS, G.L.KOK, S.N. GITLIN, J.A. LIND and S.E. MCLAREN, "Automated Fluorometric Method for Hydrogen Peroxide in Atmospheric Precipitation", Anal. Chem., 57:917-922 (1985) 14 I LEGEND OF FIGURES FIGURE 1. Scheme showing the principal species in the decomposition of ozone in pure water initiated by hydroxide ions (after Staehelin et al., reference 32) . FIGURE 2. Effect of pH on the ozonation of trichloroethylene (TCE) in North Hollywood Well No. 26 water. Bicarbonate alkalinity: 200 mg/L; TOC 1.1 mg/L; pH adjusted upwards with sodium hydroxide, downward with hydrochloric acid; 70 liter CSTR with ozone from pure oxygen. FIGURE 3. Effect of hydrogen peroxide on the pseudo first-order rate constants of oxidation of TCE in North Hollywood Well No. 14 water. Alkalinity: 300 mg/L; 70 liter CSTR with ozone from pure oxygen, 03 scale is dose rate, utilization > 90%. FIGURE 4. Effect of ozone and UV dose rates on the photolytic ozonation of perchloroethylene (PCE) in North Hollywood Well No. 14 water. Rate constants (s _1 ) multiplied by 10^; UV dose in watts/L at 254 ran calibrated by chemical actinometry. FIGURE 5. Effect of ozone and UV dose rates on the photolytic ozonation of trichloroethylene (TCE) in North Hollywood Well No. 14 water. Rate constants (s _1 ) multiplied by 10^; UV dose in watts/L calibrated by chemical actinometry. FIGURE 6. Schematic diagram of the elements of mass and photon transfer, and chemical processes involved in the O3/UV process. FIGURE 7. Pseudo first-order plot for destruction of TCE by H 2 0 2 /UV process in North Hollywood Well No. 14 water. Reaction carried out in 70 liter CSTR with feed rate of 10 mg H 2 0 2 per minute. Residual peroxide by horseradish peroxidase fluorimetry (44). 15 TABLE 1 THEORETICAL AMOUNTS OF OXIDANTS AND UV REQUIRED FOR FORMATION OF HYDROXYL RADICAL IN OZONE-PEROXIDE-UV SYSTEMS Moles of Oxidant Consumed per Mole of OH Formed SYSTEM 03 UV X H202 (0.5) 2 OZONE-HYDROXIDE ION 3 1.5 OZONE-UV 1.5 0.5 OZONE-HYDROGEN PEROXIDE3 1.0 — 0.5 •'-Moles of photons (Einsteins) required for each mole of OH formed; 2 Hydrogen peroxide formed in situ (13,42); 3 Assumes that superoxide formed in primary step yields one OH radical per 0 2 ~ which may not be the case in certain waters. 16 TABLE 2 THEORETICAL FORMATION OF HYDROXYL RADICALS FROM PHOTOLYSIS OF OZONE AND HYDROGEN PEROXIDE MOLAR ABSORBTIVITY 254 (M-1 cm" 1 ) STOICHIOMETRY OH RADICALS FORMED 1 PER INCIDENT PHOTON H202 20 H202 > 20H 0.09 03 3300 30 3 > 20H 2.00 1 Assumes 10 cm pathlength; quantum yield as predicted from stoichioiaetry; [0 3 ] and [H 2 0 2 ] at 1 x 10~ 4 M. 17 9.5 -8.5 I n (TCE/TCEo) -1 - o PH 18 >K PH a PH 4 -1.5 -2.5 18 15 Tiwe ( n i n ) 25 2 8 Psuudo F i r s t Order B a t e C o n s t a n t x IB ( 4 ) CO in WW O • «-* tO •* CT> i i A -^ vv^» to 63 1 N 1 A CO N3 • 1 1 1 1 1 OS. \ 0 CD N CD • •• »fe ts 0 0\ a (A (0 X 0.6 -peroxi ,. -... \ \° CD * ——i 8 1.2 -peroxi de/woles Ozone 1 ® oN c° o r- H» - t* • cr> J • j 1 i 1.2 1.4 N • -m .- 1 .,,—,- .._ i J Pseudo First Order Rate Constant x 10 (4) CO tsj -- Jk - - o N 0 3 CO C7» •• o w CO W m 03 -- Z f I 3 3 (9 l1* . 00 * X + 0 CD • CD • CO GO E \ E- CO • I-* 14 JC \1 tn -j E \1 t- t- V Pseudo First Order Rate Constant x 19 (4) CO cs o PO -• A •- CO .—1—— 1 — N3 h* N H* N •A. en CO CO N 1 — i — — 1 — — 1 — — 1 — CO N3 « N 0 3 a en -o M n ^ co (9 3 (4 i C3 3 • • < • 3 N cr> 63 + eg • • cn CO CO 3C \ f X -* s X f D CO • H» *J3 3C \ f JT ELEMENTS OF THE OZONE/ULTRAVIOLET RADIATION PROCESS MASS TRANSFER AND PHOTON TRANSFER OZONE £. MASS TRANSFER 4 UV SOURCE SOURCE WATER M (SUBSTRATE) S (RADICAL TRAP) P (PROMOTER) ± PHOTON TRANSFER * SOLUTION CHEMICAL PROCESSES PHOTOLYSIS OF OZONE DECOMP. OF OZONE PHOTOLYSIS OF PEROXIDE a»?™«fc« OH DIRECT REACTION O3/M DIRECT PHOTOLYSIS OFM RADICAL REACTIONS OH/M r-l E o & o c rJ o o T l v-l ' 1.1 id E M oo »J c C a> o o o o o o o o o o o O O r-i t-l o o »-l o o O o H o o u. o o r-l c o o Q UI a: lL o u CO « co o n e e w u 3 co 111 W O •H E c (0 60 U OJ o -H P. X X O H c -H 6 o c c 1-1 E o CNl CNl c c c c •H T-t -H •w T-i E o B o E o B o B o vO vO rH vO .-i O O c 6 z C •H e E o O vO 0) o o t-t o E o CM cu r0 o r-» CO > > C O O •H i-> >-i O -H to e u l-l C CU 3 CO o r-. O IN. O O O vO O I-N CN) O cu O CO 3 to to CU CO o o o o m O E P. 60 O 3 •o o o p< u cu N •H TJ -rH cu t i <D »J X cu .a o CU E o o U-l O o CU O M a) a . co 3 M cu - o N C -H D iJ C E c •H -H E 6 E c •H E c •w E c •H <0 U r-i .a X! E CNl 0 E c •H o E CN -r< 1 3 H rl X CU o 4J r-l CO 0) 3 M-l w T3 •H CO CU CO N U I •o -H X o O r-l CU D . CJ v ^ o c o > CJ I-N. CO (0 ai *J JO CU i-l w o H o a o e o -o 3 cu CO re to to c o E o •o 3 cu CO to (0 c o E o •o 3 CU CO A.I CO CO <0 C CO o E o •a 3 CU CO P« c o E o •a a cu co P< CO (0 C o E o •o 3 CU co P~i CO CO C o e o •a 3 CU CO CO « c o e o •o 3 CU co CU c o -r\ 60] CU - J CO r-H r-l -i-l X 3 O U o. ex o E to 3 O CU »-i c CU D. CO » CO • H •M u u cu r o -l 3 w cu >4-l o >N to CI z to CX B CO rH 00 c cu u u 3 1 a. o x c V o •H ' E o .n o c n o u -H T-I '" E CO U 60 *-> C C -rl 0> > O -H CO E w •rl C 0} oo •U O 4) c > O O M 2 10 CD U M C 3 (0 W X) E o TI •H H r-« P. X 01 X O o o o o o o o o o o c c >-l "H E o o vO VD O O o o o o o o o o o o rH r-l CM c c c o o t-I r-l C •H tH •H •rH •H c -H c x. E o E o E o E o E o •H CM vO vO .-1 vO tH O o E E O vO O vO o o u o •H <4-l o 01 x> c o o u u to > •H -rl cd E *J x) <1J 0) u > M : 3 CO vO O I-O r-l O vO o CM o O cu CO p c a) to (0 o o c o C o • L) C_> r* E 01 P. 00 <d o P c o x» o M P< ^ 0> N -H XJ -rl o C P 0) O XJ CU a) o XJ ? u cO ( X CO p 01 X o >-• X> a) x) u-i E -iH co o O) •H H «J N C x) -H X I c -H E m E u-1 C -rl C c •H E 6 •H E m in c •H E IO «n M -C X <r <r »-< U CM c c <M •rl •H E E to o in u a) u o o <u m w U CJ CO ft x> XJ Ti >-> tO d cd in a) tx •H o ^ C o o o o r l t-1 > to to C 0) 4 J JO to o 0) H M O :E r-l O ~3 X co to o o c 6 -rl o 60 X) P a) (0 Pi P i. CO (0 to C O <0 (0 O E o x> -rl 60 P P 0) (0 p* c b CO 10 to C rt w to CO o o •r\c. E o 6C X) p p 0) CO p, M 01 <0 CO TO O c o - cH e o 6C X) P p aUi a) ( 0 cd P* en cO co ( 0 C o o - cH E o 60 XJ P p M o> 01 (0 p. cO CO CO C cO CO o o >-l c E o er X) p 01 en P. p P 01 CO en cO co to C O o - Cr l e 6f o x» P p M a) a> CO CO p. to crj C O C o X) p 0) to Pi CO in o 0 -H OC P M a> CO en tO co CO c o o • CH E 60 O X) P ai (0 Pi P U 01 CO I in CO r-| CO - r l tH r-t D. .c P a O <u o M c E oo o P o >H 01 60 CD rJ ll c ai a. en tO T-I • r l Vi M 0 ) O) t-H r H 00 ai 5 o « «-. 55 to o. B tO to IM o C 0) Vi >-. p o P^ X U) O C ADVANCED OXIDATION PROCESSES FOR TREATMENT OF GROUNDWATER CONTAMINATED WITH TRICHLOROETHYLENE AND TETRACHLOROETHYLENE: LABORATORY STUDIES William H. Glaze and Joon-Wun Kang, Environmental Science & Engineering Program, School of Public Health, UCLA, Los Angeles, California 90024 ABSTRACT The oxidation ethylene (or of trichloroethylene perchloroethylene (TCE) - PCE) and was tetrachlorostudied in a stirred sparged reactor with various dose rates of ozone and hydrogen peroxide. The results show that hydrogen peroxide accelerates the oxidation of TCE and PCE spiked into a ground water taken near Los Angeles, California. dose rates above 0.7 transfer limited. At peroxide:ozone (w/w) the process appears to be mass The presence of high levels of bicarbonate ion in the groundwater is shown to significantly lower the efficiency of TCE and PCE removal by the 0 3 /H 2 02 process suggesting that softening prior to oxidation may improve the process even further. INTRODUCTION Groundwater contamination tetrachloroethylene by trichloroethylene (TCE) , (PCE), and other industrial and agricul- tural chemicals is now a matter of international concern. The U.S.E.P.A. recently proposed Maximum Contaminant levels for TCE and seven other contaminants in drinking water and a standard for PCE may be\forthcoming (1). the Safe Drinking Water^ mandate, EPA In accordance with also specified two technologies as Best Available Technology (BAT) for treatment 1 of water containing these substances: granular activated carbon filtration. air stripping and Some have objected to these technologies on the basis that they merely transfer the problem from one medium (water) to another (air or GAC). Oxidation processes offer the option, at least in principle, of completely destroying organic contaminants. Of the 't oxidants currently available, ozone is attracting the most attention. This is due to its high thermodynamic oxidation potential (2.07 volts) and the apparent lack of hazardous byproducts (2) . However, neither ozone nor any other oxidant has proven itself as a BAT process for removing synthetic organic compounds from ground water. iency and to enhance To overcome this defic- its effectiveness for oxidation of organics, modifications of traditional ozonation have been investigated in our bench-scale laboratory tests. Each of the processes studied, which we refer to as advanced oxidation processes hydroxyl radical (3,4), involve the generation' of the (OH), a very active intermediate which generally has far greater oxidizing power than ozone. constants for reaction of OH with organic species Rate are commonly in the range of 10?-1010 M _ 1 s _ 1 (5). Four types of advanced oxidation processes are being studied. These include: ozone at various pH values (03/pH), ozone with 2 hydrogen peroxide (03/H202)/ ozone with ultraviolet radia- tion (O3/UV), and hydrogen peroxide with ultraviolet radiation (H202/UV\. This paper describes an evaluation of the first two processes (03/pH and C>3/H202) for the oxidation of TCE and PCE in a contaminated groundwater obtained from two City of Los Angeles Department of Water and Power (LADWP) North Hollywood wells. The results, combined with pilot- scale studies described in the following paper (6), show that the ozone:hydrogen peroxide processs should be considered as a candidate for Best Available Technology for TCE/PCE treatment. EXPERIMENTAL Reaction apparatus. Figure 1 shows the schematic diagram of the 03/H202/UV experimental system. Ozone was generated from oxygen with a single tube OREC generator (corona discharge type), typically at a flow rate of 1.0 L/min and at a tube current setting so as to give a desired dose rate. panel valves (needle, 3-way, Control and 5~way valve) allowed one to r divert the ozone stream through two tandem bubblers for ozone analysis or alternately divert the ozone off-gas from the reactor through the same bubblers. When the analysis system is not in use, ozone off-gas is thermally decomposed before \ \ exit into a vented hood. All fittings, valves, and tubing \ were limited to stainless steel,\ glass, and teflon. The reactor used in these studies is \a cylindrical 70 liter (liquid volume) CSTR designed according to the principles 3 described by Yocum (7). The reactor is a 36 inch high by 13 inch O.D. stainless steel vessel with a built-in sparger for ozone introduction, a variable speed stirrer (usually operated at 500 rpm), internal baffles at the quadrants to facilitate mixing, and four 2-inch diameter symmetrically located circular ports into each of which can be fitted a quartz tube for a UV lamp. The UV ports were sealed off with stainless steel plates in this study. Test Samples. Groundwater used for all of the 03/H 2 0 2 runs, except to study the effect of bicarbonate alkalinity, was collected from the City of Los Angeles Department of Water and Power North Hollywood Well No. 14 or Well No. 26. The water was transported to UCLA in a 55-gallon polyethylene drum. Typical analysis of the groundwater, for Well No. 14 or 26 respectively, was: alkalinity, 300 mg/L and 200 mg/L (as CaC0 3 ), respectively; pH 7.2-7.4; TCE and PCE, 50 and 5 ug/L, respectively; and TOC 1.1 mg/L. Analytical methods. Ozone is analyzed in the gas phase by trapping in an borate-buffered potassium iodide solution (8). The concentration of resulting iodine is determined colorimetrically at 352 ran on a Spectronic 710 spectrophotometer (Bausch & Lomb, Rochester, N.Y), \which is previously calibrated by standard iodine solution. - Ozone in the liquid phase is determined by the indigo method (9) . 4 Each ozone sample was added to a 40 ml vial which contained an appropriate stock concentration reagent expected. of depending potassium on the indigo trisulfonate concentration of ozone The absorbance difference between sample and blank was measured at 600 nm. An extinction coefficient of 2 0,000 L Mol"1 cm"1 (9) was used for calculation of the concentration of residual ozone. Concentration of residual hydrogen peroxide either was Masschelein fluorescence determined (10) or method the the cobalt method horseradish described feeding by by solution of peroxidase-catalyzed Lazrus, (usually et al. (11). Hydrogen peroxide 0.12 N) was prepared from a reagent grade 30% stock solution (Fisher Scientific) and v/as analyzed by the AOAC Method (12). A method for analysis of TCE and PCE modified from EPA Method 501.2 consisted of microscale liquid-liquid extraction using pentane or hexane (American Burdic & Jackson brand for THM analysis) with a water to extractant volume ratio of 2:1. Two different gas chromatograph TCE/PCE analysis. (GC) models were used for Most of the analytical work was performed on a Varian 3700 GC with Ni 6 3 electron capture detector (ECD), a glass column (12' x 1/4" O.D., 10% squalane), and a 5% methane and 90% argon gas mixture as carrier gas. A Schimadzu Chromatopac C-R3A electronic/printer integrator was connected to the Varian GC to collect data and compute sample concentrations. Later sample analyses were carried out on a Perkin-Elmer Model 8500 GC using splitless injection and a Ni 6 3 ECD. A fused silica wall coated open tubular column (DB-5, 30 m x 0.32 mm I.D.) supplied by J&W Scientific was used. Oven temperature was programmed from 40°C to 220°C at 10°C/min. Helium gas (99.995%) and 5% methane/95% argon gas mixture were used for carrier and make-up gas, respectively. Hexane was used as extractant for this splitless injection mode to optimize the solvent effect. used for all GC analyses was The internal standard 1,2-dibroraopropane (DBP) . Quality control features of EPA Method 501.2 were used for preparation of calibration standards for the extraction method. Procedures. For each run, groundwater was pumped into the CSTR and filled up to a guide level of 70 L. Saturated solutions of TCE and PCE were prepared separately by stirring pure compounds in contact with distilled water. After analysis, these stock solutions were used to prepare aqueous solutions of known concentrations of TCE and PCE that were r spiked into the reactor so as to give target initial TCE and PCE concentrations of approximately 500 and 50 ug/L, respectively. After a few minutes of mixing, oxygen gas was introduced into the CSTR at a desired flow rate.^ To detect any system leaks, another rotameter was installed\at the gas stream exit. Flow rate of the exit stream was then\ compared to the inlet flow rate. At time zero, ozone generation was started using pre-set conditions for the ozone generator. 6 If hydrogen peroxide was included in the run, it was added simultaneously with the ozone using a calibrated feed pump supplied by Mec-O-Matic Company. For some runs, the pH of the groundwater sample was adjusted prior to oxidation using either a NaOH solution or H 2 S0 4 solution. Duplicate samples of the CSTR contents were taken for TCE and PCE analysis at five-minute intervals, beginning at time zero and ending 25 minutes later. Two drops of 1% sodium thiosul- fate were present in each 4 0 ml vial before the groundwater samples were added. The vials were filled head-space free and sealed with screw caps with PTFE-coated liners. Samples were stored in a refrigerator (organic free) at 4°C prior to extraction. measure Samples were taken at the same time intervals to concentrations of peroxide as described above. residual ozone and hydrogen Ozone off-gas was trapped in the BKI-contained bubbler and the amount of ozone consumed in the reactor was calculated from the concentration of ozone in r the feed gas and the concentration of ozone in off-gas. Measurement of Ozone Kass Transfer for CSTR. The reactor was filled with water taken from North Hollywood well No. 14 and ozone flow started at the same flow rate as before (1.0 \ L-min -1 ). Samples were withdrawn sequentially from the reactor and quenched with a solution of indigo trisulfonate\ then the absorbance of the solution was measured as usual." 7 RESULTS & DISCUSSION Ozone system. Hoigne and Bader have reported that the rate constants for direct reaction of ozone with TCE and PCE are 17 ± 4 M _ 1 s-1 "and <0.1 M" 1 s"1 respectively (13). This means that a steady state concentration of 5 mg/L (1 x 10~ 4 M) of ozone would be required for 95% oxidation of TCE within a thirty minute contact time, assuming pseudo first order kinetics. For PCE the rate is expected to be at least an order of magnitude slower. It might be concluded, therefore, that direct reaction of ozone will not be sufficiently rapid to be a practical decontamination method for PCE but for TCE it may be worth exploring. It is now recognized, however, that calculations based on such basic rate data are of little value in determining the prospects of using ozone for water treatment objectives (14). Few ozonation processes occurring in a natural water occur only by interest. direct reaction of ozone with the substrate of In natural waters ozone reacts by two mechanisms: direct reaction of the O3 molecule, for example, by addition of O3 to the carbon-carbon double bond of TCE or PCE, and reaction with the hydroxyl radical, formed by the decomposition of ozone (14). Both types of reactions are expected to occur in natural waters where there are naturally occurring 8 electron transfer agents present tions) that initiate ozone (or formed during ozona- decomposition, such as 0H~, transition metal ions, hydrogen peroxide, superoxide, etc. (Figure 2) . Also, most common water impurities such as bicarbonate, carbonate, and organic material react with OH radicals and act as scavengers, and some react with molecular ozone. Thus, the relative importance of direct vs. radical reactions must be determined experimentally for each source water. Table 1 is a summary of pseudo first order rate constants for the ozone runs performed on groundwater samples from the North Hollywood Well No. 26 spiked with 500 and 50 ug L"1 of TCE and PCE respectively. The initial alkalinity of the source water is 200 wg/L (as CaC03) and the TOC value is 1.1 lag/L. Figure 3 is a plot of typical runs for TCE, showing the pseudo first order nature of the process. It is interesting to note that increasing pH from 4 to 10 has little effect on the destruction of TCE as shown by the data in Table 1. This may be due to the important role played by the bicarbonate positive and oxidation. ion in negative the water, which effects on the can have both rate of substrate Bicarbonate and carbonate ions react with OH by electron transfer reactions (10) and (11) shown in Table 2. 9 Since the rate constant of OH radicals reacting with carbonate ions is far greater than that with bicarbonate ions, increasing the pH of the medium will be expected to decrease the efficiency of OH trapping by TCE or PCE. On the other hand, increasing pH values will accelerate the decomposition process which produces more hydroxyl radicals (Figure 2 and equation 6). Apparently, the competing effects noted above essentially cancel each other and their is no practical advantage to increasing the pH when TCE destruction is the desired result. It should be noted, however, that this conclusion may not apply to all substrates and test waters, especially those which are low in alkalinity and higher in natural promoting agents. 0zone/H2Q2 System. According to the works of Hoigne et al (15-17) and'Hart et al (18-19), hydrogen peroxide can initiate the decomposition of ozone by a single electron transfer process wherein the initiating species is the hydroperoxide ion H0 2 ~ (reaction 1, Table 2). The products of this reaction are the ozonide ion 0 3 ~ and the hydroperoxide radical HO2, each of which can form OH radicals by the pathways shown in Table 2. constants for equations (1) and 10 From the rate (6) it can be shown that initiation by peroxide is much faster than by hydroxide ion when the former is present in the millimolar range (15). Using a steady state approximation for the various intermediates shown in Table 2 the following equation for the steady state concentration of OH may be derived: [OH] = 2k lKPER [H2023r033/rH+] + *MM k (13) s % it i3 where the constants are defined in Table 2, M is the substrate (TCE or PCE), and S^ refers to the various substances in the water which act as scavengers of OH radicals. The "2" in equation (13) symbolizes the fact that two OH radicals are formed from each initiation step (equation 1) , one from the 0 3 ~ ion and one from the H0 2 radical. The rate of TCE or PCE oxidation is given by the expression -d(ln M)/dt where k M 0H = k0 = k M/OH [OH] + k M f 0 3 [0 3 ] f (14) and kjj Q 3 refer to rate constants for reaction of the substrate with OH radicals and ozone respectively, and k 0 is the observed pseudo first order rate constant for overall oxidation of M. Under conditions where the direct reaction of M with 0 3 is negligible, the last equation may be combined with equation (13) to yield equation (15): 11 = ko k M,OH2klKpER [H2Q23[033/[H+3 k MtM] (15) +^ki[Si] As In hard ground water the principal scavengers S^ will be bicarbonate ions that are present in relatively high concentration compared to the pollutant substrate M; then equation (15) will reduce to equation (16): k0 Equation (16) = k states Mf0H2*lKpER [H202 3CO3 3/[H+] k HC03tHC03~3 that the psuedo first-order (16) rate constant for the OH radical oxidation of a substrate in the O3/H2O2 process should be proportional to the liquid phase concentrations of ozone and peroxide, and inversely proportional to bicarbonate and hydrogen ion concentrations. In a CSTR, the level of ozone present in solution [03] is determined by the rate of transfer from the gas to the liquid phase minus the ozone lost to decomposition and reaction: {d[03]/dt)t = k1*a{P/H - [03]) - £> kj[Sj][03] (17) \ where -£ Sj refers to all of the species that consume ozone, k^*a is the overall mass transfer coefficient, P is the partial pressure of ozone in the gas phase and H is the1 Henry's Law constant for ozone in water (82 atm-L-inole-1) . 12 If we assume that the major reactions consuming ozone are equations 1 and 2 (Table 2), then equation (17) reduces to equation (18) : = k!*a{P/H - [03]> - 2k 1 Kp ER [H 2 0 2 ][0 3 ]/[H + ] (18) (d[03]/dt}t When the rate of transfer has reached a steady state, the ozone concentration in the liquid phase is given by equation (19), obtained by setting equation (18) to zero: [03] - *l*a(P/H) + 2k 1 K PER [H 2 0 2 ]/fH T ] *l*a (19) This expression for residual ozone can then be plugged into equation (16) to give equation (20): = kMyOH2kiKpER[H202]/[H->-] ^ k!*a(P/H) (20) *-o ^HC03[HC03-] kx*a + 2k 1 K pER [H 2 0 2 ]/[H + ] k When the reaction 2kiKPER[H202]/[H+] conditions is iauch are such that greater than ki*a, peroxide levels are high, then equation the term as when (20) reduces to equation (21): k0 = ^M>0H)(ki*a)(P/H) k (21) HC03[HC03~3 that is, the value of k 0 will be proportonal to the mass transfer coefficient, the partial pressure of\ozone in the gas phase and the rate constant for reaction of\OH radicals with the substrate M. When peroxide levels are low, equation 13 (20) reduces to equation (22) : k0 = *MfOH2*lKpER[H2023/[H+3 (P/H) k HC03tHC03-] (22) which states that k 0 should be a linear function of peroxide dose. In both cases, k 0 will be inversely proportional to bicarbonate levels, the assumed principal scavenger. The experimental data in Figures 4 and 5 show that hydrogen peroxide has a significant accelerating effect on the rate of oxidation of TCE and PCE. for the oxidation of TCE Pseudo-first order rate constants and PCE at various ozone and peroxide dose rates are shown in Table 3. In Figure 6 the values of the rate constants at an ozone dose of 15 lag/min are plotted versus the ratio of peroxide to ozone dose. The shape of the curve is precisely that which is predicted by equation (20) as discussed above.1 The data in Table 3 show that the addition of hydrogen peroxide causes a maximum rate enhancement for TCE 'oxidation by a factor of about 1.8 to 2.8, depending on the ozone dose rate. PCE rates are enhanced much more dramatically, from 1 There is another possible explanation of the shape of Figure 6, namely, that superoxide^ 0 2 ~ does not enter into subsequent OH formation by equation (5), i.e. in excess concentration hydrogen peroxide quenches OH radicals by equations 7 and 8 without contributing to the pool of OH precursors (4). There is little reason to suspect that this is the case but it is a possibility that cannot be discarded. 14 2.0 to 6.5 fold. This is apparently due to the fact PCE reacts primarily by a radical mechanism whereas TCE reacts both by direct mechanism.2 reaction with 03 and by the radical When OH radical chemistry is dominant, the ratio of the rate constants for TCE and PCE oxidation should be equal to the ratio of their rate constants with OH radicals: k o,TCE/ko,PCE = k 5a/ k 5b = 1 '7 <23) Inspection of Table 3 will show that the ratio of psuedo first order rate constants is close to this value when the ratio of H202 to O3 is near unity and when the ozone dose rate is relatively low (4.5 mg/min). Effects of Bicarbonate on O3 end O3/H2O2 oxidal'.ions. There is a significant amount of bicarbonate in the ground water tested, which should trap OH radicals and interfere 2 The ratio of the pseudo first order rates constants o TCE/ko PCE wner> n o peroxide was added are not constant (Table 3)'. This is probably due to the fact that pure 0 3 chemistry is never observed in a natural water, and especially at low ozone doses there is a mixture of direct O3 and OH radical chemistry. Only when there are no natural promoters \can the ratio approach the value for the direct reaction, which according to Hoigne and Bader should be greater than 170 (13) . Since the ratio for reaction with OH radicals is\ only 1.7 the observed values with no added peroxide are (evidence of mixed chemistry. k 15 with the destruction of target compounds such as TCE and PCE. The OH radical is far more reactive with TCE than with the bicarbonate ion, as shown in Table 2; however, the molarity of the bicarbonate ion (6.0 x 10~ 3 M at 300 mg/L as CaC03) is much greater than that of the organic halides (TCE = 0.76 x 10" 6 M at 100 ppb). The rate constants for reaction of TCE, PCE and bicarbonate with OH radicals can be used as a basis to predict the efficiency Q of radical quenching by TCE and PCE, defined as the percentage of OH radicals that are quenched by TCE or PCE respectively. Assuming bicarbonate is the principal quenching agent, Q may be approximated by equation (24): Q = k 5a[ TCE] x k5a[TCE] + k10[HC03-] 10Q _ * 5a [TCE] x k10[HCO3-] 100 (24) Batch scale runs to test the effect of bicarbonate softening of Los Angeles ground water were not conducted in this study (however, see the following paper). bonate is well illustrated, The effect of bicar- however, in the experimental data shown in Figure 7 and Table 4. Arrowhead distilled water, ( [HC03~] < 0.1 mM) was used as the source of water for this set of runs. Sodium bicarbonate was used to adjust the bicarbonate level and pH was adjusted by addition of sodium phosphate buffer solution. constants from alkalinity. these runs as a Table 4 summarizes rate function of bicarbonate Several features of this data are interesting. 16 I First, as ;shown in Figure 7, the rate of TCE oxidation is so fast in this water at low bicarbonate levels that TCE is degraded from 500 ppb to 3 ppb within 10 minutes. Under these conditions it is difficult to obtain good rate data with our experimental system. ^o TCE/^O PCE are Second, values of * n t-ne range predicted from equation (23) for OH radical reactions. Third, the rate constants at low alkalinity values are a factor of two to three greater than those observed at similar ozone:peroxide doses in the natural groundwater. This is apparently due to the fact that there are other radical scavengers in natural waters that decrease the efficiency of the oxidation of the olefins. Fourth, the value of the product of k 0 times the molar bicarbonate level is a constant at a given ozone dose rate, as predicted by equation (21). Finally, the values of the efficiency factor Q show that at the high alkalinity values of North Hollywood ground water, TCE and PCE are not using more than a few percent of the available OH radicals. the expected effect of bicarbonate These results verify ion and suggest that softening prior to oxidation may be a cost effective addition to the 03/H202 process under some conditions. Oxidant Doses for 95% Rercoval of Substrates The rate constants in Tables 1 and 3 may be used to calculate the dose of ozone required for 95% destruction of 17 the two olefins (Table 5). A detailed analysis of this data will not be given here; however, it is clear that the results suggest that the process is quite promising. Further details of cost/effectiveness of the process are given in the following paper. Evidence for Enhancement of Ozone Ilass Transfer When liquid phase reaction rates are high, the mass transfer coefficient k^*a may without rapid reaction k^a. be larger than the value The enchancement factor E is defined as the ratio k^*a/k^a. Direct measurements of k^a in the CSTR used in this work give a value of k^a of 4.6 (±0.4)x 10~ 4 s - 1 . These runs were made in water from North Hollywood Well No. 14 at three different ozone doses with no peroxide added (Figure 8 ) . When peroxide levels are high there is essentially no residual ozone found in the liquid phase or in the ozone offgas. For example, in a run with ozone dose at 14.9 mg-min"-1- and peroxide dose at 10 mg-min-1, the residual ozone levels \ were near our detection limit for the indigo method (0.1 mgL-1V. That is, all of the ozone added is consumed (>98%). Hence\ we may may assume that [03] << practical purposes, d[03]/dt is zero. 18 P/H and for all Equation (25) may then be used to calculate a lower limit value for k^ a: . * Ozone doseCmole-L-1-^"1)• Ozone utilization (0.98) P (atm)/ H (atm-L-raole"1) (25) The value calculated from equation (25) is k^*a = 7.8 x 10~ 4 s_1. Thus, the mass transfer enhancement factor for these conditions is at least a factor 1.7. CONCLUSION Direct ozonation of TCE and PCE in a high alkalinity ground water is a relatively slow process and little effect is seen when the pH is increased from 4 to 10. hydrogen peroxide up to a H202/03 The addition of ratio of about 0.5-0.7 (w/w) accelerates the oxidation of TCE by a factor of two to three tiroes and PCE from two to six times, depending on the ozone dose. Because of an apparent mass transfer effect, increasing the hydrogen peroxide dose rate beyond a certain level does not increase the oxidation rate of TCE and PCE., however, at higher ozone dose rates further rate enhancemnts can be expected. Relative rate data for TCE vs. PCE oxida- tion suggests that the principal species involved in the oxidation is the OH radical. Processes that utilize hydroxyl radicals\to remove water contaminants are less efficient in high alkalinity water because of the presence of radical scavengers cuch as HC03~ end C03~2. 19 In the present case, the data suggest that TCE and PCE oxidation is still a promising process even though only a small percentage radicals are used for TCE/PCE oxidation. of the OH Water softening may therefore be used to further increase the effectiveness of the process. Acknovledqements This work was supported by the city of Los Angeles Department of Water and Power and the USEPA through CR813188, R. Miltner Project Officer. been subjected to review by EPA. This article has not Therefore, it does not necessarily reflect the views of the agency, and no official endorsement should be inferred. The authors are grateful to Marco Aieta, Rhodes Trussell and Carol Tate of James M. Montgomery, Consulting Engineers and to Larry KcReynolds of LADV7P for helpful discussions. \ 20 REFERENCES 1. Federal R e g i s t e r . (1987). 2. Glaze, W.H., "Drinking-Water Treatment With Ozone," Environmental Science & Technology, Volume 21, No. 3, pp. 224-230, 1987. 3. Glaze, W.H., J.W. Kang, and E.M. Aieta, "Ozone-Hydrogen Peroxide Systems for Control of Organics in Municipal Water Supplies," in The Role of Ozone In Water and Wastewater Treatment, Proceedings of- the Second International Conference, Edmonton, Alberta, p. 233 (28-29 April 1987). 4. Glaze, W.H., J.W. Kang, and D.H. Chapin, "The Chemistry of Water Treatment Processes Involving Ozone, Hydrogen Peroxide and Ultraviolet Radiation", Ozone: Science & Engineering, 1987 (in press). 5. Farhataziz and A.B. Ross., "Selective Specific Rates of Reactions of Transients in Water and Aqueous Solutions. P III. Hydroxyl Radical and Perhydroxyl Radical and Their Radical Ions", Natl. Stand. Ref. Data Ser.(U.S. Natl. Bur. Stand.) No 59 (1977). 6. (following paper) 7. Yocum, E.H.,"Ozone Mass Transfer in Stirred Vessels," Proceedings, 86th National Meeting, American Institute of Chemical Engineers, April 1-5 (1979). 8. Flamm, D.L., "Analysis of Ozone at Low Concentrations With Boric Acid Buffered KI," Environ. Sci. & 'Technol., 11:10:978 (October 1977). 9. Bader, H., and J. Hoigne, "Determination of Ozone in Water by the Indigo Method: A Submitted Standard Method," Ozone Sci. & Engng., 4:169 (1982). 10. Masschelein, W., M. Denis and R. Ledent, "Spectrophotometric determination of Residual Hydrogen Peroxide," Water & Sewage Works, pp. 69-72, August 1977. 11. Lazrus, A.L. , G.L. Kok, S.N. Gitlin, J.A. Lind, and S.E. Mclaren, "Automated Fluorometric Method for Hydrogen Peroxide in Atmospheric Precipitation", Anal. Chem. 57:917922 (1985). 21 12. Association of Official Analytical Chemists, Official Methods of Analysis, W. Horwitz, editor, p. 545 (1980). 13. Hoignd, J. and H. Bader, "Rate Constants of Reactions of Ozone With Organic and Inorganic Compounds in Water, I - NonDissociating Organic Compounds," Water Research, 17:173 (1983). 14. Staehelin, J., and J. Hoigne, "Decomposition of Ozone in the Presence of Organic Solutes Acting as Promoters and Inhibiters of Radical Chain Reactions," Environ. Sci. & Technol., 19:1206 (1985). 15. Staehelin, J., and J. Hoigne, "Decomposition of Ozone in Water: Rate of Initiation by Hydroxide Ion and Hydrogen Peroxide," Environ. Sci. & Technol., 16:676 (1982). 16. Buhler, R.E., J. Staehelin, and J. Hoigne, "Ozone Decomposition in Water Studied by Pulse Radiolysis. 1. H0 2 / 0 2 and HO3/O3 as Intermediates," J. Phys. Chem., 88:2560 (1984) . 17. Staehelin, J., R.E. Buhler, and J. Hoigne, "Ozone Decomposition in Water Studied by Pulse Radiolysis. 2. OH and HO 4 as Chain Intermediates," J. Phys. Chem., 88:5999 (1984). 18. Forni, L., D. Bahnemann, and E.J. Hart, "Mechanism of the Hydroxide Ion Initiated Decomposition of Ozone in Aqueous Solution," J. Phys. Chem., 86:255 (1982). 19. Sehested, K., J. Holoman, E. Bjergbakke, and E.J. Hart, "Ultraviolet Spectrum and Decay of the Ozonide Ion Radical, 0 3 , in Strong Alkaline Solution," J. Phys. Chem., 86:2066 (1982) . 20. Christensen, H.S., K. Sehested and H. Corfitzan, "Reaction of Hydroxyl Radicals with Hydrogen Peroxide at Ambient and Elevated Temperatures", J. Phys. Chem.', 86:1588 (1982) . \ 22 LEGEND OF FIGURES Figure 1. System. Schematic Diagram of 03/H202/UV Experimental Figure 2. Scheme showing the principle species in the decomposition of ozone initiated by hydroxide ions and OH radical quenching by scavengers. Figure 3. Effect of pH on the ozonation of TCE in North Hollywood well water. Ozone dose: 15 mg/min; Bicarbonate alkalinity: 200 mg/L as CaC03. Figure 4. Pseudo first-order plot for destruction of TCE by °3/H2°2 Process in North Hollywood well water. Ozone dose: 14.9 mg/min; Bicarbonate alkalinity: 300 mg/L as CaC0 3 ; pH: 7.2-7.4. Figure 5. Pseudo first-order plot for destruction of PCE by °3/H2°2 process in North Hollywood well water. Ozone dose: 14.9 mg/min; Bicarbonate alkalinity: 300 mg/L as CaC0 3 ; pH: 7.2-7.4. Figure 6. Effect of hydrogen peroxide on the pseudo firstorder rate constants of oxidation of TCE in North Hollywood well v:ater. Figure 7. Effect of bicarbonate on the 03/H202 process for destruction of TCE in Arrowhead distilled water. Ozone dose: 4.5 mg/min, H2O2 dose: 2.0 mg/min. Figure 8. Transfer of ozone into the CSTR with 'water from North Hollywood well No. 14. No added peroxide. 23 H •• _* CO 1 5-W •• a> »< a> •< •• •n -n o 7s •• ttame < © TO CO < 7; CO Sam Vent Ther in cr cr <o T>_ © tj 3 < D o N O a CO a. o c CO CO © © o H at fou o —*• 3 -* ?r 33 CO H c 01 C < 1/ 3 Wei o -n o CQ CD 3 2 •u © CO V) c © 33 © en ula tor a o Q> par ger 3 C to TJ 3 (on ewin o o 3 © o j~7; eroxide Feed Pump < *X3 s TJ >ne Kill Unit •-* O ^. o o N 3 33 .- -» fi> o 8H r-* <D 3 Hyd Val < a> ««> nder Val 23 r> o Oxyg en 5= Checl Vah CO 3 3 Q. © O fit a» o o r-» O; Electron Transfer Agents (EH) ( E n*1) Radical Quenchings (HCO3-, CO3-2,...) Substrate Oxidation (TCE.PCE) P^ 4. -2.0 10 15 Time (min) , : > - In Time (mfn) +•& InfESLJ LPCEj -1.0 ma HjO^mg o3 o 0.00 © 0.48 A 0.66 A 1.00 10 Time (min) 15 20 y ^0 0*2 S8|OOJ/^O^H B O|OUJ vo 8*1 £Q B U J / Z O Z H BUJ O'O H CO o c o I I o o -1 50 a o o to Q 3 o O a o -1.0-- ,n 3 Bl]- -°--5.0 -6.0 10 Time 15 (min) #31 kOG k L a DETERMINATION 2.000 O3 Dose ( m g / m i n ) o : 15 a : 8.5 A : 4.5 I X \ DL -1.000 0 5 10 15 20 Time (min) 25 30 35 40 TABLE 1 Pseudo-First Order Rate Constants for the 03/pH System NORTH HOLLYWOOD WELL NO. 26 Rate Constants x 10 4 (s_1) pH pH = 8 O3 Dose pH = 4 mg/min 4.5 8.4 15.1 TCE PCE TCE 5.0 7.8 11.0 2.8 3.0 2.3 5.0 8.4 12.1 24 pH = 10 PCE 2.4 3.1 3.0 TCE 6.1 9.2 11.4 PCE 3.4 4.6 4.5 TABLE 2 PRINCIPAL REACTIONS IN THE 0 3 / H 2 0 2 PROCESS REACTION CONSTANT REFERENCE H 2 ° 2 ^ H°2" + H* K P E R =1.6X10~ 1 2 M H 0 2 ~ + 03-»»03~ + H 0 2 k 1 =2.8xl0 6 M" 1 S~ 1 (15) H 0 2 ^ H+ + 0 2 " K HO2 =1.6xl0~ 5 M (15) 2. 0 2 ~ + 0 3 —»-03~ + 0 2 k 2 »1.6xl0 9 M" 1 S~ 1 (16) 3. 0 3 ~ + H"t-»-H03 K 3 =6.3xlO" 9 M (16) 4. H0 3 -*OH + 0 2 k 4 =l.lxl0 5 S" 1 (16) 5a. OH + TCE—9-Products (?) ksa^.OxlO^"^"1 (5) 5b. OH + PCE — > k5b=2 - 3xio9n~1s'~1 (5) (18) 1. •• 6. OH" + 0 3 - K ) 2 ~ + H 0 2 k 6 =70M~ 1 S" 1 7. OH + H0 2 ~—->0H" + H 0 2 lHy-7 .SxlO^'^-S"1 (20) 8. OH + H 2 0 2 ~~>H 2 0 + H 0 2 k 8 =2.7xl0 7 M" 1 S~ 1 (20) 9. OH + 10. OH + HC03=-»-OH" + HC0 3 k 1 0 =l. Sxio^'^-S" 1 (5) 11. OH + C 0 3 ~ > O H ~ + C 0 3 = k 2 1 =4.2xl0 8 M~ 1 S~ 1 (5) 12. HC0 3 ~—> H+ + C 0 3 = K Sj^—>Products (?) HCO3=5.0xl0"l 1 M ^Cs^ is the S U M of the various matrix substrates that quench hydroxy1 radicals. 25 TABLE 3 Pseudo-First Order Rate Constants for the O3/H2O2 System NORTH HOLLYWOOD WELL NO. 14 Rate Constants x 1 0 4 (s O3 Dose: 4.6 mg/min mg H 2 02/mg O3 0.00 0.11 0.33 0.54 1.00 k0 TCE PCE TCE/PCE 4.1 5.0 8.8 8.1 7.0 1.9 2.2 4.4 4.1 4.0 2.2 2.3 2.0 2.0 1.8 TCE PCE TCE/PCE 7.2 10 16 18 20 2 4 4, 1 7, 1 8, 7 7.3 TCE PCE 11 14 20 27 29 30 27 1. 2. 7, 7. 8. 7. 9.0 O3 Dose: 8.4 rag/rain mg H20 2 /mg 0 3 0.00 0.12 0.36 0.60 1.00 3.0 2.4 2.7 2.1 2.7 O3 Dose: 14.9 mg/min mg H20 2 /mg O3 0.00 0.07 0.14 0.48 0.67 1.00 1.34 26 TCE/PCE 7.9 5.4 2.8 3.6 3.2 3.9 3.0 TABLE 4 Effect of Bicarbonate on the Rate of Oxidation of TCE and PCE with the 0 3 /H 2 0 2 System1 H [HC03""] (mM) 2°2 : 1 0 mg/mi-n 0 3 : 15 mg/min H2O2: 2 mg/min O3: 4.5 mg/min 3 1 *o X 10 S"" TCE PCE ko X 10 3 S-l TCE/PCE TCE PCE TCE/PCE >11.1 —— >8.4 >6.8 — 5.9 1.8 3.5 2.0 1.9 QTCE 1 0.0 >16.3 2.0 11.4 3.6 6.5 3.7 1.8 2.0 1.1 1.8 6 5.2 5.2 2.7 1.9 1.5 0.8 1.4 4 1 10 Q: Efficiency of TCE of OH radicals based on equation (24); calculated at a concentration of TCE of 100 ppb and at lower of two dose rates shown above. 27 1 TABLE 5 Dose Required for 95 % Removal of TCE and PCE North Hollywood Well No. 26 Process « 0 3 (mg/L) H 2 0 2 (mg/L) TCE PCE TCE O3 1 9 33 - 0 3 /H 2 0 2 2 4 12 2 PCE 8 1 Conditions: : 0 3 Dose: 15 ug/min, pH: 8.0; 2 : O3 Dose: 15 mg/inin, H 2 0 2 Dose: 10 mg/mi 1-2 : Initial TCE and PCE concentrations: and 50 ppb; Alkalinity: 200 iag/L as CaC03. 28 IHACTIVAIIOH ALD/OR DESTRUCTION!cy ... OF THK CYSTS OF GIARDIA WITH PROTOZOHK mmi-mCharles P. Hibler, Department of Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80523 December 19, 1984 IHXR0DUCTION: At the request of Dr. Robert McGregor, Water Management, Inc., 1660 South Albion Street, Suite 513, Denver, Colorado 80222, we performed seven static tests to determine if photozone was effective in the inactivation and/or destruction of the cysts of Giardia duodenalis of human origin. Water Management, Inc., is investigating the potential effectiveness of photozone equipment at an established water treatment plant at Aspen, Colorado, as an additional safeguard against Giardia. The existing plant is a rapid sand filtration with chemical flocculation and coagulation followed by chlorination in sufficient quantity to provide the required amount of free chlorine throughout the distribution system. Photozone will be introduced as an added safeguard and as an application that possibly will be more effective in inactivation and/or destruction of Giardia cysts. Therefore, Water Management, Inc., wanted to determine if photozone together with a small amount of free chlorine was effective. 1 The time of year when this system possibly would be at risk for Giardia would be in the fall and winter months when temperatures are between 0-5°C and turbidity readings are in the range of 0.5-0.8 NTU. The static test was designed to approximate these conditions 4s near as possible in Trials I - III on October 24,; 1984yy Based, "on .ft-he /results* ;ofj these 'tests, :^additio*nal|J conducted on November 7-8, 1984, to confirm the results of the first tests and to ,|tT^;: :, determine if there would be any reductions in the effectiveness of the photozone at higher levels of turbidity. TRIALS I - III Materials and Methods: Location: The Poudre River at Fort Collins Water Treatment Plant tl was chosen as the site for this test because water temperatures this time of year range between 0-4°C, turbidity is between 0.5-0.7 NTU and the laboratory at the Water Treatment Plant has sufficient equipment for measuring the temperature, turbidity, and free chlorine; moreover, the plant is a source of power for the equipment necessary. Methods; For the purpose of this series of static tests, a 55-gallon nalgene tank was positioned near the Poudre River and filled with raw Poudre River water. Temperature, turbidity, free chlorine, and photozone levels were established by representatives of Water Management, Inc. Source of Photozone: \ The\ photozone was generated by a ultraviolet tube through which ambient air concentrated with oxygen was passed. The oxygen concentration of the concentrated air supply was estimated to be 28 percent by weight compared to 23 percent by w.iight for_ normal air. The purpose of the oxygen concentrator in the tests was to enhance the overall production of photozone to reduce the setup time for each test. The photozone was then passed into the nalgene drum and circulated by means of a perforated PVC tube coiled at the bottom of the drum. Free photozone was monitored by the oxidation/reduction potential (ORP) expressed in millivolts. For all the tests, the level of photozone was maintained between 0.3 and 0.6 mg/1. • - -•••-.::?.' Source of Giardia duodenal is ' C Y S ^ S S X ^ : ^ : , , :..j-;!:.;;];;.;..;'lj? \ 'X"-.;-;/ Cysts were obtained in a human stool specimen through the courtesy of a local hospital. Cysts were diluted in distilled water, strained through several layers of gauze to remove the larger material and maintained at 5°C in distilled water. Counting of the cysts was performed by direct microscopic examination of 50 microliter subsamples (four replicate counts) and then extrapolated to determine cysts/mililiter and subsequently cysts/sample. This technique provides a reason- able level of accuracy but is not an absolute figure. This source wa6 determined to have a total of 6.5 X 1 0 6 cysts/ml. Although the morphologic quality of these cysts was superb, morphologic quality does not necessarily mean that the cysts were alive/or infectious. This can only be determined by a laboratory excystation procedure or the introduction of these cysts into a suitable biologic model. Our laboratory uses the Mongolian gerbil (Meriones unguiculatus) to determine infectivity. The standard procedure is to introduce 5,000 cysts per animal into each of five Mongolian g e r b i l s aged 7-8 weeks. If these cysts are highly infectious, the gerbils will begin producing cysts as a result of the infection on day four post inoculation. They will continue to produce cysts for the next 4-5 days reaching a peak cyst productivity on Day 6 to 7 post inoculation. If the sample is highly infectious, the total \ fecal output of five Mongolian gerbils over a peiiod of 24 hours should produce between 20 and 30 million cysts. Infection 3 of five Mongolian gerbils with the cysts from this human source resulted in a cyst production 7 days later of 27.3 x 10" Giardia cysts. The cysts from these gerbils were thoroughly cleaned as given above, diluted in distilled water, counted as closely as possible, and maintained in distilled water until the time of the trial (two days later). PROTOCOL: 'r*^&;Jneprotocol established was to run a .series of threestati'c tests 'maintaining^-?.^'-: a temperature of 0-4°C, a turbidity of 0.5-0.8 NTU, a constant amount of photozone, .; ••, and a varying amount of free chlorine at each trial. During each trial, 6ubsamples containing Giardia cysts were to be withdrawn and the chlorine and photozone denatured with the addition of IX sodium thiosulfate. 30-minute treatment subsample and a 120-minute treatment subsample. The Giardia cysts contained in and Each trial called for a these subsamples were to be examined for morphologic quality then introduced orally into susceptable Mongolian gerbils to determine if they were inactivated and/or destroyed. For each trial, once the free photozone and the free chlorine and other parameters had been established, a total of 5.13 x 10-* Giardia cysts were introduced into the nalgene drum (10,000 per gallon). At 30 minutes post exposure a 15-gallon sample was withdrawn from the drum with the aid of a small centrifugal ^ P pump and the suspended material trapped on a one micron (nominal rating) polypropylene filter. As the subsample was being extracted, sodium thiosulfate was trickle-dosed into the line. This same procedure was repeated for the 120-minute trial. Filters containing Giardia cysts and other material present in the raw water were refrigerated, taken to the laboratory, and processed in distilled \ water. Processing a polypropylene filter calls for cutting the fibers away from \ the core and hand washing in distilled water. Once all the filters had been processed, they were refrigerated at 5°C until the following morning when they were processed for animal inoculation. Distilled vater in gallon jars containing Giardia cysts and other material were concentrated by centrifugation until the contents of the filter had been concentrated into a 10 milliliter volume. SubsampleB of this material were then examined for Giardia cysts to determine morphologic quality and to calculate the total numbers for animal inoculation. •?;;•£ .The protocol called for the inoculation of 7-10 Mongolian gerbils with;! •' Giardia cysts from each trial. A group of 7-10 Mongolian gerbils were to be inoculated with cysts from the source material to determine infectivity. comparable number of negative controls was also included. A In addition, a group of 7-10 gerbils were to be orally inoculated with cysts that had been maintained in river water during the trial and exposed to 1% sodium thiosulfate. RESULTS: Five days post-exposure the Mongolian gerbils infected with the source material (positive controls) passed 35 x 10& Giardia cy6ts in a 24-hour period. The Mongolian gerbils infected with the river water control passed a total of 32 x 10° Giardia cysts in a 24-hour period. The Giardia source material and the Giardia cysts exposed to river water were rated morphologically superb (microscopic examination) the day following the trials and for one week thereafter (following which they were not further examined). However, in each photozone trial only a few Giardia cysts could be found following 30 minutes- exposure to the combination of ozone and free chlorine; at 120 minutes exposure to free chlorine no Giardia cysts could be found. Therefore, no Mongolian gerbils were inoculated with any of the material. DISCUSSION: The discovery that only a few Giardia cysts vere present in the 30 ninute post-exposure subsamples was surprising. Even more surprising was the obviouB fact 5 that these cysts were dead. The internal structures were shrunken and shriveled to the degree that they were unrecognizable as cystB. Re-examination of the protocol used indicates that the combination of photozone and free chlorine killed the cysts before the 30-minute contact time. Even though the photozone and free chlorine were denatured immediately with the addition of 1Z sodium thiosulfate, apparently.' the deterioration process continued while the.jcysts werec refrigerated in distilled vater overnight, thus destroying or rendering unrecognizable the cysts that were present. It has been established, and it is our experience, that the amount of free chlorine alone in this system (0.21 to 0.58 mg/1) is inadequate to kill the cysts in 30 minutes at 0-4°C, much less to effect cyst destruction. Moreover, the examination of Giardia cysts exposed to this amount of free chlorine reveals that the morphologic quality of cysts can be maintained at 5°C for at least three and usually four days before the internal structures become distorted and the cysts become unrecognizable. In addition to an almost complete destruction of all Giardia cysts present in this raw water, the crustaceans, free-living nematodes, nematode eggs, and crustacean eggs found normally in this raw water (and present in the river water control) were not present in these trial samples. RECOKHKL'MTIOHS: The combination of photozone and free chlorine, together with the'holding time post treatment obviously effected total destruction of the Giardia cysts. It was recommended that a subsequent series of trials be initiated and subsamples withdrawn for morphologic analysis and animal inoculation at 5, 10, 20, and 30-minute intervals. It was further recommended that these samples be processed as soon as possible after the photozone and the chlorine had been denatured. Cyst deterioration to the point of complete destruction obviously even 6 continued though the photozone and chlorine have been denatured. It was further recommended that the subsequent trials be performed using only photozone and not a combination of photozone and chlorine to determine the effect of ozone alone on cyst inacti- vation and/or destruction. It was also recommended that further tests be conducted at higher turbidity levels to determine any interferences with photozone. 'f-'^r-l/. These^ jrecommendations vere^carried out in.Trials IV - VII on November .7-8,..'••,.' 1984. ':;-;•••i--..0-::-. .- ./'[-• :•.:•'. • " ' ; -• •' • • TRIALS IV - VII Introduction; The results of Trials I through III indicated that 0.21 - 0.58 mg/l free chlorine in combination with 0.3 - 0.6 mg/l of photozone not only inactivated and/or killed Giardia cysts but also completely destroyed the great majority. However, the procedure used in Trials I through III necessitated holding the cysts overnight in a refrigerator at 5°C before animal inoculation. The following morning very few cysts could be found in the 30-minute contact time trials while none could be found in the 120-minute contact time trials. Even though the activity of the chlorine and the photozone was stopped by the addition of 1% sodium thiosulphate, we felt that cyst deterioration continued despite the inactivation of the photozone and the free chlorine. Therefore, at the request of this investigator a second series of trials was initiated. In general, the subsequent trials called for contact times with photozone and free chlorine of 5 minutes, 10 minutes, 20 minutes, 30 minutes, and one hour. These were done, in part, to determine if there wa6 any physical deterioration of the cysts as a result of exposure to photozone and chlorine, and also to determine if the activity of photozone and chlorine in combination would inactivate and/or kill the cysts at an earlier time than 30 minutes. Previous investigators have shown that photozone 7 ' alone will inactivate and/or kill Giardia cysts as early as 5 minutes at 1 mg/1. However, these investigators were using distilled water, Giardia muris. and laboratory excystation of cysts as the indicator of inactivation or death. Tests were also conducted to determine the effectiveness of photozone without chlorine and at turbidity levels in the range of 2.6 - 4.6 NTU. A= series of four trials were planned. Trial IV would examine cysts for- morphology and animal inoculation at 5, 10, .20, 30, and 60 minutes using Poudre River water with a turbidity of 0.74 NTU, a temperature of 4.1°C, 0.3 - 0.6 mg/1 photozone and 0.21 mg/1 free chlorine. Trial V was designed to examine cysts for morphology and animal inoculation at 30 and 60 minutes using raw Poudre River water with the same level of photozone and no chlorine. Trial VI was designed to examine cysts morphologically and by animal inoculation using raw Poudre River water with the same level of photozone, no chlorine, and increasing the turbidity to 2.6 NTU with Bentonite. Trial VII was designed to examine the cysts morpho- logically and by animal inoculation after 30 and 60 minutes exposure to raw Poudre River water with the same level of photozone, no chlorine, and 4.6 NTU turbidity. A concerted effort was made to keep the lag time at a minimum (the period between inactivation of the photozone and the morphologic examination or inoculation of animals). Materials and Methods; , Location; The location of these tests and the conditions for these tests were the same as in Trials I through III. Methods : The methods of tais series of tests were the same as in Trials I through III. 8 Source of Photozone: The source of the photozone for these trials was the same as the source for the Trials I through III. Source of Giardia doudenalis cysts: The source of the cysts was the same as for Trials I "through III, and wa«*;;':.';,';; determined to have a total of 37.0 X 10 6 cysts/ml. These cysts were likewise • introduced into the Mongolian gerbil with essentially the same results as in Trials I through III. PROTOCOL; General: For trials IV, V, and VI the 55-gallon Nalgene drum was seeded with 2 million Giardia cysts (40,000 per gallon); for Trial VII an additional 2 million Giardia cysts were added, making a total of 4 million (80,000 per gallon) for that particular trial. Trial IV: For this trial, raw Poudre River water at a temperature of 4.1°C, turbidity 0.73, photozone 0.3 - 0.6 mg/1, and 0.21 mg/1 chlorine was used. Five minutes after introduction of the cysts a 1 gallon grab-sample was removed and sufficient sodium thiosulfate was added to provide a 1% solution. The same procedure was used at 10 minutes, 20 minutes, 30 minutes, and one hour. These one gallon grab-samples were siphoned through a 5 micron nucleopore membrane, the membrane washed with distilled water, and the resulting filtrate centrifuged for 5 minutes at 1500 rpm. Cysts were examined for morphologic quality and then \ introduced into five Mongolian gerbils at an estimated 5,000 cysts/animal. Trial V: Photozone was generated to maintain 0.3 - 0.6 mg/1. Raw Poudre River water at a temperature of 4.0°C and a turbidity of 0.75 NTU was used. At 30 minutes and 60 minutes post-exposure time 5 gallons of the suspension was 9 J pumped through a 1 micron polypropylene filter. This filter was cut to the core, processed in distilled water, and filtered through a 5 micron Nucleopore membrane. The filtrate washed off the nucleopore membrane was centrifuged for 5 minutes at 1500 rpm and the cysts were examined for morphologic quality and then inoculated into five Mongolian gerbils at an estimated 5,000 cysts/animal. Trial VI; Bentonite was added to . the Poudre River water to praise the turbidity to 2.6 NTU. Water temperature was 4.5°C and photozone was maintained at 0.3 - 0.6 mg/1. At 30 minutes and 60 minutes five gallon samples were pumped through a one micron polypropylene filter and the samples processed as above. Trial VII: For Trial VII, an additional 2 million Giardia cysts were added to the existing quantity of water, and an additional amount of Bentonite was added to raise the turbidity to 4.6 NTU. Water temperature was 4.6°C. Sufficient photozone was added to maintain a level of 0.3 to 0.6 mg/1. At 30 minutes and 60 minutes 5 gallon samples were pumped through a 1 micron polypropylene filter and the samples processed as given above. River Hater Control; Subsequent to the trials, a one gallon grab-sample of Poudre River water was inoculated with sufficient sodium thiosulfate to make a 1% solution and 25,000 Giardia cysts from the source material was added. The following morning the cysts exposed to sodium thiosulfate and the raw Poudre River water were inoculated into 5 Mongolian gerbils at a level of approximately 5,000 cysts per gerbil. An additional 5 Mongolian gerbils were inoculated with the source material used for the trial at about 5,000 cysts per gerbil. An additional 5 gerbils were maintained as uninoculated controls. RESULTS; The results are presented in Tables 1 and 2. The lag tine between inactiv- ation of the photozone and/or chlorine was 20-25 minutes for the 5 and 10 minute 10 samples in Trial IV; thereafter, lag time was cut to 15 minutes in the 20 minute, 30 minute, and 60 minute samples from Trial IV and all samples in Trials V, VI, and VII. The morphologic quality of cysts in Trial IV were judged excellent at 10, 15, and 20 minutes. 5, At 30 minutes post-exposure, fewer Giardia cysts could be found and these were of poor '.morphologic quality, indicating that they were dead. The same results were obtained at 60 minutes exposure; however, fewer- cysts could be found. In Trial V a considerable number of the Giardia cysts were judged morphologically excellent at 30 minutes exposure, but fewer cysts were present in this sample. At 60 minutes exposure, few cysts could be found and all of these were judged to be of poor morphologic quality. In Trials VI and VII all Giardia cysts found at both the 30 and 60 minute sampling periods were judged to be of excellent morphologic quality. DISCPSSIOH; The results of Trial IV indicate that the amount of photozone in combination with chlorine was effective in killing and/or rendering the cysts of Giardia inactive between 20 and 30 minutes postexposure. In Trial V, the chlorine was eliminated and, as a consequence, three of the five gerbils became infected with Giardia at 30 minutes post-exposure; however, one of these animals had a very light infection. This indicated that photozone alone killed the cysts at sometime between 30 and 60 minutes exposure. The use of photozone at tfyese levels, together with turbidities of 2.6 and 4.6 NTU did not kill many of the Giardia cysts in the absence of chlorine. The test results are reformatted in Table 3 to assist in an evaluation of alternative Giardia control design concepts. For a photozone concentration of 0.J - 0.6 mg/1, a free chlorine of 0.21 - 0.58 n.g/1, and a turbidity of 0.53\0.73 NTU, 30 minutes of treatment time are adequate for the deactivation of 11 \ Giardia cysts. If there i6 no free chlorine, and a turbidity of less than 0.70 NTU, a treatment time of 30 - 60 minutes is required. If shorter treatment times and no free chlorine .are desirable, additional photozone is required. If the turbidity exceeds 2.30 NTU, treatment times in excess of 60 minutes of additional photozone are required to control Giardia cysts. 12 Xi Xi 60 u 3 •r-4 .c oo 3 o > O t-i o 1-. 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Page 224, Mtrch 1987 Copyright © 1987 by the American Chemical Society and reprinted by permission of the copyright owner. Drinking-water treatment with ozone Ozone is a powerful disinfectant and oxidant, but its chemical byproducts need to be better understood 3 William H. Glaze University of California, Los Angeles Los Angeles, Calif. 90024 Ozone came into use as a drinking-water disinfectant as early as 1906 at the Bon Voyage plant in Nice, France; since then, more than 1000 facilities throughout Europe have adopted the practice (/). Some use ozone as the primary or sole disinfectant; others use it as an oxidant for the control of flora, odor, and color and to reduce the manganese and iron content of drinking water. Lately, engineers at European plants are finding that preozonation enhances the flocculation of suspended particles in surface waters, and its use for this purpose is expanding. The use of ozone in North America, however, has only recently begun to gain acceptance. According to Rice, the number of ozonation plants in the United States has increased from five in 1977 to 20 in 1984 (1). During the same period, the number of plants in Canada increased from 23 to nearly 50. Large plants arc beginning operations this year in Los Angeles and in Hackensack, N.J.; one plant is scheduled to open in Myrtle Beach, S.C., in 1988 (Table 1). The Los Angeles plant contains one of the largest ozone production facilities in the world. One major factor in the increased interest in ozone is the need to decrease the use of free chlorine in water treatment in keeping with legislated maximum contaminant levels (MCLs) for trihalomcthaoes (THM.s). For many years, free chlorine has been the disinfectant of choice in North America Chlorine is not only a disinfectant, it is a powerful oxidant Unfortunately, chlorine also produces byproducts, such as THMs, that can be harmful to human health. The need for THM control has forced water utilities to search for appropriate substitutes. Water treatment by chloramination (the combination of free chlorine and ammonia) has emerged as the most popular alternative disinfection process because chloramines do not form THMs. Chloramines are weak oxidants, however, so stronger oxidants, particularly ozone and chlorine dioxide, are being considered as substitutes for chlorine at the beginning and middle of the treatment process. Ozone is gaining in popularity for other reasons as well. In tests in which ozone has been compared with chlorine, ozone has been shnwt; to be superior to chlorine as a coagulant 1.2). It also appears to foim much smaller amounts of mutagens than cither chlorine or chlorine dioxide do (/f) In addi- tion, when ozone decomposes it generates radical intermediates that have much greater oxidizing power than ozone itself docs. The use of chemical oxidants to disinfect water is shown schematically in Figure 1 Ozone generation Because ozone is an unstable gas, it must be generated where it will be used. The most common technique for generating ozone is the cold plasma discharge method, in which ozone is formed by decomposition of diatomic oxygen: O. (corona discharge) O + O O. - o jiSil (). Ill <-') Figure 2 is a double tube n/one.gcn crating unit commonly found in largescale applications. Large-scale generators can contain as many as 400 double rubes, and they can generate 600 kg' day of ozone when dry oxygen is the feed gas. With air, the yield of ozone is about 50% of that generated with oxygen. In both cases the feed gas must be oil free and have a low. dew point ( - 5 2 °C to - 5 8 °C) Recent advances in ozone generation by the cold plasma FIGURE 1 Chanted oxidants In water treatment Sow oxidation by microorganisms, diatomic oxygen, and sunlight •-•:. c-tt*- •»-.-, Mid-point .'.-;£••'';".'."'•'•':.'.1'' oxidation: \ ' - " : : > ":-' Fostdisinfecttoo — Disinfection __ Protection of distribution system '— Control of btofouting Color removal, taste and odor : control, prevention of growth h basins, enhancement of cosguisdon snd tsdtrnenteliort, oxfctetfon of msngsnese, reduction of T H M formation potential Microbiotocfca) and photochsmical oxidation of natural organic materials, iron, and manganese - Nitrification of N H , ^m&- Stow ox&fclbn of menoareoe end n&iurcl organic mntsrtal • Typical points of application of oxidants in surface water treatment Environ. Sci Technol. Vol 21, No 3. 1987 225 method, which have been reviewed by Costc and Fiessinger (4), include the development of generators that operate in the medium frequency range (600 Hz); modifications in the design of the tubes, particularly the use of ceramic rather than glass dielectrics; and improved electronic systems for controlling current. Ozone also can be generated b> moans of ultraviolet (UV) light (less than 200 mm generated b> arc discharge lamps, in much the same manner as ozone is formed in the upper atmosphere (Equations 1 and 2). Although photochemical units cannot generate ozone at concentrations as high as those produced by cold plasma generators. UV generators may be competitive for small-scale systems because they require little capital investment and arc relatively easy to maintain. Transfer of ozone into water O/one produced by the cold plasma discharge method is present in air or oxygen at concentrations of 1-35? and 3-7 ft, respectively. These values correspond to 11-90 g ozone per standard cubic meter of air or oxygen. A number of devices have been used to transfer ozone into water; the most popular is the counter-current sparged column (Figure 3). Other systems include the stirrcd-tank reactor with diffuscr, methods that increase mass transfer through a combination of small bubble size and hydrostatic pressure, and the in-line static mixer. In the absence of chemical reactions, mass transfer from the gas phase to the aqueous phase can be described by Equation 3: tIC/Jt ••= k, a(C* - C) = k.afP/H - O (3) i/i which C is the concentration of • >/i'iii- in the liquid phase. ('* is the liquid-phase concentration in equilibrium 226 Environ Sci Technol. Vol 21. No 3.1907 with the concentration of ozone in the gas phase, P is the partial pressure of ozone in the gas phase, H is the Henry's law constant for ozone (0.082 aim m3 g-mol"1 at 25 °C), and kLa is the overall transfer coefficient. The upper curve in Figure 4 is a plot of ozone concentration in the aqueous phase in a static reactor as ozone containing gas is introduced. The initial slope of the line is related to k, a. which is assumed to be 0.36 g-mol m ' min ' in this case. Under actual conditions in a treatment plant, chemical reactions in the liquid phase consume ozone. Thus, Equation 3 must be modified to account for the loss of ozone by the following chemical pathways: dC/dt = k L a(/7H - C) M O ( H O - ) - ki(S,)(C) (4) Here, ko is the rate constant for the decomposition of ozone and the term on the extreme right is the sum of all the rate terms for chemical reactions that involve substrates (S,) in the water that consume ozone. The lower curve in Figure 4 is a plot of the mass transfer of ozone into the reactor. It takes into account only the middle term in Equation 4 (autodecomposition of ozone). A rate constant of 70 M ' s"' is assumed (5). Rapid reactions in the liquid phase will drive ozone dissolution; that is, the faster ozone is consumed in the liquid phase, the faster it will cross the gas-water boundary. This is likely to be significant to the design of reactors that arc based on the rapid decomposition of ozone into radicals. Drinking-water treatment Ozone as a disinfectant. Ozone suffers from two major limitations as an alternative to chlorine. First, it is unstable in water; it decomposes to oxygen at a rate proportional to the pH of the water. For example, at pH K. which is typical of many drinking-water sup plies, its haJf-lifc is less than one hour, too short to ensure that a residual disinfectant capacity will remain at the far reaches of a large distribution system. Despite its short lifetime, however, ozone is particularly effective against recalcitrant microorganisms. It is more effective than is chlorine for removal ol Giardia (an organism that causes a gastrointestinal disease), viruses, and certain forms of algae (6). Second, ozone reacts with natural organic substances to produce low-molecular-wcight oxygenated byproducts that generally are more biodegradable than their precursors are. These substances will promote biological growth in a distribution system ("regrowth"). further limiting the disinfection efficacy of ozone. For these reasons, ozone should be used in combination with other disinfectants that maintain an active residual for longer periods, and it should be combined with some method of filtration for removing biodegradable material. Ozone as an oxidant. Ozone can oxidize many nuisance compounds or potential toxicants in water supplies. These include natural color bodies, some compounds that produce unpleasant tastes or odors, manganese(ll) and iron(ll), and phenolic materials. Ozone also coagulates natural water constituents. For these reasons, ozone has been adopted as the preoxidant in the new Los\Angeles treatment facility, where pilot studies have shown that prcozonation substantially improves the filtration of.the raw water, thereby reducing the need"for other chemical coagulants and allowing shorter basin and filter contact times (2, 7). Comparison tests have shown that ozone is suhstantialh superior to chlorine for these purposes Although the mechanism of coagulation by ozone is not clear, several possibilities have been suggested. One possi- bility is. the oxidation of mcta] ions to yield insoluble forms such as Fe(III). Another is oxidation of humic material to form more polar or chelating groups, which induce coagulation. Finally, oxidative dissociation of natural organic material from colloidal clay particles, which destabilizes the colloids, has been suggested. Further research is under way, and more information should be forthcoming (8). Chemistry of ozone In referring to ozone as an oxidant, chemists often cite the very high negative value of the thermodynamic free energy of reactions, as set forth 'in liquation 5: Oj f 2H 1 -i 2c — HjO + 0 2 (AG" - -400 kJ/mol) (5i in which AG" is the free energy. Although this very large negative value defines the potential for ozone to act as an oxidant, the usefulness of ozone in water treatment is limited by the kinetics of its reactions. In some cases the kinetics arc favorable enough to make ozone a practical oxidant, but this is not generally the case. When ozone reacts with typical water contaminants, rate constants can vary by more than eight orders of magnitude ranging from 107 M ' s"' for the phenolate anion to 10'' M ' s"' for tctrachlorocthylcne (9, 10). Ozone reacts best when it can act as an electron transfer acceptor (for the oxidation of metal ions), as an electrophile (for the oxidation of phenol and other activated aromatics), and as a dipole addition reagent (by addition to carbon-carbon multiple bonds). The rates of oxidation of organic compounds bv ozone arc sevcrelv de pressed, however, by electron-withdrawing suhstituents. For example, ozone reacts poorly with most aliphatic organic halides, such as chloroform. Ozone also docs not react with aliphatic compounds other than those that have easily oxidized groups, such as aldehydes and ketones. Moreover, ozone is not a good oxidant for most specific organic materials in water treatment. Rice has, however, pointed out several exceptions: Ozone has been used to oxidize sulfides, nitrites (to nitrate), cyanides (to cyanate), and some detergents and pesticides ( / / ) . The radical chemistry of ozone. Recent studies from several laboratories support the application of ozone as a chemical oxidant for water and wastewater treatment. Basic research has shown mat ozone decomposes by a complex mechanism that involves the generation of hydroxy! radicals, which .lie among the most reactive oxidizing species (Table 2). Other studies have Rate constanti (!»->«-') Compound Ozon« •;iV,*i*. Benzene involved ozone and some other agent or process, such as UV radiation, hydrogen peroxide, or ultrasound, to develop water treatment processes that arc substantially more powerful than ozone is alone. These new processes arc related chemically to me decomposition mechanisms so elegantly elucidated by Hoigne et a!. (5, 12-14) and Forni ct al. (15) and anticipated much earlier by Taubc and Bray (16). The decomposition of ozone in pure water is shown in Figure 5 as a cyclic chain mechanism; the overall stoiebiometry is shown by Fquation 6: 20, — 30: (6) Decomposition can be initiated by hydroxide ions, formate ions, or a variety of other species, and in pure water the chains arcwery long (17) A single initiation stcp\can cause the decomposition of hundreds of molecules of ozone before the chajn ends. Ozone is unstable at high pHv values because the dc compositionjirocess is initiated by hvdroxidc ions. In the presence of the usual water contaminants, such as bicartionate ions and natural organic matter, the evelie chain shown in Figure 5 cim be broken In the case of bicarbonate, the reaction (liquation 7) is a simple election nans fer process with the hydroxy! radical: Environ So Technol . Vol 21. ^lo 3, 1987 227 superoxide ion (17, 19). But they are also promoted by other water contaminants, such as metal ions. Under practical conditions, the dose of ozone is never enough to satisfy the ultimate demand, and the reactions discussed above generally will stop when the supply is depleted. Typically, this will be long before the organic substances have become mineralized to carbon dioxide Catalytic ozonation processes Ozone can be combined with other processes or agents for more effective water and wastewater treatment than is possible b\ ozonation alone: • • • • HCO., + OH — OH • + HCO., (7) The net effect is to retard the decomposition of ozone. Hoigne and co-workers have shown that increasing the carbonate ion concentration from 10g/m 3 to 100 g/m3 in phosphate-buffered water will approximately double the half-life of ozone at pH 8 (5). Ozone and natural organic matter. When natural organic materials are present, ozone decomposition is accelerated, and the chemistry becomes more complex. There are several reactions that can occur when ozone is added to natural waters: • Free or complexes! metal ions can be oxidized, possibly by one-electron transfer processes, to yield the ozonidc radical anion, which can then initiate the chain decomposition of ozone (17). • The hydroxyl radical can react with aromatic groups in the humic molecules, yielding hydroxylatcd forms, which are then more susceptible to further attack by ozone (18). • The hydroxyl radical can react with aliphatic side chains or fatty acids, usually by hydrogen atom abstraction reactions. The organic radicals formed will generally add dioxygen to form organic peroxides, which decompose by eliminating the superoxide ion. The superoxide ion can then reenter the chain to cause more decomposition of ozone and in228 Environ Sci. Technol.. Vol. 2 1 . No 3. 198Z creased formation of hydroxyl radicals (77, 19). • Ozone can react with carbon-carbon double bonds in the humic molecule (by the usual pathway [20]), first to yield peroxidic intermediates and then to give hydrogen peroxide and carbonyl products. Ozone and synthetic organic substances. If anthropogenic organic materials arc present in water, the same reactions can result in the destruction of these species by ozone, hydroxyl radicals, or both. In general, the hydroxyl radical reacts with organic compounds at rates that essentially arc controlled by diffusion; rate constants typically are between l O ' M ' s ' and 10' M"1 s'"1 (Table 2). Thus, it is possible in principle to induce ozone to act according to an entirely different kind of chemistry than it usually shows in nonaqueous solvents. Indeed, in actual water treatment applications ozone probably never acts according to the classical chemistry that one finds in textbooks that describe nonaqueous systems (20, 21). Classical reactions can occur, but there also will be a parallel set of reactions, often interacting with the first, involving the radical intermediates (especially the very reactive hydroxy! radical), as shown in Figure 5. As Stachelin and Hoigne have noted, these radical processes arc promoted by the products ol the classical reactions, especially the radiation {22 25) ultrasound I26K hydrogen per.xidc <27. 2X). or metallic catalv-ts. such as reduced iron (29). Each of thoc processes probably involves chemistr) similar to that discussed by Hoigne et al. for the basecatalyzed decomposition of ozone (5. 13. 14). Hoigne has identified the hydrogen peroxide anion HO:" a s °nc of the species that can initiate the cyclic chain process shown in Figure 5. This apparently accounts for observations that hydrogen peroxide increases the effectiveness of ozone for removal of organic substances during water treatment (27. 28. 30). Peyton and Glaze (25. 31) have verified the earlier work of Taube (32). who showed that the UV photolysis of ozone in water yields hydrogen peroxide rather than two hydroxyl radicals, as occurs in wet air. Thus, the ozoneUV process resembles the ozone-peroxide process but offers the additional advantage that direct photolysis and photosMithesized processes also ivcw to decompose organic substrates. These ozonation processes are attracting increasing attention because ol their ability to destroy organic substances in water. Figure 6 illustrates the destruction of several chlorinated organic contaminants by ozone with and without UV radiation. (The loss of chloroform |CHCK] and dichlorobromomcthane |CHCI : Br] is caused hv sparging, not by direct reaction with ozone.) In general. UV exposure accelerates the decomposition oAthcsc substances, although the dccay\of he.vachlorobiphenyl (HCB) is retarded. Trials of these processes now m progress or in planning stages aim-at applying them to the renovation of groundwater contaminated with synthetic organic compounds. The advantage is that these processes destroy the con taminants instead of transferring them to another phase, as do air stripping, granular activated carbon ((jACi adsorption, and reverse osmosis The commercial feasibility of these processes is still uncertain. Health effects studies Several studies have attempted to determine the compounds formed by ozonation alone and in combination with other processes in natural waters. Most of these studies have yielded no surprises. Aldehydes, carboxylic acids, and other aliphatic, aromatic, and mixed oxidized forms have been observed. None appear to cause significant toxic effects at the concentrations expected in ozonated waters (3.?) Most bioassuy screening studies have shown that ozonatcd water induces substantially less mutagenic activity than chlorinated water docs One studs showed that ozonation decreased inula genie activity in Rhine River water, whereas the activity increased after the water was treated with chlorine and chlorine dioxide (3). These studies do not necessarily remove all concern about the safety of ozonation for drinking-water treatment. There may very well be byproducts formed that harm human health: they simply have not yet Ivcn Ituind. Il is instructive to recall that chlorine was used for decades betore THMs were discovered in drinking water. The situation with ozone byproducts may be analogous. All of the hcaldi effects studies carried out so far have used preconcentration techniques that may cause some byproducts to decompose during workup. These byproducts include peroxides, epoxides, and conjugated unsaturated aldehydes. Further research is needed if ozonation is to be adopted on a large scale in the United States. Ozone and biological treatment The bypioducis lormed bv oxidation with oz.nne and catalytic ozonation processes arc generally more amenable than are those formed by chlorination processes to removal by biological treatment processes—that is, diey are more biodegradable than dieir precursors are. This is a disadvantage if ozone is to be used as a terminal disinfectant. If applied before filtration, however, ozone can promote biological activity in the filter that will remove organic matter and THM precursors; in the final step, the water can be treated with chlorine or another disinfectant. Ozonation in advance of filtration with GAC has been called the biological activated carbon process This combination of processes has been studied in Western Europe {34-36), where it was pioneered, and in North America i37-3X) DiGiano recently reviewed the subject and concluded that the com bi:!.:i-":i "I pic></iin.iiii<u and OA( !il tr.itii'ii l o i i m o "iL'anic substances but ToSruction of chtorftwiKJ . a ^ ^ ^ ^ ^ ^ # f ^ f ^ 5 S S ^ 3 p 1.0 T^»»_^ Hoxachlorobiphenyt OS ... Bromodichlofomethane *te I \ O TricWo/omethane 0.6 d o 0.4 ""^ / Hexachlorobiphenyl (UV) i 'v 0.2 t Tnchloroethylene (UV) Trichlo-ome.hane (UV) ' \&J,'cr,loroethylene Bromodichloromethane (UV) 10 20 30 40 Tirro (mln) 50 60 70 »A1 pH S-7. o a w o Awe nH« • 1.0-1.« mgrt mil; UV frequency I* 254 ran from «low-pressure marcury l«<np, wi* « f l u x d 0 « J W/L that the effect is not as dramatic as some of its proponents claim {39). Nonetheless, there arc several treatment plants in Europe that arc using the ozone-GAC process, and active removal well beyond the period of GAC exhaustion is reported (36). It is possible that the use of catalytic oxidation processes will increase biodegradability even more than ozone can alone. Ozone system costs Although ozone systems are capital intensive, they offer significant economies of scale. Costs of generating and ^contacting systems vary from one site to another, but about $240()/kg of ozone/day is a plausible figure for a plant producing 900 kg/day of ozone. This would be enough to treat 100 million gal/day of water (4.4 m'/s) with an ozone dose of 2 g/m' (2 ppm) and would require a capital investment of approximately $2 million. Capital costs for systems gencialing 0-5 ku-'h ol i!.-n:"cc aie .ib.ml tliicc times muse ih.tt uenci.iic more than 5(lkiiih. Operating costs of ozone plants also vary, but a range of S0.001-S0.002 ; ni ! seems to IK- typical ol most plants in the United Stales. Ozone production is energy intensive and requires 16kWh/kg and 24 kWh/kg of ozone for oxygenand air-fed systems, respectively. Total treatment costs for ozonation arc in the range of S0.04/m:< to S0.06/m 3 of water for plants that process 10 million-gal.' day and 100 million-gal/day (0.44 mVs and 4.4 nvVs). respectively, assuming an ozone dose of 1 ppm. \ For the future It is likely that the use of ozone in water treatment will increase substantially in North America. In the near future, its principal application is likely to be similar to the new Los Angeles plant, where ozone is used a coagulant aid. Ozonation also will find new applications as a substitute for prechlorination for control of biofouling. taste and cxlor control, and manganese removal. pamculaiK it the m.ivimum contami" nam levels (or THMs are lowered Environ So Techno) Vol 21. No 3. 1987 229 The control of THM precursors, groundwater chloroorganics, and other synthetic organic materials by ozonation is not likely to be successful. Advanced catalytic ozonation processes, however, are showing promise for such applications and will be studied more thoroughly. As the use of ozone for drinking-water treatment increases, particular attention will have to be paid to the use of appropriate analytical methods and separation procedures that will give an ac curate representation of the substances present after oxidation—not just those that survive the work-up procedures Of the byproducts of particular interest, unsaturated aldehydes, epoxides, and peroxides are the most likely to cause harm. As advanced oxidation processes are evaluated further, it is possible that new ozone contacting systems will emerge to take advantage of the inherent rapid mass transfer and chemical reaction rates of radical processes. New designs that combine ozom gcneraiio. with ozone. UV. and peroxide injection may emerge as the best commercial prospects for advanced oxidation processes in water and wastewater treatment. «• I References (1) Rice. k . G . In Safe Drinking Water: The Impact of Chemicals <m a Umited Resource: Rice, R. G. Ed.; Lewis Publishers: 1985: pp. 123-59. (2) Prcndiville. P. W. Ozone Sci. Eng 1986, 8. 77-93 (3) Zocleman. B C. el ai. Environ. Health Perspect. 1982, 46. 197-205. (4) Coste. C : Fiessinger. F. In AWWA Proceedings, Ozonation: Recent Advances and Research Needs; American Water Works Association' Denver, in press (5) Staehclin, J ; Hoigne. J Environ Sci Technol 1982, 16 676-81 Ifil Sprou!. O.J (n AWWA Proceedings. (i;onutiin\ Recent Advances tinti Research Needs. American Water Works Association Denver. ;n press (7) Monk. R D G ct al. J Am. Water WorkAssoc. 1985. 77. 49-54 (8) Reckon. D. A In AWWA Proceedings Ozonation: Recent Advances and Research Needs: American Water Works Association: Denver, in press. (9) Hoigne. J.; Bader. H Water Res 1983. / 7. 173-83 (10) Hoigne, J.. Badcr. H Water Res. 1983, 17. 185-94 (11) Rice. R. G In AWWA Proceedings. Ozonation: Recent Advances and Research Needs: American Water Works Association: Denver, in press. (12) Staehclin, J.; Hoigne, J. Environ. Sci Technol. 1982, 16. 17-22 (13) Buhler. R E . ; Staehelin. J ; Hoigne. J J. Phys. Chem. 1984, 88. 2560-64. (14) Staehelin. J.; Buhler, R E . ; Hoigne. J. J. Phys. Chem 1984, 88. 5999-6004. (15) Forni, L.: Bahnemann. D.; Hart, E.J J Phvs. Chem. 1982, 86. 255-59. (16) Taube. H : Bray. W,C, J Am. Chem So, 1940, 62. 3357-73. (17) Staehclin, J ; Hoigne. J. Vom Wasser 1983, 61. 337-48 (IK) Gurol. M D ; Singer. P C Watei Res 1983, 17. 1173-81 (19) Staehelin. J.. Hoigne. J. Environ Set Techno} 198S, 19. 1206-13 230 Environ Sci. Technol Vol. 21. No 3. 1987 (20) Bliley, P. S. In Ozonation in Organic Chemistry, Vol. I, OUfinic Compounds; Academic Press: New York, 1978, pp. 15-37. (21) Bailey, P S . In Ozonation in Organic Chemistry, Vol. II. Nonolefnic Compounds; Academic Press: New York, 1982; pp. 1842;371-422. (22) Garrison, R. L., Mauk, C. E; Prcngle, H. W , Jr. In First International Symposium on Ozone for Water and Wasle*Kiter Treatment; R i « , G. G.; Browning, M. E.. Eds.; International Ozone Association: Vienna, Va., 1975; pp. 551-77 (23) Peyton. G. R el al Environ. Set. Technol 1982, !6. 448-53 • 24) Glaze. W H. et al. Environ Sci Technol. 1982, 16. 454 58 :.'.5) Peyton. G R Glaze W H. In PhoirchemislD of Environmental Aauatn Svs terns; Zika. R G.: Cooper. W. J Eds.. ACS Symposium Series 327; American Chemical Society Wa.Nhm|!ton. D C . 1986. pr ""* 88 i.'61-Sicrka. K A Ann H I '.-•••), v . Eng. 198S, T. 47 rO i27) Nakayaniii. S. el al (».."i. Si i rny 1979, /. 119-31 l28) Duguet. J. R et al Ozone Sci Eng. 1985. 7.241-58. (29) Chen J W el al AlChE Svmp Ser 1977, 73. 206. (30) Brunei. R.; Bourbigot. M M ; Dore. M Ozone Sci. Eng. 1984,6. 163-83 (M) Ohze. W H e> al "Pilot Scale Evalua imp. of Pb'M'.Oyt.'C Ozonation tor Inhaio methane Precursor Removal." Report of Co operative Agreement CR-80M25: EPA-MXV 52-84-136. NT1S PB84234517: Municipal Environmental Research Laboratory. FPA Cincinnati. 1984. (32) Taube. H Trans. Earad,i\ So, 1957. 5.«. 656. (33) Glaze. W. H. Environ. Health Perspect. 1986,69. 151-57 (34) Sontheimcr, H Translations of Reports on Special Problems of Water Treatment — Vol. 9. Adsorption. EPA-600/9-76-030. Municipal Environmental Research Laboratory. EPA: Cincinnati, 1975. (35) Eberhardt, M. N.; Madsen. S.: Soni heimer, H. "Untersuchungcn zur Vcrwendung Biologisch Arbeilender Aklivkohlcfilter bei der Trinkwasscraufbereitcnder." Report 7; Englcr-Bunle-Inslitut, Karlsruhe University: Karlsruhe. West Germany. 1974 (36) Rice, R. G. el al "Biological Processed in the Treatment ol Municipal Water Sup plies." EPA-6(X)/2-X0-l98n: Municipal Kr. vironmental Research Laboratory. LPA Cincinnati, 1980. (37) Glaze. W. H.; Wallace. J. L. J. Am Water Works Assoc. 1984, 76. 68-75. (38) Maloney. S. W. et al. J Am. Water Works Assoc. 1985, 77. 66-73. (39) DiGiano, F. In AWWA Proceedings. Ozonation: Recent Advances and Research Needs; American Water Works Association: Denver, in press. William li. daze is professor of publit health and director of the Environmental Science and Engineering Program ai UCl-A. He is a /iriniiptil investigator for projects cumerninf! nilulytit ozonation water treatment proi esses, among other areas. '?' 1/ ORGANIZACION PANAMERICANA DE LA SALUD -OPSUN I DAD EJECUTORA DEL PROGRAM DE ACUEDUCTOS RURALES -UNEPAR- DESINFECCION CON GASES OXIDANTES PROYECTO MOGGOD REGION ORIENTAL UNEPAR, GUATEMALA ING. JOSE GILBERTO GONZALEZ DE LEON I 1. ANTECEDENTES. El presente estudio se desarrolló bajo loa lincamientos del "PROYECTO DE COOPERACIÓN TÉCNICA PARA LA EJECUCIÓN DE UN PROYECTO DE DEMOSTRACIÓN DE MEJORAMIENTO DE LA DESINFECCIÓN DE SISTEMAS DE AGUA POTABLE DE PEQUERAS COMUNIDADES Y PUEBLOS A TRAVÉS DEL MOGGOD". Dicha acción ae debe a la promoción que la Organización Panamericana de la Salud, OPS, ha venido desarrollando parael uso de tecnología apropiada para la desinfección del agua en comunidades pequeñas. Dentro de esta política, OPS y CEPIS, han patrocinado diversas investigaciones en el campo de la desinfección del agua. Una de ellas in<Uca al momento que los gases oxidan— tes In situ (MOGGOD), parece ser una de las tecnologías con más perspectivas de ser empleada. Diversas experiencias se han realizado con la desinfección MOGGOD y en diversos países, hasta que en septiembre de 19^7 se realizó un convenio entre el Gobierno de Guatemala, representado por el Instituto de Fomento Municipal INFOM y la Unidad Ejecutora del Programa de Acueductos Rurales UNEPAR, la Organización Panamericana de la Salud a través del Programa de Salud Ambiental y el Programa de las Naciones Unidad para el Desarrollo, celebraron el convenio del proyecto mencionado al inicio, con los siguientes aspectos: 1.1 CONSIDERANDOS: - Que el PNUD ha aprobado la propuesta de Proyecto de D_e mostración de Mejoramiento de la Desinfección de Sistl? mas de^Agua Potable de Pequeñas Comunidades y Pueblos"" a través del MOGGOD y ha proporcionado fondos inicia— les para acciones preparativas de la OPS/HPE en los países colaborantes. - Que la inadecuada desinfección de agua potable es un problema de salud pública muy serio. - Que el MOGGOD tiene buen potencial para evitar o dismi nuir restricciones existentes contra desinfección deX agua potable. » Que el Gobierno y OPS/HPE tienen interés en la explora clon de"posibilidades de la fabricación del MOGGOD en el país. •1 m Que el Gobierno y OPS/HPE ti enen interés en el desarro lio de la tecnología del MOGGOD en el contexto del país - Que elpaís tiene la capacidad tecnológica parainstalar, operar, monitorear, analizar, evaluar el MOGGOD, tecnolo gía y dispositivos y hacer recomendaciones para mejorar el MOGGOD. Derivados de los Considerandos, se determinaron claramente las responsabilidades de la OPS,y del INFOM-UNEPAR, las cuales ae detallan a continuación; 1.2 RESPONSABILIDADES DE LA OPS: - Comprar 2 unidades del dispositivo MOGGOD y repues— tos esenciales y entregar dos unidades al Instituto de Fomento Municipal (INFOM) y una unidad a la Uni— dad Ejecutora del Programa de Acueductos Rurales (UNEPAR). - Proporcionar a la agencia colaborante las instrucci£ nes para la instalación del MOGGOD. *~ - Preparar y entregar manuales de operación y mantenimiento del MOGGOD en español. - Colaborar técnicamente con las agencias/instituciones apropiadas en los asuntos técnicos del MOGGOD re lativos a su instalación, operación, mantenimiento,"" vigilancia, demostración y desarrollo. - Proporcionar material para educación de los ingenieros y operadores. - Establecer con las agencias colaborantes el protocolo para monitorear la eficiencia, efectividad, durabilidad, costos, consumo de sal y electricidad. - Establecer con la agencia colaborante los protocolos para monitorear el nivel de desinfectante'y determinar la duración del desinfectante residual. - Recolectar y analizar la información y datos generados por todas la3 agencias y países e intercambiarlas con todos los participantes. \- Proporcionar criterios de selección de comunidades \ para participar en este proyecto de demostración. - Proporcionar ayuda técnica sobre la fabricación dal del dispositivo de MOGGOD. lo- 2 - Diseminar nueva información técnica en relación de las investigaciones actuales y avances científicos de MOGGOD. - Proporcionar sal común (cloruro de sodio) de pureza adecuada para los dos primeros años de operación de los equipos. 1,3 RESPONSABILIDADES DEL INFOM Y DE UNEPAR: - Seleccionar comunidades apropiadas para participar en este proyecto de demostración bajo los criterios para la selección. - Obtener compromisos y negociar acuerdos con las comunidades para su participación. - Instalar los dispositivos MOGGOD de acuerdo con la3 guías proporcionadas por OPS. - Recolección y análisis de información y los datos £ perativos necesarios para determinar los costos y "~ el consumo: a) de la sal, b) de la electricidad, c) del agua para electrólisis, por metro cúbico del agua tratada. - Determinar la mínima residual práctica para asegu— rar agua libre de patógenos. - Determinar las horas requeridas por mes para operación y mantenimiento, - Determinar en cada sistema la disminución, del residual en la red de distribución. - Monitorear la operación y mantenimiento del M6GGOD. - Identificar las fuentes de sal y su pureza. - Formular recomendaciones^para mejorar el dispositivo MOGGOD y su instalación así como la operación. - Hacer\ recomendaciones sobre la factibilidad de bricación del MOGGOD en el país. fa- - Preparar informes trimestrales sobre el progreso del proyecto de demostración. 2. OBJETIVOS, El objetivo principal de este informe es presentar las experiencias, en relación a la desinfección utilizando la "MEZCLA DE GASES OXIDANTES GENERADOS TU S I W . Ello implicará la relación cuasi cronológica y detalla da de I03 diferentes pasos que hubo que dar, desde la cele" bración del convenio hasta el inicio de operación del equipo seleccionado y el seguimiento a que se sometió para controlar las diferentes'variables que intervienen en el con— junto de experiencias. ' De igual manera previo a la relación, se incluirá 'una información general que permita ubicar al amable lector, en el contexto en que se desarrolló la investigación preliminar. 3. MARCO GEOGRÁFICO Y POBLACIÓN AL. La República de Guatemala tiene un área de 108,689 Km2 y se encuentra localizada al norte de la América Central entre 13° 44 y 17° 50' latitud norte y 88° 33* y 92° 13' longitud oeste. La densidad media* de población es de 70 habitantes por Km^. En 1986 l a R e p ú b l i c a de Guatemala a l c a n z ó una p o b l a c i ó n de ¿.1951.117 h a b i t a n t e s , con una t a s a de c r e c i m i e n t o a n u a l de Z.7$ %. , La d i s t r i b u c i ó n t o t a l de p o b l a c i ó n p o r sexo se p r e s e n t a en la gráfica siguiente: GRÁFICA 1 POBLACIÓN YHJCrRÜEÍs(TlJE POR SEXO ¿&0 1966 SEXO \ POBLACIÓN No. TOTAL 5,195,117 MASCULINO 4.143,071 FEMENINO 4.052,046 \ i 100. 50.6 49.4 i — FUENTE: Guatemala en C i r r a s de S a l u d , MSP y AS. La población total se encuentra dispersa en unos 1# 640 nu'"leos d Q población, de los cuales 9&% tiene menos de'2,000 habitantes. E303 núcleos poblacionales comprenden aproximadamente el 64$ de I a población total. La población está dividida en sector urbano y rural, por definición, se entiende por población urbana, la que habita en lftS 326 cabeceras municipales y la ciudad capi— tal. 4. MARCO INSTITUCIONAL. UNEPAR, e s la Unidad Ejecutora del Programa de Acue— ductos Rurales. Es una dependencia del Ministerio de S a — lud Publica y Asistencia Social. Fue creada e*1 1975, sustituyendo al Departamento de Inge— niería Sagitaria de la División de Saneamiento Ambiental. Opera a ni-VQl de Dirección, dependiendo directamente del Ministerio de Salud Pública y Asistencia Social. Como objetivo fundamental UNEPAR tiene'el proveer agua potable al#sector de ],a población rural; trabajando con los "Comités Oficiales de Agua Potable", quienes se con vierten eA el enlace dinámico entre la institución y las co munidades* UNEPAR,atiende t o d o s l o s departamentos de l a R e p ú b l i c a con excepción de El P e t e n , e j e r c i e n d o su acción a t r a v é s de! - Dit*ecclón y Administración con sede en la ciudad capital. - Re/íi°n Central, con sede en la ciudad de Guatemala. - Región Oriental, con sede en la ciudad de Chiquimula - Región Norte, con sede en la ciudad de Cobán. - Región Occidental, con sede en la ciudad de' Quetzalten ango. $* REGIÓN ORXjNIAIj. En el presente infórmele hará una ampliación sobre es Región, dndo que la Dirección de UNEPAR delegó la responsabilidad do la experiencia del MOGGOD en ella. 5.1 COBEKTURA. ^ \ • La Región Oriental, desarrolla-su acción én 4 departamentos de la Zona\Nor-Orieñtal, cubriendo una superficie estimada de 12\,530 Km2. La gráfica No. 2 muestra el mapa de la República de Guatemala, con el área de acción de la Región. 5 QRAFICA ffo. 2 REPUBLICA DE GUATEMALA • Un detalle de esa área se presenta en la gráfica No.- 3 La cobertura de servicios en cada uno de los departamentos se muestra respectivamente así: - Gráfica No, 4: El Progreso. - Gráfica No. 5: Zacapa. - Gráfica No, 6: Chiquimula. - Gráfica No. 7: Izabal. La gráfica No. 8 presenta un resumen cuantitativo de a tención, "~ GRÁFICA No. 8 COBERTURA REGIÓN ORIENTAL DEPARTAMENTOS - MUNICIPIOS - COMUNIDADES DEPARTAMENTO MUNICIPIOS ATENDIDOS SISTEMAS CONSTRUIDOS COMUNIDADES BENEFICIADAS CHIQUIMULA 11 17 31 ZACAPA 10 14 33 IZABAL 4 25 4o EL PROGRESO 5 6 10 r TOTALES: 30 62 114 FUENTE: Región Oriental de UNEPAR 6. DESARROLLO DE LA INVESTIGACIÓN. De acuerdo con lo s términos del convenio firmado en Septiembre del 87, se' tuvo conocimiento que el CEPIS orga— nizaría en Lima.,Perú, el "Primer Seminario Internacional sobre Desinfección por Oxidantes Mezclados". La participación en dicho seminar!o llevaba implíci\to el presentar algu ñas experiencias, por lo que la Dirección de UNEPAR, désig~ nó al suscrito#para re alizar la investigación de campo, Se recibió a fina les de Octubre el equipo y se comenzó a elaborar las estrategias de trabajo, las cuales se descri birán a continuación: 7 QEAFICA Ho, 3 0CB?:an:-RA R S J I ; iT C R U ^ A L MUNICH MC3 3A SlTi'^/iS • ' 2 - \ 'JC i-:L:"; i DA J:J3 ;OJL.W^:; ii^^.vicj.-.j.. 114- 7L3,33(' CfRAPICA F o . 4 i-n-'iiioirios •" 1 ^ 'V, •• . . c COMlFii),* IXiS rci'L^cio'i :i-;:."j.;,iCj'-;D:'i 5 6 10 9,933 9 QRAJICA Ho. 5 J J i A;ti'A,-; J" .11' DU ^AC.li'A r.u::ic;irJ.C5 1C SIL'TJ-:A:3 H CO;:U-'1UA)^ 33 iCiJiAJU;:: - • ^ ^ . . V . I A D A 1V*7 10 QRAFICA Ho. 6 D E P ^ i f ^ r ' P O 13 C'.il.t'JJi.iULA MUiiiciPicg 11 SIGO-IAS 17 CC»'.U'TJ DA D.23 31 F0 3LAGIC'n DTCFiCUDA 18,1^5 11 ORJLPICA. N o . 7 )J1 A.'i'i'Ai .Z.. i'C JZ l^AJ-Jj 1". : : ..r;ir*fi i i l 5 I-iUniCli'lOS 23 cv.:u':'i.")/,jj.i IT:-L". C i C: ^ ' " ' i n T L ^ A *; v- -'•• - > - - • - ".TV 6.1 EQUIPO La unidad "0X1" producido por Oxidizers Inc, 4990 Euclid Road, Virginia Beach, VA 23^62 entregado a UNEPAR, es una unidad que consta de una celda electrolítica. La gráfica No. 9 muestra una reproducción de la celda con sus componentes. En esta celda se produce una mejz cía de oxidantes consistentes en cloro, oxígeno y perjo xido de hidrógeno en el compratimiento del ánodo. ~" ^En el compartimiento del cátodo la celda produce hidrógeno én forma gaseosa e hidróxido de sodio en for ma líquida. "" El ánodo y el cátodo están separados por una membrana semipermeable. La otra parte de la unidad es un autotransformador de corriente que utiliza 110 - 120 VAC a 60 Hz. La gráfica No. 10 muestra el autotransformador en vista anterior y posterior. 6.2 OPERACIÓN DEL EQUIPO. La unidad MOGGOD utiliza cristales'de hidróxido de^sodio en el compartimiento del ánodo, ambos en solji ción con agua destilada. ' "" La sal debe ser de alta calidad, es decir cumplir con las normas^Sterling TNA5 u otro equivalente con ba ja concentración de calcio. "~ La electrólisis de estas dos soluciones a un gasto energético de 3 a 10 voltios produce compuestos oxidan tes mencionados anteriormente. "~ Los elementos oxígeno y cloro oon absorvidos fuera del ánodo por un tubo de Polipropileno conectado a un venturi. Para la investigación se utilizó un inyector MAZZEL, el cual se instaló cerca del punto de restricción creado por una válvula de compuerta, con lo cual se crea una presión diferencial la cual no debe ser me ñor del ZU% para que se produzca el vacío que succione los oxidantes producidos. La instalación la muestra la gráfica No. 11 El exceso de hidróxido de sodio líquido producido en el proceso es drenado tal y como muestra la gráfica No. 11. El gas hidrogeno proveniente del cátodo es más 1JL viano que el aire y es eliminado a la atmósfera por un sistema de ventilación ubicado en el techo de la insta lación. " f La generación de gasees controlada por por la electrólisis de la solución. La velocidad de la electrólisis se controla variando la corriente eléctrica 13 ORIFICA Ho. 9 CELDA ELECTROLÍTICA 1. Compartimiento del ánodo 2. Compartimiento del cátodo 3. Orificio/agua soda caustica 4. Tapón plástico orificio 3 5. Orificio/agua sal 6. Tapón plástico orificio 5 7. Visor del nirel de sal 8. Drenaje de soluoión de sal 9. Membrana semipermeable 10. SrJida de mesóla de gases 11. Drenaje de coda caustica 12. Ventilación del hidrogeno QRAFICA N o . 10 AUTOTEANSroEMADOR [ 4MP5 -(LO)*y^y^ VOIT5 0 3 VISTA ANTERIOR VISTA POSTERIOR 1. Boton do oontrol v o l t a j e 2. Kedidor de c o r r i e n t e (cjaporios) 3 . F u s i b l e ( 3 amporios) 4» Cordon de Corriemte 5 . Conootoroa de e a l i d a o o i r i e n t e D.C. ORAFICA N o . 1 1 m INST1LACI0H KiUIPO i 16 que fluye por los electrodos y a su vez la corriente eléctrica se controla cambiando el voltaje usando un f reóstato o botón de control como se muestra en la grafi ca No. 10. ~" Con lo dicho anteriormente se concluye que el d e — sinfcctsjite residual que se d©sce, se obtiene ajustando únicamente el botón de control del autotransformador. Este residual se lee con un comparador en el sistema de distribución 6.3 SELECCIÓN DE LA COMUNIDAD, Dentro de la responsabilidad de UNEPAR, quedó la selección de la comunidad para desarrollar la investiga ción. El criterio de selección quedaba determinado por los siguientes parámetros. - Ubicación: Lo suficientemente cerca de un laboratorio con capacJL dad para hacer análisis bactriológicos y próxima a la Oficina Regional para facilitar el seguimiento. - Tamaño de la población * W£r'9~5üü y lZOTThabitantes. - Servicios existentes: Energía eléctrica y un sistema de agua con redes de distribución para un servicio continuo. - Calidad bacteriológica y físico-química del agua: Agua con necesidad de desinfección y bajo nivel de tur biedad. "* "* Organización de la comunidad: L"a comunidad debe contar con una junta administradora o Comité de Agua Potable y proporcionar un operador de la unidad de desinfección. En base en los aspectos anteriores y revisando el inventario de comunidades abastecidad con sistemas de agua potable oe seleccionó la aldea PUEBLO NUEVO, en el municipio de Usumatlán, del departamento de Zacapa. Las características que la población reunía se des criben a continuación: ~ - UBICACIÓN: La comunidad se encuentra a la altura del kilómetro 114 de la carretera CA-9 Norte y a 56^kilómetros de la ciudad do Chiquimula. sede da la Región Oriental de UNEPAR. 17 En la ciudad se contó con la colaboración del laboratorio de la Jefatura de Área de Salud y'del laboratorio del Centro,Unlvesitario del Nor-Oriente, CUNORI. La población se encuentra en la cuenca del Río Motagua, el río más grande de Guatemala y en sus orillas corre el Río La Palmilla que aguas arriba permite la obra de captación que surte el sistema de agua. Dista de la cabecera Municipal, Usumatlán, 8 kilómetros y de la c¿ becera departamental. Zacapa, hO kilómetros. La situación puede observarse en la gráfica No. 12. TAMAfiO DE LA POBLACIÓN; Estudios hechos para el mejoramiento del actual acue— ducto, indican que cuenta con 90 viviendas con una estimación, de 5^0 habitantes en la zona de mayor concentración, SERVICIOS EXISTENTES! Carretera de terracería con una longitud de 2 kilómetros que interconecta con la carretera CA-9 Norte. Escuela y edificios religiosos (dos). Energía Eléctrica a nivel domiciliar. Se carece de alumbrado público. ' Servicios de Salud, prestados por el puesto de Salud de la Cabecera Municipal. Sistema de Agua potable, construido en 1976, con capta ción de fuente superficial sin tratamiento. El servia ció cuenta actualmente con 60 conexiones domiciliares, un tanque de almacenamiento de 30 M3¿ con un caudal de entrada de 1.4 L/S equivalente a 120,960 litros dia rios y una longitud total de 4506.00 metros de tubería instalada. CALIDAD BACTERIOLÓGICA; Siendo una fuente superficial era de esperarse que existiera algún rango de contaminación, sobremodo porque en los alrededores de la obra de captación hay 6 viviendas que utilizan el agua del río La Palmilla para resolver todas sus necesidades. Efectuado el análisis se comprobó la hipótesis y la gráfica No. 13, muestra el resultado del análisis previo a la investigación. No fue posible analizar y comparar la turbiedad y color con los patrones usuales, pero a simple vista el agua presenta un aspecto libre de turbiedad e incolora, ORGANIZACIÓN COMUNAL; Ta comunidad cuenta con un Comité Pro-Mejoramiento, cu yos miembros sobre todo el Presidente y Vico-Presiden^ te, prestaron una colaboración y un entusiasmo encomLa ble al desarrollo de la experiencia. El Vicepresidente fue el operador auxiliar en el control y manteni miento del equipo. 18 GRAFICA N o . 12 MUNIC1PI0 J)E USUMATUN \ PUEBLO HUEVD \ \ CORSTRUCCION 3I3TEMA C0HEXI0HE3 DO!JICILIJ?.RES TUBERIA IHSTALADA CAUDAL DISPONIBLE 1,976 60 4,506 Mta 1.4 L/S GRAFICA No. 13 RESUMEN DE RESULTADOS ANALISIS BACTERIOLOGICOS ^\FECHAS CONDICIONES\^ 27-10-87 N o . MEMBRANAS FILTRANTES 2 MEDIO SELECTIVO EN DO VOLUMEN MUESTRA 25 N o . COLONIAS COLIFORMES COLIFORMES p / 1 0 0 Ml TIEMPO INC. \ .._. ...... 216 12-11-87 19-11-87 2 . ENDO 25 25-11-87 2 2 ENDO ENDO 25 25 68 0 1,700 0 24 Hrs. 24 H r s . * 5,400 24 Hra. r 24 H r s . 6.4 INSTALACIÓN DEL EQUIPO: P a r a r e a l i z a r e l m o n t a j e , se e s c o g i ó un punto de l a l í n e a de conducción s i t u a d o a 15.00 m. d e l t a n q u e de almacenamiento. Se d i s e ñ ó l a c a s e t a de p r o t e c c i ó n del equipo, siguiendo l a s instrucciones del f a b r i c a n t e en cuanto a l a v e n t i l a c i ó n i n f e r i o r y s u p e r i o r p a r a evacuación de l o s g a s e s t a n t o l o s l i v i a n o s y pesados en relación al a i r e . Las d i m e n s i o n e s de l a c a s e t a f u e r o n : - Largo: 1.20 m. - Ancho: 1.20 m; - Alto: 2.00 ra. Fué construida con blocks de concreto de 0.20x0.20 x0.40 m. y una cubierta de lámina galvanizada. Se proveyó de una caja de registro, utilizada como fesumidero del rebalse del hldróxido de sodio líquido. Las do3 unidades del equipo fueron colocadas en planchas de concreto a 1.40 m. del nivel del suelo. La colocación del venturi ya se ilustró anteriormente en la gráfica No. 11. 6.5 GASTOS DE INSTALACIÓN Y MONTAJE: 4 La instalación y montaje del equipo, exigió diver sas actividades e inversiones las cuales se enumeran 'a continuación: 6.5.1 MATERIALES CONSTRUCCIÓN CASETA: Arena de río Blóck cemento 0.20x0.20 xO.40 Bolsas de cemento Bolsas de cal Varillas de hierro 3/8 Alambre amarre calibre 18 Clavo de 3» Clavo de lámina Lámina 6» Bisagras 3" Puerta Candado Mv 0,5 U 100 qq 6 qq 1 U " 6 Lb; 5 Lb. 5 Lb. 1 U 3 U 2 U 1 U 1 TOTAL: Q. 9.00 » 45.00 " 44.30 " 4.50 ", 2 3 ; 54 »' 4 . 0 0 " 4.00 » 0.6*0 « 10.80 » 2.00 " 50.00 " 15.00 Q212.9^ 21 6.5.2 MATERIALES Y ACCESORIOS INSTALACION EQUIPO: Llaves de paso de 1/2" Valvula de compuerta de 2" Adaptadores Macho PVC de 2" Adaptadores Macho PVC de 1 1/2" Tees Reductora3 PVC de 2" x 1/2" Codoa PVC de 1/2" x 90° Tubo PVC de 2" 160 PSI Tubo PVC de 1/2" S o l v e n t e p a r a PVC r f g i d o Alambre c a l i b r e 10 C l n t a de a i s l a r Cinta teflon Toma c o r r i e n t e A i s l a d o r e s de 1 1/2" F l i p - u n 15 Amp. u u 2 Q. 1 tf 104.00 u 2 it 5.44 u 4 it 5.73 u u TUEO 2 2 1 1 tt 9.65 1.14 30;12 TUBO • _ « . . . . m. U U U U U . i/a 140 1 1 1 14 1 TOTAL: ii it it ti n it 6.50 7;oo 8:45 9i;oo 2;50 2:50 tf 2;95 n 10.50 ». 14.50 Q. 302.03 it 6.5.3 HERRAMIENTA Y EQUIPO; - Prensa de banco de 2" Llaves Stilson No. 24 Cubetas para concreto Nivel Plomada Cuchara de albafiil Piochas Palas punta redonda Escuadrilongo NOTAJ 1/2" 1 2 4 1 2 3 3 3 1 Eate equipo fue p r o p o r c i o n a d o ' p o r l a Region O r i e n t a l de UNEPAR, s i n c o a t o . 6 . 5 . 4 EQUIPO ESPECIFICO Y REACTIVO: - Comparfmetro - Yodur.o de potasio - Almidon «- ForrnolX - Soda caustica - Hipoclorito de calcio 65* -\ - Agua deatilada - Cristalerfa u gr. ti 3 *" 6.42 2 14 ti - it 13;00 26.21 5.00 87.43 — gi*: ml. Lb, Lb. Lts. - 1 40 TOTAL: Q. »t it it Q. 20.00 10.00 0.20 l;6o 22 6.5.5 MANODEOBRA: Instalacion 5 o p e r a r i o s / 5 df as Seguimiento c o n t r o l tnueatrass 1 p e r s o n a / 3 d£as Operacion Equlpo 1 persona /15 dfas TOTAL: 6.5.6 Q. 200.00 it 30.00 it 169.95 Q. 399.95 TRANSPORTE: - Viajes de 140 Kms. - Viajes de 140 Km3. 7 2 TOTAL: Q. 203.00 17*4o Q. 220.40 if. 6.6 OPERACION Y SEGUIMIENTO: • — — — — — — — — • « . - — • — — _ _ _ _ _ _ _ — . t La puesta en accion del equlpo de deslnfeccion, se realizo slguiendo la3 instrucclones proporcionadas por el fabricante. Hubo .dudas e incertidumbres, las cuales fueron 3ubsanadas durante la operacion, la'cual confirmo o indico la3/modificaclones pertinentes. La operacion y seguimiento se realizo en diferen— tes^etapas y con mecanismos de'control adecuados al #al parametro que se deseaba medir, los cuales se trataran de describir en las slguientes lfneas. 6 . 6 . 1 ANALISIS BACTERI0L00IC03: Para determinar la bondad y/o en su caso ine^ ficacia del equipo se practicaron analisis bacteriologicos antes y durante la investigacion. En la grafica No. 13 se muestra la tendencia de los analisis^practicados, los cuales se practicaron con el metodo de las Mombranas Filtrantes. 6 . 6 . 2 DETERMBJACION DE DEMANDA DE CLORO: Se utilizo un metodo de carapo con lo cual se obtiene una dete rminacion ^aproximada. El^proc edimi en to consistio en preparaf una solu— cion que conttivi era 1 gr/lit de cloro. Esta solu cion se prepare en laboratorio con hipoclorito de calcio al 65/6 y\ se agrego al agua que se iba a s£ meter al tratamx*ento, para determinar por* comparla cion la cantidad de cloro necesaria para el trata miento. 23 GRAFICA N o . 1 4 RESUMES GENERAL OASTOS DIBECTOS RSNQLOir MOHTO MATERIALES CASETA 212.94 HATERIALE3 IRSTALACION 302.03 BQUIPO T REACTIVCS 87.43 HAHO OBRA 399.95 TRAN3P0RTE 220.40 SUBTOTAL IMPKEVISTOS 1C^t TOTAL 1222.75 122.2b 1345.03 6.6.3 OPERAGION DEL EQUIPO: Se inicio de acuerdo con las especificaciones del fabricante y paralelamente se iniciaron los controles de los diferentes parametros involucrados en la experiencia, los cuales se mues— tran en los siguientes graficos: - Lectura de gravedad especffica del Na OH, grafico No. 15.' Las lecturas fueron hechas tres veces al dfa. - Lectura de gravedad especifica del Na U, grafi^ co No. 16. Las lecturas fueron hechas tres v_e ces al dfa. s * - Control^de cloro residual, grafico No. 17. Se practico una lectura por dfa en diferentes pun toa de la red de distribucion, "~ - Control del Ph, grafico No. 17. Se practico una lectura *por dfa, juntamente con lectura del cloro residual. - Demanda de Na OH en gr, grafico No.*13. ca el consume del hidroxido por dfa. • > Indi• - Demanda de Na C/ en Lb. , grafico No. 13. Indi ca el con sumo de sal por dfa. "~ 4 - Demanda de Energfa Electrica, grafico No. 19. Este dato globaliza el con3umo total diario de energfa electrica en kilowatios. El consumo diario incluye la utilizacion de la energfa ga ra el alumbrado de la vivienda y aparatps elec[ tricos (radio-grabadora). "~ RESULTADOS! ' Es prematuro emitir opinion sobre resaltados fina les, los cuales se consideren concluyentes, sobre todo por el'poco tiempo que hubo disponible para la invest^ gacion. \ Los resultados obtenidos ppr otra parte seran vis_ tos un tanto subjetivamente porxel autor de e3te infor me, dado que fue el conductor de\la experiencia. Sin embargo se tratara en lo posible lograr el mayor grado de objetividad. -\ Teniendo en cuanta lo positivo que sera el llegar a conclusiones imparciales que beneficien al area r u — ral de nuestros pafses. 25 T^- r-i rH CM t— m in t— t— rH rH r-i »-« rH r-i O Q Q 8 8 CM rH rH R R r-l R CM o M f=* O iH ON lf\ CM rH r-i rH R R •% o -*: o • g •* te t— Q R R CM a rH S § " in CM R rH t~t rH in lT\ CM CM R fc % t-t• • CM * CM ri CM t-t • t rH t- CM CM •fc rH IT* — rr H R t-H rH r-t t-i rH IA CM CM •». rH •* H R R CM •% « t R CM • h ri in t— H •* rH rH rH § m g t-i t-i #» rH CM CM » •» rH rH CM «*•» •* R CM m • » * g • h rH m § 4r\ r-i rH R in CM «k iH rH § *A CM «K iH NO HP* R • h M CM CM r-i § H m rH •H to «% •» iH Q o M CM • t CO 9* CM CM r-» r-« ITS CM r-l 3,< P»/3 // Ha 8 «• CO 8 «• CM rH O o•• e- t-i 26 O r-l N o 8 O 8 <T\ O M 8 CO vO o <: o M a $25 o 3 R t— i-l NO 8 § tn 8 R 8 R R R R rO CM 8 *• oo CM 27 QRAPICA No. 17 CONTROL CLORO RESIDUAL Y Ph DIA AMPERAJE UN I DAD LECTURA COMPARIMETRO CLORO RESIDUAL Ph 1 7 2 6 0.3 7.6 3 5 0.3 3.2 4 6 0> 7.6 5 6 6 < 0.4 * 0.4 3.2 6 0.4 7.3 7 6 0.3 3.2 3 6 0.4 3.2 9 6 < 0.4 7.6 10 6 <. 0.4 8.2 11 6 0.4 8.2 12 - - - 13 — - — 14 6 0.4 v. 15 6 0.4 77.8 ^N _ \ < ?.<•' HP. A FTC A !Ir>. 1.3 "COKSUMO REACTIVDS" DIA SODA SAL 1 42.9 grs. 8 Oz. 2 85.8 Qrs. 8 Oz. 3 42.9 gra. 8 Oz. 4 42.9 ffra. 8 Oz. 5 75.0 grs.' 6 Oz. 6 64.3 £TS. 6 Oz. 7 64O grs. 6 Oz. 8 42.9 ffTS. 8 Oz. 9 42.9 ffrs. 8 Oz. - 8 Oz. 10 * 11 _. — — 12 - - - 13 - - -. H .- - - 15 8 Oz. _ _ _ 12 Oz. \ 8 Oz. \ - 29 GRAFIGA No. 19 CONSUMO EtfEHQIA ELECTBICA LECTUBA IFICIAL LECTUBA PINAL COHSUMO 1 404 406 2 KT. 2 406 403 2 KT. 3 408 409 1 KT. 4 409 411 2 KT. 5 411 413 2 KT. 6 413 415 2 KT. 7 415 417 2 KT. a 417 419 2 Kv. 9 419 422 3 Kv. 10 422 424 2 KT. 11 424 426 2 KT. DIA : . 12 - - - 13 - - - 14 426 431 5 KT. « 431 434 - 3 Kr, I 6.7.1 A3PECT0S CUALITATIVOS: •• Partiendo de cero, la experiencia fue sumamente^valioaa ya que fue posible poner en opera— cion un equipo desconocido, teniendo situaciones adversas derivadas de lo inflexible de un aparato gubernamental administrative - Una tecnologfa nueva en el pafs, fue puesta a prueba, en las condicicnes reale3 del area rural. Nada se invento y la experiencia fue reji lizada y controlada con los recursos escasos con'que cuentan las instituciones gubernamenta les. - La experiencia fue rutinaria y rigurosamente controlada con los elementoa que fue posible disponer. - El equipo es funcional y, a juicio del que su.3 cribe este informe, produce buenos resultados con una operacion sumamente sencilla en contra posicion corf otros sistemas de desinfeccion re coinendado3 para el area rural. 6.7.2 ASPECTOS CUANTITATIVOS: Solamente se analizaran algunos de los a s — pectos mas significativos, ya que se insiste en que es necesario desarrollar la experiencia con: - Mayor tiempo de investigacion. - Equipo adecuado para analisis,bacteriologicos y examenes f£sico-quimicos. * t - Resurso humano altamente c a l i f i c a d o , en contr£ l e s de calideddel agua. " Entre los aspectos a sefialar caben p r i n c i p a l roente l o s s i g u i e n t e s : ~" El MOGGOD, produjo l a cantidad de gases oxi dantea, n e c e s a r i a en e s t e c a s o , para disminuirW terminar con los i n d i c a d o r e s b a c t e r i o l o g i c o s que se^encontraron en e l agua antes de l a realiza—-\ cion de l a e x p e r i e n c i a . ' , \ Debe hacerse n o t a r que, como lo muestra el grafico"No. 13, despues de l a primera toma de muestra, ya efectuandose el t r a t a m i e n t o e l anally s i s b a c t e r i o l o g i c o aun indicaba p r e s e n c i a de co~ liformes. Queda la incognita de saber si se debio a haber sacado la muestra dos dfas despues de haberse iniciado el proceso de desinfeccion, se decidio desinfectar el tanque de almacenamiento y luego se tomo nuevamente larauostra,la cual indico ausencia de coliformes. En eate caso... ? influirfa el hecho de haberse desinfectado el tanque o serfa que para hacer el analisis se utilizo reactivos y mate— riales nuevos ? La grafica No, 13 indica el^resultado de los di^ ferentes analisis'bacteriologicos practicados."" La grafica No. 13, debe interpretarse con la siguiente informacion: 27-10-6*7? Agua sin ninguna clase de tratamiento, antes de iniciarse la experiencia 12-11-0*7? Agua analizada despues de dos dias de iniciado el tratamiento. 19-11-6*7? Ag\ia analizada despues de nueve dfas de tratamiento y luego de haberse djj sinfectado el tanque de almacenamien to. "" 25-11-6*7? Agua analizada despues de quince dias de tratamiento. OBSSRVACIONSS FINALES 5] suscrito quiore H^jar con.jt"icia de :;a roc'ncci:'iionto a las autoridndes de la CPS y do UIH2PAR quo or'-ivioron atontos a prestar el apoyo necesario par? /?1 ''osarro llo de la exporiencia. Reconocimiento especial a las autoridades de la Jofnt'jrn de Area de Salud de Chiquimula y a la Direccion del Centro Universitario del Nbr-Oriente en cuyos laboratories y con su personal calificado se reali-o el control de la calidad del agua. Finalmente al personal de la Region Oriental que dodico lo mejor de su esfuerzo para apoyar el desarrollo del proyecto en sus diversas fases y sobre todo en la prepare:on del presente informe y el documental audiovisual correspnn diente. Ing. Jose Ollbortc ^cn-aler. Jefe Region Oriental UHEPAR JASCH DIV1:JIL. .L* .*3.L...U.:-r.L'.'TC JUL i-JJlO i:..--\::"j i: J..L -i:... ^-I : AO:J ::naca::uc ion ^L i^Tcx J.J i:..i-_;.._^..';.j J^ :-.-iLr.i:-.jic;; •i-'O. CO/07. A^^i ^uj/imiOLcaioo Muostra dc. FUEPLO IJUEVC UZUN:-TI».)T {ZCM'. 27-10-27. Fecha en que fue captada la inuestra:. 15*20 Hora en que fue ce.ptada la muestra:_ Sitio: Fuente: J. Urn r-!-.'. S e r v i c i o , Do o i c i l j f r i p , ._ S e r y i c j o Doinici 1 j p r j o . P e r s o n a que c a p t o l a m u e s t r a : c g c R CHACTITI !Vt;cs ( 'vrai'.M'JL F e c h a en que d i o p r i n c i p i o e l examen:, , , 27-ipr87. CAJIACTEHES GENERALES: Colors , Incoloro S u s t a n c i a en s u s p e n s i o n : I n v e s t i g a c i o n d e l Grupo _Aspecto: £1- IP. _____ Coliforme Incubacion a 35 C No. Membrana Medio Filtrantes Selectivo 2 KtTDO Volumen Colonia Coliformes Tiempo Muestra Coliforme p/100 ml Inob. 25 216 5, 400 ?.\ nr.. O b s e r v a c i o n e s v F o r F R o s o n t - r Munisro <.lQ.Co1.oni s J e l . '. ; r" <o ^ - . t f r r H . e C o n c l u s i o n e s : " - - - ^ » ° E > " i ' " £ * " - ^ CO?T.T.VC HIT : . - O . Fecha: ^c ifJJZc -••>i3 3 C. JASCH DIVLliJjLC..". :),J .V^.'JLi-I.T.'iX. '.)Jij LIDIG J.C.A J_;L i.-j'^C-'X J.j i"..J-"-i---.Ao Di-I ..•'J.LJ.'-L.JXCJ. n A^i=-=iLi £ o..85/az^. LiAj'i^lIGLOCrlCO: Huestrn. do^fejBgLQJIIIBg-O'UZPMATifllf ZACAPA« Fecha en que 'fue c a p t a d a l a m u e s t r a : 11,9^.11 -Q7* Hora en cue fue c a n t a d a l a m u e s t r a : , , t l t ^ Hrs BMf Sitio s Pueblo Nuevo .. ___ Fuente: Coneccfon D o m i c l l i a r i a : fcuSEBIO JAOINIO) Persona cue c a p t o l a muestra:. .OSCAR CjiAGllfN .RAMOS. TOBPAR* Fecha en cue dio p r i n c i p i o e l examen?, 119-11TQ?» , — CARACTERES GENERALES: Color: Incoloro Aspecto:_ S u s t a n c i a en s u s p e n s i o n : _ ^ _ _ I n v e s t i g a c i o n d e l Grupo Coliforme Incubacion a 35 C No. Membrana Medio Filtrantes Selectivo %0 Claro Volumen Muestra Colonia Coliforme Coliformes p/100 ml 25 0 0 Tiempo Inob. 2^ Hr: V / Observacionesf/ Ppr Np P r e s e n t a r Mi»g«»Jg& t oge--d«-co3on1afl d e l Grupo C o n n i u s i o n L : ^ 0 ^ f o r e m TptQal «»EL AGtf£ S i FS: APTA PARA EL COHSlMO HUMAN0Fecha:'_ > ,/' : Nombre:, • v /fl?aAw m Ill /fdjJ* l/oJ'^h^ , MARIA ADELA VALDES C . C • JASCH Dl-/"_.'JiL". .X.j O,L!..U .M.'l'.'Tt C .1 •„•£• ; ..j'j.'C'X- .-'•-< 1...J-..; I..AJIC J.JL ».J D J .•.'lLa.-L-.'Jj.C; 82/87. *'Q«, , 7 7 ;,, " -- Muostra dc: PU£BLQ MUEVO, (UZUMATLAN) ZACAPA. Fecha en que fue captada la muestra: . 12-11-37? Hora en cue fue captada la muestra? iQfP^H? 5 * w Pueblo uevo Sitio: „ Fuente: , 3 e r v l c i o DomicJ-llario CflUJJSVIO JACINTO), P e r s o n a oue capto l a muestra? , OgCAfl,CHAgJVN. HAMQS UNKPARj.. Fecha en que d i o p r i n c l p i o e l examen? r . 12-11787» ., , CAHACTERES GENERALES: Cairo Incoloro _Aspecto! ColorJ_„_ Sustancla en suspension: _ _ _ Pequefia.3 P a r t i c u l a s . Investigacion del Grupo Coliforme Incubacion a 35 C No, Membrana Medio Filtrantes Selectlvo ENDO 2 Volumen Muestra Colonia Coliforme 25 68 Coliformes p/100 ml Tiempo I nob. 24- Hrs, 1,700 0b se r v a c i o r i e s : Por Presentar "umero de Colonlas d e l Grupo.Coliforme Total Pn»,o,i<Ck**' 2J2D.AGUA NO ES APTA PARA,_JL CONSUMO HUMANO. ^onCjJJ.bxpnes;^.—„ J^%/L_ yfifi^y' • • 13-11-82, _ ~ y ..^mhTetS^^^^rJ^.^vJ^J JEFATURA j-fcHIA ADBLA VALDEa C . suramsc-R K JEFATUU AI a-JIQUIA'.U?-A, Gr f*~j~7~ DE - ' • T CS .1 I.'. Mr " -• C y :.•<*$ A,' f l N S / W O SOBRBl D E G R A D A C E O N OHITEROKNTES PO.R K M P L E O J3JE L,A AIM I O N I D1S O-OS O Z O N O C L O R AG E ON Dr Omar J . Simoni BUENOS AIRES, ARGENTINA, Noviembre 1987 V E N S A Y Q 3 Q 3 R E P E O R A D A O X OIM DKTKROENTECS AIM T O N I C O S POR E M P L E O DE LA D E O Z O N O O L O R A O I O N Dr. OMAR J. SiMOIMI D i r e c t o r del Fstudio Consultor en Contarninaeion Ambiental - EFJCA - Maturin 2887, Buenos A i r e s , A r g e n t i n a Asesor Tecnico de la Federacion A r g e n t i n a de Aguas Cjaseosas y Bebidas sin Alcohol D i r e c t o r Tecnico de CIMES - C o n t r o l I n t e g r a l Metodologico de Sodas lNTRODUCCION Se verifico la propiedad del ozonoclorador marca GIDOX en la elimina cion de detergentes anionicos, evaluados cuantitativamente como sustanoias reactivas ai azul de ortotoluidina. TECNICA DE EVALUACION Se prepararon soluciones de detergentes tipo en concentraciones crecientes, de acuerdo a las normas IRAN - Instituto Racionalizador Argentino de Materiales -. Se procedio al llenado con agua ozonoclorada con una concentracion de 10.2 mg/1 de oxidante. Se realizaron luego los ensayos quimicos para verificar los valores residuales en.las soluciones tipo al cabo de 24 y 48 horas. Tabla C0NCLUS10NES Se constato l\a alta eficacia destructiva de la ozonocloracion sobre las cadenas hidrocarbonadas de un tensioactivo anionico lineal. Los estudios fueuros deberan encaminarse a evaluar tiempos de accion concentraciones menores, dispositivos de aplicacion continua, etc. TABLA I - Concentraciones de detergentes anionicos en aguas crudas y tratadas con GIDQX Cone. en detergentes (mg/L) fluestra N Q 1 2 600 300 A las 24 horas 8 4 1 A las 48 horas 8 3.2 1 Tnicial (cruda) 3 30 j mmv+ ii. - » ^ % n — — — — — w x * Ozonocloracion coit produce ion in-siiu UNANUEVATECNICA DE INTERESANTES POSIBILIDADES La provisi6n de agua potable y mas espeefficamente la entrega al usuario de agua segura desde el punto de vista microbi6logico es tin problema que, lejos de estar solucionado, preocupa tanto a los organismos de provisi6n de agua como a las autoridades de la •salud publica. Segun la Organizaci6n Mundial de la Salud, 4 de cada 5 camas en todos los hospitales del mundo estan ocupadas por enfermos relacionados directa o indirectamente con la mala calidad del agua de bebida y/o inadecuada disposici6n de excretas, tornandose este problema mucho mis y numerosas agencies de ayuda internacional han volcado no poaflictivo en las areas rurales y en cos esfuerzos en conseguir tin sisla periferia de las grandes ciudatema lo suficientemente confiades del Tercer Mundo. ble y que hiciera (rente a los inLa causa, estudiada y reconoconvenientes anotados. cida, yace en la falta de equipos En America, la OPS, a travel y m^todos de desin(ecci6n que de un programa de Tecnologfa sean sencillos, durables, confiaApropiadaorientada desde su Ofibles, de facil operaci6n y bajo cina Central en Washington y conmantenimiento, que sean econ6tando con el apoyo del Programa micos y que se indepjendicen del de Naciones Unidas para el Desaproblema de compra\en lugares rrollo (PNUD) ha investigado un alejados (incluida eh casos la imgran numero de alternativas tecportaci6n), transporte y almacen6logicas aplicables a la desinfecnamiento de sustaricias qufmicas cl6n tales como hipocloraci6n, utilizadas en la desinfecci6n. ozoni;aci6n, yoduraci6n, radiaTornado a nivel mundial, la cion UV, asf como la cloraci6n OMS, UNICEF, el CEPIS, el IRC 20 A G U A por gases, elbraminas, resinas.ha,logenadas, di6xido de cloro, etc. Hoy y gracias a este apoyo e iniciativa, parece haberse encon* trado un sistema con las mejores, posibilldades yque responde a las mayores expectativas: la ozonot cloraci6n con producci6n de gases in-situ. Sabido es que la ozonlzac(6rt es una tScnica de excelentes prdpiedades desinfectantes y que el uso del cloro aporta el residual indispensable para hacer (rente a eventuales contamlnaciones ocurridas entre el momento del tratamiento y el del uso del agua. GIDOX, un exponente da esta desinfeccion t^cnica, es un sistema que, en base a agua, aire, electricidad y sal comun (sustancia disponible en cualquier lugar por alejado que est£), produce una mezcla de gases oxidsnles cuyos principales componentes son ozono, per6xido de hidr6geno, cloro y di*6xido de cloro. M£s en detalle, GIDOX es una celda de tipo electrolftico, dividida en dos semiceldas, que descompone !a sal y el agua por el pasaje de electricidad de bajo voltaje comandada por un m6dulo de control electr6nico que acompana al equipo. El proceso electroh'tico produ- Reproducido de ANOXIII-EDICION5Q MAYO DE 1987 ISSN 0325 - 6235 Es una publicacion de: Producciones S.R.L. Emilio Mitre 130 1424 Buenos Aires Tel.: 432-5273 Republics Argentina Registro Nacional de la Propiedad Intelectual N ° 35844 Directoi: , Horacio J. Bacot ce en una semicelda dos subproductos que se descartan: hidr6xido de sodio e hidrogeno; mientras que en la segunda semicelda se genera la mezcla oxidante la cual, conducida a traves de una apropiada conexi6n, es introducida en el circuito del agua a tratar. La instalaci6n es sencilla: junto con el equipo se proveo un venturi que absorbe los gases producidos en la celda y los inyecta en el torrente de agua. Este venturi debe colocarse en la canen'a "principal o en una derivaci6n. La operaci6n s6lo requiere del agregado de sal y agua a la celda cuando sea necesario y la diluci6n del hidr6xido de sodio que se va produciendo a medida que transcurre el proceso. La tasa de generaci6n de gas es comandada por la electrolisis, la que a su vez es controlada variando la corriente el^ctrica que circula mediante el manejo de un dial en el m6dulo de control. (Este m6dulo permite tambten la incorporaci6n de un buzzer para avisar a distancia si la celda carece de agua y, mediante conexi6n a un caudalfmetro, la producci6n da gas segiin demanda de caudal.) La desinfecci6n 6ptima y por lo tanto la dosis ideal se consigue variando la producci6n de gases de forma de obtener en el lugar en que se desee el residual de cloro pretendido, lo que se verifies con el sencillo analisis de la ortoTolidina. Debido a que los gases oxidantes producidos en una unidad N GIDOX se componen aproximadamente de un 7G% de especies deloxi'genoy un 30% de especies del\cloro, se puede esperar obtener los mismos subproductos da desinfecci6n que se obtienen cuando estos desinfectantes se utilizan por separado. Adem^s, el ozono y los radicales libres del oxi'geno reaccionarian con mayor focllldad ante sustancias org^nicas qua el cloro, dando corno resultarfo un nlvel slgniflcativamente monor de trlhalometanos que el que te obtendrfa usando r6lo el cloro. De manera similar, el oxfg«no puede reaccionar con mayor fccllldad que el cloro ante los fenoles y las algas debido a su afinlded por la materia orgaViica, reduclendo con ello los problemas d * $abor y de olor, asf como la formaci6ndecompuestos organoclorados no deseados. Segun la Organizaci6n Panamericana de la S«lud(1) "Desde el punto de vista desalud publica, GIDOX deberfa resultar, por lo menos, tan berwflcloso y seguro como el cloro". Por afiadidura a la soluc!6n de problemas de contaminaci6n microblana, GIDOX tamblSn presenta la poslbilldad de destruir susUnclss oxidables tanto organlcas como Inorg^nicaspresentes en dewgGes cloacales e industriales, con un ventajoso comportamiento frente al cloro, tal como se desprende de experiencias verificadaj en tratarnientos paralelos GIDOX-cloro gasy que se presenIan condensadas en los gr^flcos odjuntos. El rango de apllcaci6n varfa detde el ufo familiar al tratamiento de agua de plantas potabilizadoras de hasta 10.000 habitantes por unidad, a lo que habrS que eumar afluentes y efluentes Industriales, cloacales y piscinas de natacl6n. El equipo GIDOX es producldo en Argentina por FENAR S.A. (1): Mo|ns de Divulgacl6n Te"cnica OPS/CEPIS - N ° 32 - 1986 H O T A : Flguras de este artfeulo en la p^glna slgulente. Trrijsjo preparado por: Injj. Sanit. Felipe Solsona FENAR S.A. Pcywndu 2361 Ducno* Aires Por su gran rendimiento y bajo costo, este equipo es ideal para la desinfecci6n de aguas de uso dom6stico tales como las de viviendas familiares, edificios de departamentos, countries, hospitales, escuelas, piscinas, etc. Debido a que este sistema produce ozono y cloro simultaneamente, se reducen los inconvenientes detectados cuando el cloro es el unico desinfectante, ya que el ozono, con su mayor poder, destruye la materia organica y los amoniacales presentes en el agua cruda, evitando la formacion de cioraminas que otorgan sabor desagradable al agua y de trihalometanos, de probada acci6n cancerigena; permitiendo sin embargo la permanencia del cloro en el agua como prevencion a futuras contaminaciones. La producci6n de este equipo, estimada en 100 gramos de oxidante por dia permite la desinfeccidn de hasta 100 m3 diarios (100 000 litros/dia), lo que da posibilidad de desinfectar TODA el agua de consumo, que incluye la de preparaci6n de alimentos, higiene personal, lavado de ropa, limpieza de ambientes, etc. Este equipo se presenta en dos versiones: GID0X -2A consiste en un generador de gases con su correspondiente inyector y modulo de comando. G1U0X -2B idem al anterior pero con una bomba de recircula\ \cion incorporada. FENAR S. A . Admlnlslraclfin y Veritas: PAYSANDU 2361 Tecnologia TEL. 59-2154 en Aguas (1416) BUENOS AIRES • ARGENTINA Para \a seleccifin c o r r e c t a de un equipo GIDDX -2 se deben c o n o c e r Ires datos f u n d a m e n t a l s : 1. Dosis de gases d e s i n f e c t a n t e s a a g r e g a r 2. Volumen de agua a t r a t a r 3. riempo que debe o p e r a r el equipo 5i bien h n b r i a que e f e c t u a r un analisis qulmico p a r a c o n o c e r c o n exacfcitud cual es la c a r y a de cnntaminacion de un agua ( c a r g a o r g a n i c a o demanda), se puede suponer que para un agua c l a r a prov/eniente de una p e r f o r a t i o n o de un d e p 6 s i t o limpio, la DOSIS de d e s i n f e c t a n t e a a g r e g a r a un agua c r u d a es del o r d e n de 1 mg de o x i d a n t e / l i t r o de agua ( e q u i v a l s a 1 gramo de d e s i n f e c t a n t e / m 3 de agua). G i r o d a t o irnportante a c o n o c e r es el volumen de agua a t r a t a r por dia. Esto es el volumen de TODA el agua que se usara en el e d i f i c i o , e s t a b j e c i m i e n t o , e t c . Con estos dos d a t o s se puede o b t e n e r la c a n t i d a d de d e s i n f e c t a n t e n e c e s a r i o ya que: D031S x VOLUMEN DE AGUA DiARIU = GRAMOS DE DESINFEC. NECESARIO POR DIA Conociendo la c a p a c i d a d de p r o d u c c i o n del G1DOX -2 en gramos de o x i d a n t e / d i a que es igual a 100 gramos/dia 6 100 g/24 Moras, se puede c a l c u l a r el tiempo mecesario que el equipo debera f u n c i o n a r para p r o d u c i r t a l c a n t i d a d : GRAMOS DESINF. POR DIA x 0,?A h/g - MORAS DE FUNCIONAMiENTO DEL EQUIPO Si el agua a t r a t a r c i r c u l a por el i n y e c t o r un tiempo IGUAL o MAYOR que el tiempo establecido en el c a l c u l o a n t e r i o r , se debera usar el GIDOX -2A. En caso de que el agua c i r c u l e un tiempo MENOR que e l e s t a b l e c i d o por el c a l c u l o , se debera usar el GIDOX -2B. Este ultimo equipo viene p r o v i s t o de una pequena bomba i n d e p e n d i e n t e que p e r m i t e el funcionamiento de aquel aun cuando se haya d e t e n i d o la bomba p r i n c i p a l que impulsa e l agua al tanque o a l sistema de d i s t r i b u c i 6 n . El tiempo e x t r a que d e b e r a f u n c i o n a r el equipo se r e g u l a f a c i l m e n t e por medio de un temporizador i n c o r p o r a d o en el modulo de cornando. Al termino de ese tiempo e x t r a , el modulo d e t i e n e a u t o m a t i c a m e n t e t a n t o el f u n c i o n a m i e n t o de la bomba a u x i l i a r como el del equipo. EJEMPLO: Supongamos que se deba t r a t a r un tanque de agua de un e d i f i c i o de d e p a r t a m e n t o s de 10 m \ el cual t i e n e una bomba que lo llena en 2 h o r a s . El t a n q u e es llenado 2 veces por dia. VOLUMEN DE AGUA D1ARIO A TRATAR= 10 m3 x 2 = 20 m3 DOSIS \ = 1 g desinfectante/m3 GRAMOS DESINFEC. NECESARUDS POR DIA = 20 m3 x 1 g/m 3 - 20 gramos HORAS FUNCIONAMIENTO BOMBA PRINCIPAL = 2 h o r a s x 2 v e c e s / d i a = 4 h o r a s / d i a HORAS FUNCIONAMIENTO DEL EQUIPO = 20 g x G,?U h s / g = *.,8 h o r a s Dado que el v a l o r n e c e s a r i o de tiempo de f u n c i o n a m i e n t o del GIDOX-2 supera al tiempo de funcionamiento de la bomba^se debe usar e n t o n c e s e l GIDOX - 2B. F E N A R S. A. _ - Administraci6n y Ventas: PAYSANDU 2361 T e c n o l o g i a TEL. 59-2154 e n A g u a s (1416) BUENOS AIRES ARGENTINA **TNP^ C R I T E R I O R/XR/X S E L E C C I O N A R E Q U I P O S G 1 D O X 1F>/\Fi/\ N A T A T O R I O S Para la seleccion de los equipos G1DDX a ser usados en n a t a t o r i o s se deben t e n e r en c u e n t a f a c t o r e s tales como: 1) volurnen de ia piscina, 2) t i p o de agua, carga de bafiistas, exposici6n a rayos del sol y polvo o t i e r r a y 3) horas de r e c i r c u l a c i o n del equipo f i l t r a n t e . En el punto 2) se toman t r e s tipos de n a t a t o r i o s , cada uno con una c a n t i d a d de o x i d a n t e a dosificar segun e l s i g u i e n t e c r i t e r i o . Dosis = 1 g/m 3 de o x i d a n t e : Dosis = 2 g/m 3 de o x i d a n t e : Dosis = 5 g/m 3 de o x i d a n t e : N a t a r i o s con agua en buen estado y buen sistema de f i l t r a c i 6 n . Con poca c a r g a de baftistas, poca exposici6n a polvo o t i e r r a y con p a r t e del dia b a j o sombra. N a t a t o r i o s con c a r a c t e r i s t i c a s intermedias N a t a t o r i o s con a l t a c a r g a de bafiistas, exposici6n a polvo o t i e r r a y t o d o el dia b a j o s o l . Volurnen n a t a t o r i o = 25 m3 HORAS DE RECIRCULACION U 1 en tn o Q 8 12 2U G-5 G-2 G-2 G-2 2 G-10 G-5 G-2 G-2 5 G-30 G-10 G-10 G-5 8 12 2U 1 G-10 G-5 G-2 G-2 2 G-15 G-10 G-5 5 2xG-30 G-30 G-15 5 G-5 G-2 G-30 G-10 R-S G-30 G-15 2 ZxG-30 G-10 5 4xG-30 2xG-30 Volurnen = 500 m3 X « 2xG-30 G-30 G-10 2 G-30 5 FENAR G-10' G-2 G-10 4xG-30 2xG-30 2*. G-30 G-30 ftxG-30 12 1 A 2 D C? 8 12 2xG-30 Q. U Volurnen = 200 m3 1 O Volurnen = 100 m3 U 8 Ct CD Volurnen = 50 m 3 U X a' \ S. A . ESTOMBA 1949 Admlnlstracidn y Veritas: PAYSANDU 2361 U 1 T e c n o l o g i a TEL. S9-2154 8 AxG-30 2xG-30 12 24 G-30 G-15 AxG-30 2xG-30 G-30 3xG-30 en A g u a s (1416) BUENOS AIRES ARGENTINA GIDOX EIM I_,/\ I N D U S T R I A Uno de los graves problemas que enfrenta la Humanidad en la actualidad es la contaminaci6n del medio ambiente. En particular, la contaminaci6n de las aguas es un hecho que preocupa a las autoridades de los paises por su magnitud y el origen de sus causas. Entre estas ultimas pueden citarse: = Falta de legislaci6n apropiada y dificultad en la aplicaci6n de la misma. = Desconocimiento y/o desinteres en aportar medidas de solucion por parte de los industriales. = Falta de equipos o sistemas econ6micos, de bajo costo de operacidn y mantenimiento y sencillez de funcionamiento compatibles con los costos industriales. Sin pretender ser la soluci6n total de cualquier problema de efluentes, el sistema GIDOX aporta una notable sencillez de uso a la vez que una excelente capacidad de tratamiento en todo desague industrial que requiera una oxidaci6n energica y que este compuesto por cianuros, fenoles, amoniacales, organicos en general, detergentes, herbicidas, plaguicidas, inorganicos oxidables, materiales pat6genos, etc. Por sus bondades y costos tanto de adquisici6n como de operaci6n, GIDOX es el mas adecuado para su uso en toda industria con efluentes liquidos de alto riesgo. \ F E N A R S. A . - Admlnlstracldn y Ventaa: PAYSANDU 2361 T.ecnologia TEL. 59-2154 en Aguas (1416) BUENOS AIRES ARGENTINA G 1 D D X A V E1L / \ G U / \ P O T A B l . e7^ Segun la Grgani/aci6n Mundial de la Salud, en la actualidad 0 de cada 10 camns on tndos Ios bospitales del inundo estan ocupadas por enfermos relacionados directa a indirectamonte con el agua que consumers IMuestro pais no es una excepcion, y en la moyoria de Jas areas rurales, la principal causa do mnrbi-mortalidad infantil es la diarrea y las infecciones gastrointestinales de oriyen hidrico. I7xist.cn leyus y normas que precisan la necesidad de la desinfecci6n de las aguas que se enlregan a la poblacion, pero ellas no se cumplen debido principalmente a una serie de faclores entre los que figuran: = Falta de conocimiento de los niveles de decision pulitica de la magnitud totalidad y complejidad del problema. - Falla en reconocer el riesgo sanitario por parte de la poblacitin. = Falta de equipos de desinfeccion en plantas potabilizadoras que cumplan con: Costo reducido de inversion Dosto reducido de operacion Sencillez de operacion y mantenimiento Independencia de la compra, traslado y almacenamiento de peligrosas sustancias quimicas FFMAR 5A. una empresa argentina cuyos profesionales, consul tores de organizaciones de salud internacionales que conocen el problema y In han estudiado tanto en sus causas coino en sus soluciones, presenta la linea G1D0.X, equipos de ozono-cloracion con produccion de gases in-situ, que cumple con la totalidad de los requisitos de un equipo de desinfeccion ideal y que son los anotados precedentemente. Porque G1DOX es algo mas que un equipo de desinfeccion. Fs un sistema que garantiza la caliriad del agua que se entreya a la poblacion no solo por las sust.ancios alt.amente desinfectantes que genera, sino pur la suma de virtudes que hacen a la operacion y manejo del equipo v en forma especial al heeho de no requerir del auxilio de compuestos quimicos costosos y peligrosos de manejar. Tan solo electri cidad, aqua y sal comun. Es por ello que la Organizaeion Panamericana de la Salud ba expresado publicamente su apoyo a este sistema, y es su esperanza que aquellos que tienen poder de decision en la adquisicion y/o uso de estos equipos oigan el llamado y coadyuven para solucionar uno de los grandes problemas de la Humanidad. que no por antiguo deja de ser menos angustiante y grave. F E N A R S. A. T e c n o l o g i a en A g u a s (1416) B U E N O S AIRES A d m i n i s l r a c i b n y Veritas: P A Y S A N D U 2361 TEL. 59-2154 ARGENTINA M O D U L Q S *££** DIE C D N A N D O Los modules de comando de los equipos GIDOX para ozonocloraclon de aguas, tienen por obJGto controlar la c o r r i e n t e que circula por las celdas e l e c t r o l i t i c a s , gobernando asl la producci6n de las mismas. Los distintos tipos de modelos disponibles, permiten tambien el acceso a una serie de funciones auxiliares. Los equipos standard van alimentados con tensi6n de red, corrlen te alterna, de 220 V 6 110 V segun pedido, pudiendo suminlstrarse mOdulos especiales que funcionen con o t r o tipo de alimentaci6n. El MODULO C-1 es una fuente de alimentaci6n con dos valores fijos de corriente (100 % y 50 %), que corresponden a la producci6n maxima nominal del equipo v a su mitad. Estos modulos son aptos para instalaciones donde no se requiera un ajuste exacto de la producci6n, pudiendo regularse la dosificacion ya sea controlando el tiempo de funcionamiento del equipo, o bien el caudal de agua. Tambien sirve para el caso en que esten operando en paralelo mas de un equipo, donde algunos son de valor f i j o (usan el modulo C-1) y otros son de ajuste (usan modulo C-2 6 C-3). C-1 GIDOX • • o* • 9 it *(*?-•-«, -*-_ El MODULO C-2 permite el control continuo de la corriente, pudiendo de esa forma ajustarse la dosificacion desde cero hasta el valor maximo nominal. Debido al tipo de sistema de control, este es muy apto para instalaoiones en las que las variaciones de tensi6n de linea sean muy amplias. C 2 GIDOX 9 El MODULO C-3, que tambien controla desde el cero al 100 %, es un acabado sisterna de control electrfinico, ID que le confiere una gran solidez mecanica y larga vida util. Tiene un display a leds, lo que permite una rapiria \/isualizaci6n del estado del equipo. Con el objeto de acelerar la entrada en regimen inicial, cuenta con un subsistema de sobrealimentaci6n electrica. Informa la f a l t a de nivel de agua en la celda tanto visual (luz) como con alarma sunica buzzer- (opcional). Asimismo posee un sistema realimentado que estabiliza la corriente al valor deseado f r e n t e a variaciones de parametros externos. Admite variaciones de tensifin de linea de liasta el 20 % y cuenta con la posibilidad de dosificar segun demanda de caudal (opcional). FENAR S. A. Aominlstracidn y Venlas: PAYSANOU 2361 Tecnologia TEL. 59-2154 t S3 en Aguas (1416) BUENOS AIRES ARGENTINA *£sr** :ELECCION SEGUN IPARA PE EQUIPQS CAUDAL, AGUA A TRAT7AR POTABLE HAST A CAUDAL, 3 C m /Y\ ^ FENAR GLDOK MODEJL.O 4 G- 2 8 G - S i e> G- 1O 23 G- 1.5 4 5 G - 3 0 S. A . ESTOMBA 1949 Adminlstraci6n y Ventas: PAYSANDU 2361 Tecnologia TEL. 59-2154 en Aguas (1416) BUENOS AIRES ARGENTINA Il\J5T/M_/\c:iOf\) ^ " N P ^ H I D R A U L I C A INYECTOR FLUJD PRINCIPAL _ D E L D I 5 E N O t G I D O X NYECTOR B A S I C O Es la i n s t a l a c i o n basica y es ideal para t u b e r i a s de bajo diametro y donde no c i r c u l e demasiado c a u d a l . V/A'LVULA DE REGULAC1GIM INYECTOR MODULO DE CONTROL £ FLUJG PRINCIPAL W&2 VALVULA REDUCrORA Este esquema es ideal cuando no se der.ee una p e r d i d a de c a r g a muy grande y cuando la t u b e r i a p r i n c i p a l sea de diametro pequeno Esta c o n f i g u r a c i 6 n puede usarse cuando la t u b e r i a p r i n c i p a l es de diametro g r a n d e . La deriv/aci6n se debe armar a l r e d e d o r de una v o l v u l a e x i s t e n t e y en caso de que no la hubiere, se debera i n t e r c a l a r una. BOMBA AUXIL1AR BOMBA El uso de una bomba a u x i l i a r p e r m i t e independizarse del sistema evn donde se i n y e c t a , y t i e n e la v e n t a j a de p o s i b i l i t a r t a n t o la r e i n y e c c i o n de agua con los gases en la misma\tuberia como en un tanque o c a n a l . _ \ F E N A R S. A. Esta configuracion es excelente cuando se tiene facil acceso a una bomba impulsora instalada en el sistema. T e c n o l o g i a en A g u a s (1416) B U E N O S A d m i n i s t r a c i o n y V e n t a s : P A Y S A N D U 2361 TEL. 59-2154 AIRES ARGENTINA .deeinfeccion. MODIFICACION POR ACCION DEL GIDOX APUCADO A UN EFLUENTE INDUSTRIAL CONTAMINADO 8000 1.0 a@ 0.6 400 0.0 A 300 Q 160 4 A 300 200 100 o—__ (poi) > 0.1 \D \ZJ I . A B 0 V - / o • 600 A —X B A 40 30 20 o 0 • 1 8 O 760 \ 260 A = :°v (=) \\ ^ \ 10 0.0 B 400 -o A 0.2 (Na) 0 2 A 400 - B A 800 3 o o B 0 B = b i , l.. B Aaua Crud« Agu» tratad* corj GIDOX (V*tor«s «n «ng/|, •xc«pto par* pH) ANALISIS COMPARATIVO DEL TRATAMIENTO CON CLORO GAS Y CON "GIDOX" A UN MISMO EFLUENTE CLOACAL KG DE OXIOANT6 POR DIA 28* MEMOS ilii»i»'i<f"l. 1 1.16 CLOPO LIBHE HESIDUAU COLI FECALES EN 100 ml «•> s ^ W - i t°3 20 E 7 ^ — 1"F-T?T3 6.1 OXIGENO DISUELTO -^T 6.1 I 33% MENOS 6% MAS PH I 1 87% MENOS 6% MEJOH CLORO GAS * 24 AGUA lA~ 1 P L A N T A S C O N P A C T A S R C R - 1 P O T A B I L I ^ A D O R A S P C P - 5 La PCP es una linea de equipos maduiares, con capacidades de procfucci6n de hasta 5 mJ de agua potabilizada/hora. El tratamiento del llquido se produce segun la secuencla tradiciooal de ingreso-dosificaci6n de coagulante-floculaci6n-decantaci6n-filtraci6n-desinfecci6n. Sin embargo, la modificaci6n de algunos parametros y la adopci6n de nuevos equipos permiten en las PCP las mejores calidades fisico-qulmicas y bacterlol6gicas en el agua efluente a la v/ez que un reducido espacio ocupado. Si se parte de aguas superficiales con elevados tenores de turbieried 1 slstema de ranoci6n de la misma a p a r t i r del uso de coagulantes comunes y da un decantador de f l u j o horizontal ascendente con ssdiplacas incorporada3, SB o f e c t u a con altfstma gficiencia obteniundose un producto limpio y cristalino. Si el agua en cambio es dura o salina, el equlpo permite la incorporaci6n, siempre dentro del esquema general, de un ablandador o de un desmineralizador, los que actuando bajo la tecnica del intercambio ionico eliminan la carga salina. El ablandador o el desmineralizador son optativos. La f i l t r a c i 6 n , o t r a importante etapa del tratamiento, se realiza en un f i l t r o de grava y arenas sillceas, pero si el caso lp requiriera, se puede incorporar al mismo una capa de carbon activado lo que eliminaria tambien cualquier problema de gusto u olor. La etapa final del tratamiento, la desinfecci6n, se realiza con el euxilio de un equipo GIDOX, celda productora de ozono y cloro a p a r t i r de agua y sal comun de mesa. Tal mezcla oxidante garantiza no solo un sabor agradable en el agua, sino y muy especlalmen te la completa y segura ausencia de germenes patogenos. Pueden resumirse las caracteristicas de las PCP asegurando qua se t r a t a de los mas compactos, seguros, simples de operar y mantener, econ6micos y de a l t a performance sistemas productores de agua potable, ideales para el medio r u r a l , o para grupo de viviendas, pequeftas poblaciones, escuelas, puestos sanitarios, hospitales, obradores, clubes, countries, fabricas, y aun como plantas mdviles para casos de c a t a s t r o f e , inunda ci6n, etc. FEfMAR S. A. - ESTOMBA 1949 Adminlstrncldn y Vontas: PAYSANOU 2361 T e c n o l o g i a TEL. 59-2154 e n A g u a s (1416) BUENOS AIRES ARGENTINA * • $ * * * C A R A C T E R 1 S T I C A S D E C O I M S T I T U I l V a S L O S D E E L E M E I M I L/^XS O S P C P DOSIPICADOR UE CUAGULANIE !li! train tlnm depftnfto da poitettleiKi, con r e g u l a t i o n jmr volvula I n f e r i o r y rior.irii-_->ciOn n notoipnr Inycnciftrt en la roplreclftn da la Uombe, lo que f f l c i l l t a l a homoo/jima y p e c f n e t a dwer3l6n del coagulants empleado. FLOCUI.ADUU. Va occiorv.tmiraif.o lildi-.'mtlcoi i» rmrmlto vnlocidadns docr<?clenl;nD, lo quo fovorr.Mrn Jo ConiiaciOn 1J1? co'iqii/im Uifl •iioAirj nnrorlndas pots la decantaclon. El floculndar RSt5 inketjiado ol sintpitvi tta iladnr/docontodur. DECANIALXIH. Ponoc m m rainara coiiipnurxidbra para distribuciou lominor del Tlujn do lurjryyo. Cuonfca c n n placas nspr'cialns iiicUKJ.m en un 'mijulo picCljodo porn obteiiRr por una p a r t e Id mayor to->o du inloi catnlfcn ptir cnnslguiente dc srtfinientocIGn ds las particular, do ttirhiedad, y por ohra, u a w r i c i o n t o arclOn da eutolltnpiaza, lo qua f o c l l l t n ;IIJ titlll/nclOn. F l l l i n i . Do I'tinr/o t'n rltm grout iluini?tr1nn tlfcrnMl.ni: r o n coltint.or p|/mUcrt rfo nltp inipaclu; esroros riltroittnn roiuir.ida:) do tXmw do posaje, con munftinetro Incoiporodo y ptii'un do a i m . AHIANPAPIJN/DESMINEHALMAOUH. Ai:l.i'/,i IjajM'l r r i n e i p i u dnl intc»ir.nmtilo I6I>ICO. con I esin.-ir; i>:;('i?i:Joi7-n"r;h"rf.<>i.k:.-r: • itit! ptirmltmiB pliinlnaclftn do In col H U sollno. Ento oqulpo es o p l a t l v o , si nl caso lo ri'qiiirioia. OEUINrtiCCIUN. l o (losinr»;t:i;lfin i.'sl.i'j prci/i-Jk, pin- lo occiori cle un equlpo 15IDUX: :;l!itnma unico en r,u ij&nom v aconnnjailo por In Uigrtl/arAOn Mundial de lo fialud. r i u d u c e oiunu y e l m o a p . i r t i r do .njuo v '.'»"»l comi'mli? «M;-;;I. l o mezclo tie gasoa oxldanfcps genurada pur pi r?qi;ipn ir.-.ugvrn lo t o t a l <>Vm\wMn\ du bacterleg potOgenns en ol ogua eTIuente ds la p l a n l a . IJUMIJA. Dp tipo conlriftujo. horizontal t'n iwul'lock. Segun r«queriinionto SB proves en'Ye, ?m 0 3(10 Voltr., 50 llz. EUAOHU 01: VAIVUlAr, V SISIEMA Of INICHtHEXIUN. IudjiS Inn r.nHmlog. nccnnnrloD y valvular; r.nii do I ' V C G dp Pulipnipiiono y s a r c s e n t a n en cuadios ds nianlobra do facil vir.uoli/oeion y accionamimitu. CAiiA(;n:m'.iiii:An CUN:;imH:iIV/AS UPL riufJiAOU'VDEL'ANiAoon. FILIIU) V AHLA^DADOR/ O E S M I N ' I - H A U Z A U U H . LOIS eliMiirntcia iminciiHin* pr.t.'m todos conrBCClo:iado3 en cliopa tie ticeru ill c.irlnifiti 1D1II/10?!), con c.'ilH'/otattnrlpr.ffnicos con Urldnn elmlottodns , y Irotndno con rpnliiiit: upoxi p i e v i o a i - n n o * v ronliitlj.ndo; lo qu» 3r,G<juro una muy l.ircj.-: v/dn n lnr. plnnUw a lo voz quo una i * / a d n rohuslaz y roalstencln a foa onnntng internns v i»xl:srnus. Todo i?l conjunliri ^t» pio:;i;nta inont.aiki r n tirfiinrjo lo quo pomilte su f6cll ublcnclftn d e f i n l t i u a 6 cl tror.l.ido Din npcesldod i)o dowirnl ft pordlda da tlempo. CAUDAL nooccq PCP-1 PCP-5 1 5 I):M'.:NUIIINI:'.; at Lajruu A u d i o Allan 1.50 1.UU 0.'.5 11.110 Voclo 1* IX. r^corpa En t r a l i o j o 55 110 Z50 U5 230 950 * c o n cblandodor incluldu FENAR S. A. E S T O M B A 1949 Adminlslracl6n y V e n l a s : P A Y S A N O U 2361 Tecnologia TEL. 59-2154 en Aguas ( I 4 I 6 J 8 U E N O S AIRES ARGENTINA *fer*efr < »- u < D. 1 0 j u< c < Ui c z • 0 UJ 0 0 < N < M J M I « (D Q: < ID 1- < 0 0 a < h z < _i a FENAR S. A . ESTOMBA 1949 AdmlnlElrccldn y Vcntaa: PAYSANDU 2361 Tecnologia TEL. 59-2154 en Aguas (1416) BUENOS AIRES ARGENTINA ^sKT^ P L A N T A D E P U R A D O R A MSCKIPCION Planta depuradora que a traves de un tratamiento integral del liquido cJoacal. permite obtener un efluente cuyas caracteristicas de alta limpieza, baja DBO y ausencia de germenes pat6genos, es facilmente disponible en cualquier curso o terreno. La planta cuenta con secciones que aunque individuates estan integral s en un todo, haciendo a la misrna facil de operar y mantener a traves de una total automatizaci6n.. ELEHENtOS CONSTJTUYENTES La planta cuenta con los siguientes elementos de acuerdo al camino que recorre el liquido a tratar: - Camara de entrada del liquido cloacal - Concentrador de s61idos por reja manual o automatics - Camara de bombeo - Difusor presurizado - Sedimentador primario - Turboeyector - Primera camara de barros activados - Canaleta de eliminacidn de espumas y recirculacion - Segunda camara de barros activados - Dispersor de coagulante - Floculador - Sedimentador secundario - Filtro - Desinfecci6n por ozono-cloracion FENAR S. A. Tecnologia en Aguas (1416) BUENOS AIRES Adminlstracidn y Veritas: PAYSANDU 2361 TEL. 69-2154 ARGENTINA VyEEPsiT/^JAS S Q B R E EfM EEL P E L L O S S I S T E M A FEEiM/O^R OOF\J\/tE[\]C:iOt\J/^\L.EES T R A T A M I E N T O DEE C L O A C A L E S "feN** SISTEMA COIWEIMCIONAL SISTEMA FENAR ESPAC10 REQUERIDO l a s p l a n t a s de t r a t a m i e n t o de e f l u e n t e s convencionales f u e r o n diseft3das t r a t a n d o de l o g r a r capacidades y espejos de agua i m p o r t a n t e s para o b t e n e r mejores o x i g e n a c i o n e s y tiempos de permanencia h a s t a Uegar a la d e g r a d a c i 6 n bioJ6gica por medio de f l o r a a e r 6 b i c a . Esto demanda obras c i v i l e s de e n v e r g a d u r a c o n el c o n s i g u i e n l e gasto de e s p a c i o . Las obras c i v i l e s r e q u e r i d a s p o r n u e s t r o sistema de d e p u r a c i 6 n se r e d u c e n a una p l a t a f o r m a de apoyo p o r los estanques m e t a l i c o s mas dos camaras de r e c e p c i 6 n de Ifquidos. Corno ejemplo: p a r a una p o b l a c i 6 n que c o n un sistema c o n v e n c i o n a l r e q u i e r a 400 m*. el sistema FEIMAR solo n e c e s i t a 160 m 2 . COSTOS Los c o s t o s de e s t a i n f r a e s t r u c t u r a son realment.e elevados debido a los e s t u d i o s de suelo p r e v i o s a la c o n s t r u c c i 6 n , e v a c u a c i o n de aguas s u r g e n t e s donde las h u b i e r e ; basamento p a r a las misrnas y costos de la o b r a e s t r u c t u r a l . Los costos de i n f r a e s t r u c t u r a son r e d u c i dos pues no r e q u i e r e n basamento ni espa cios i m p o r t a n t e s . TIEMPO DE EJECUCiGIM DE LA OBRA Los tiempos de e j e c u c i o n de o b r a son a p r e c i a bles aun para empresas de a l t a c a p a c i d a d tecnica. Los tiempos de e j e c u c i f i n de o b r a se r e d u c e n notablemente pues los estanques metalicos estan c o n f o n n a d o s p o r paneles plegados p r e f a b r i c a d o s , los que son de muy f a c i l montaje en e l l u g a r de la obra. COINJSUMO DE EIMERGIA Elementos e l e c t r o m e c a n i c o s de g r a n peso, c o n s t r u c c i o n e s r u d i m e n t a r i a s c o n g r a n d e s insumos de energia. FENAR S. A . Adminlstraci6n y Veritas: PAYSANDU 2361 Los elementos e l e c t r o m e c a n i c o s ( a e r e a d o r e s , c o n c e n t r a d o r e s , motobornbas) son de reducido tamafto y f a b r i c a d o s c o n t e c n o l o g i a de p r e c i s i o n , siendo el c o n s u mo de energia e l e c t r i c a r e q u e r i d o , un t e r c i o de los sistemas c o n v e n c i o n a l e s T e c n o l o g i a TEL. 59-2154 e n A g u a s (1416) BUENOS AIRES ARGENTINA £"N^ EQU I IPOS BOMBAS De eje vertical o sumergibles segun el caso. De baja presion, alto caudal y rotores semiabiertos pf.ra evitar obstrucciones. DIFUSOR PRESURIZADO De accion descendente que permite una rapida y efectiva mezcla del liquido ingresante con los barros activados. TURBOEYECTORES De diseflo especial, permiten el desmenuzamiento veloz de los s61idos organicos para facilitar su degradaci6n, a la vez que incorpora grandes masas de oxigeno al liquido cloacal. DISPERSOR A motor con eje vertical y 3 vueltas por minuto. Con dosificaci6n del floculante por medio de un conducto eje-central. SEDIMENTADQR De bajo volumen y alta capacidad debido a la disposici6n de sediplacas oblicuas. FILTRO Abierto de grava y arena; con lavado realizado como en los filtros rapidos convencionales. OZONOCLORADOR Celda GIDOX para dosificacion de gases oxidantes compuestos por ozono y cloro, lo que permite un ajuste fino del proceso oxidante, a la vez que asegura la eliminacion completa de los germenes pat6genos. Hasta 30 m 3 /h se presentan plantas confeccionadas en hierrorplegado, lo que simplifica la instalaci6n y reduce los costos de inversion inicial. Para caudales mayores se confeccionan modulos en H Q A Q y mamposteria. CONSUMO SINHIRGETX OO Hasta 30 m /h aproximadamente 1 HP/m3 t r a t a d o . 3 CZ\TP/\C 1 D/\E>ES 3 Desde 5 m /dia en mas. F E N A R S. A. - Administrecidn y Veritas: PAYSANDU 2361 Tecnologia TEL. 59-2154 en A g u a s (1416) BUENOS AIRES ARGENTINA P L A N T A *«£** f . . 3. t*. 5. 6. 7. 8. 9. 10. 11. 13. lb. 15. 16. 17. 18. 19. 20. f 23. 2i*. 75. 26. 27. DEE D E P U R A D O R A L i q u i D O S C L O A C A L E S Camara de e n t r a d a del e f l u e n t g C o n c e n t r a d o r de solidos Camara de bombeo Bombas D i f u s o r presurizado Sedimentador p r i m a r i o Turboeyector Primera e t a p a de o x i d a c i 6 n Retorno de solidos flotanUas Conducto r e t o r n o de Pescadores Segunda etapa de o x i d a c i u n Turboeyector Turboeyector T e r c e r a e t a p a de o x i d a c i 6 n Conducto al floculador Floculador Camara de f l o c u l a d o Bomba p a r a solidos sedimentados Sedimentador secundario F i l t r o de g r a v a y a r e n a C o l e c t o r de lodos y c o n t r a l a w a d o Bomba p a r a lavado del f i l t r o Ozono-clorador L a b e r i n t o mezcla d e s i n f e c t a n t e Camara de ludos Camara de salida y tomamuestras FENAR S. A . Administracidn y Veritas: PAYSANDU 2361 T e c n o l o g i a TEL. 59-2154 en A g u a s (1416) BUENOS AIRES ARGENTINA '• • ft * E V A L L J A C I D N B / \ E : T E R I E : I 0 / \ 3 0 B R E P R A C T I C A O E U/\ /\G3LJ/\ OfcEL, R O P E R G Z O N O C L n R A C I O M G A S I F I C A D A Dr. Omar J. Simoni Buenos Aires, Argentina, octubre de 1987 t£\//\t-U/\C:iLJr\] B A C T E R I C I D A S O R R E P R A C T ' I C A PEE L/\ /M3LJ/X PEEL P D D E R O Z O M O C L O R A G I O N G A S I F I C A D A Dr. OMAR J. SIMOMI - D i r e c t o r del ECCA - Estudio Cnnsultor en Contaminacion Ambiental, M a t u r i n 2887, Buenos Aires, A r g e n t i n a - Asesor l e c n i c o de la Federacion A r g e n t i n a de Aguas Gaseosas y Rebidas sin Alcohol. - D i r e c t o r Tecnico de C1MES - C o n t r o l I n t e g r a l Metodologico de Sodas, A r g e n t i n a SUMMARY This work is r e l a t e d t o t h e evaluation o f t h e d i s i n f e c t i n g power o f a GIDQX ozonoc h l o r i n a t i o n c e l l , in a series o f gasified w a t e r b u t t l e s c o n t a i n i n g Feacal Coliform and Pseudomona Aeruginosa b a c t e r i a c u l t u r e s . From the f i n a l e v a l u a t i o n i t can be concluded t h a t t h e experience p r o v e d t o be e f f e c t i v e f o r complete immediate removal o f F.C. and complete P.A. elimination a f t e r ?k hours of t r e a t m e n t , when using water highly c o n t a m i n a t e d . INi'RQDUCCION El t r a b a j o consiste en la evaluacion b a c t e r i o l o g i e s para o b t e n e r el poder b a c t e r i c i d a de la ozonocloraci6n, cuando e s t a se aplica i n - s i t u sobre envases con agua gasificada -sifones- en lineas de t r a b a j o , actuandn sobre la produccion riirecta, previamente cont.aminada con copas de Coliformes Fecales y de Pseudomonas Aeruginosas; con mediciones de o x i d a n t e . Para el estudio se c o n t o con un equipo GIDOX-10 producido por la firma FENAR S.A. de Argentina y la c o l a b o r a c i o n de la Soderia LA MARINA, Andres A r g i b e l Z86G, Buenos Aires, que brindo sus i n s t a l a c i o n e s . r-*. TECINJICA DE EVALUACION Se dispuso de 17 env/ases limpios y sa procedifin a su desarme manual, inoculandose en cada uno de ellos 50 ml dG un c u l t i v o r i c o en Coliformes Fecales v 50 ml d e o t r o cuitiv/o r i c o en Pseudomona Aeruginosa, preparados segun las teenicas b a c t e r i o l o g i c a s c o r r i e n t e s de aislamiento de cepas, con p o s t e r i o r eniiquecimiento. Los env/ases, p e r f e c t a m e n t e individualizados del 1 a l 15 se colocaron en la linea de t r a b a j o usual, r e t i r a n d o s e los numeros 16 v 17 para s e r v i r como t e s t i g o s . El agua de llenado de los sifones, fue la u t i l i z a d a en la operacitin d i a r i a y que s u f r e el t r a t a m i e n t o de pasaje a trav/es de un f i l t r o de arena y o t r o de c a r b o n a c t i v a r i o ; con el agregado en la ocasion de la prueba de los gases oxidantes producidos por e l equipo GIDOX; los que f u e r c n i n y e c t a d o s en el e f l u e n t e del ultimo de los f i l t r o s , antes de un pequefio tanque pulmon, con tiemp6 de permanencia de 5 minutos. Del tanque por t u b e r i a de 1V' y l o n g i t u d e 7 metros el agua es conducida a las maquinas carbonatadora y llenadora. Los sifones f u e r o n llenados segun la operaci6n normal de t r a b a j o , e f e c t u a n d o s e un dosaje de c l o r n lihre en el c o n d u c t o mencionado, v e r i f i c a n d o s e en mediciuncs c o n s t a n t s el v a l o r de U mg/1. Una v/ez en el l a b o r a t o r i o del ECCA se llenaron los env/ases 16 y 17 con agua e s t e r i l y j u n t o con las muestras de la prueba Fueron analizadas bacteriologicamente por el rnetndo de la membrana f i l t r a n t e , segun la t e c n i c a del Standard Methods f o r the Examination o f Water and Wastewater, 16th Ed. KESUUADas Los resultados mostraron ausencia t o t a l de Coliformes Fecales en todas las muestras y solamente uno de los env/ases acuso una c u e n t a para Pseudomona Aeruginosa (v/er Tabla 1). Por esta razon y luego de 24 horas de reposo a t e m p e r a t u r a ambiente, se p r o c e d i 6 a realizar un nuevo dosaje de c l o r o y se r e p i t i 6 el analisis b a c t e r i o l 6 g i c o de la muestra M° 11, obteniendose en e s t e segundo analisis los siguientes r e s u l t a d o s : Cloro residual Pseud. Aeruginosa menor que 0.? mg/1 0 t:0i\O.USIQI\JES Los analisis evaluados permiten v e r i f i c a r -para los ensayos reaiizados- la e f i c i e n c i a b a c t e r i c i d a del ozonoclorador GIDCIX cuando utilizado en aguas de bebida gasificada. Buenos A i r e s , A r g e n t i n a , o c t u b r c de 1987. - \ V ¥ TABLA 1. Resultados de los analisis e f c c t u a d o s MUESTRA N? COLIFECALES (b/IOOml) PSEU. AERUG. CLORO RESIDUAL (b/100ml) (mn/1) 1 0 0 0.5 2 0 0 0.5 3 0 0 0.5 U 0 0 0.5 5 0 0 0.5 6 0 0 0.5 7 0 0 0.5 8 0 0 0.5 9 0 0 0.7 10 0 0 1.2 11 0 IU 0.6 12 0 0 0.5 13 0 0 0.3 U 0 0 0.5 15 0 0 0.5 16 IncontablGS IncontablGS - 17 Incontables Incontables _ 4 , MANUAL DE OPERACTONES Y MANimiMIENTO PARA. FJ. MOGGOD Agost.o d e 1987 * • INBICE Seccion Pagina INTRODUCTION 1 ANITXEDENTES - FUNCIONAMIH<JTO DE LA UNI DAD 2 GENERATOR DE DESINFECTANIE 3 I. II. III. COSTADO DEL ANODO 4 COSTADO DEL CATODO 5 LA MEMBRANA 6 5EGURIDAD MATERIALES NECESARIOS LISTA DE VERIFICACION PARA OPERACTONES Y MAFITENIMIENTO '. 7 8 10 COMO LLEVAR A CABO LA PRUEBA DEL HIDROMETRO 13 LIMPIEZA MENSUAL 15 PUESTA EN FUNCIONAMIENTO 25 REPARACION DEL GENERATOR DE DESINFECTANTE 29 REPAPACION DE DESPERFECTOS 30 GRAFICA DE LA REPARACION DE DESPERFECTOS 32 CAMBIO DE FUSIBLE EN EL \ REGULATOR DE POTENCIA 34 REEMPLAZO DE LA MEMBRANA 35 REEMPLAZO DE LAS BARRAS DEL ANODO Y CATODO 37 AI^IACENAMIENTO 41 POSIBLES UTILIZACIONES DEL EXCEDENTE DE HIDROXIDO DE SODIO 42 INTRODUCTION El proposito de este manual es ayudarle a operar la unidad MOGGOD (Gases oxidantes mezclados gcnerados insitus) y mantenerla en buen funcionamiento por medio de actividades de mantentmiento regulares y reparaciones basicas. El mantenimiento regular le permitira mantener un nivel de desinfectante apropiado en su sistema hidrico, para poder alcanzar los mayores beneficios de salubridad. Este manual esta basado en la unidad 0X1 de dos libras (un kilogramo), que en la actualidad es el modelo MOGGOD mas comunmente disponible y ampliamente utilizado. Hay cuatro tamanos diferentes de las unidades MOGGOD disponibles. Cada unidad puede desinfectar los sistemas hidricos que benefician hasta 20.000 personas. \ 1 ANTBCECSEN'T'fcS FUNCIONAMIEWIO DE LA UNIDAD El sistema desinfectante de MOGGOD tiene tres componentes principales: 1. Regulador de potencia - controla la cantidad del flujo de electricidad a traves del generador de desinfectante. 2. El generador de desinfectante - produce los gases desinfectantes. 3. El tubo de Venturi - conecta al generador de desinfectante con la fuente de agua y crea un vacio que absorbe los gases desinfectantes hacia la fuente de agua. «fi&** Regulador dfoi de potenciaN Generador de des in fectante Tubo de Venturi El sis tenia de ICiGGOD simplemente convierte una solucion saturada de agua salada en una mezcla de gases desinfectantes poderosos mediante el uso de la electricidad. El regulador de potencia controla la proporcion (cantidad) de desinfectante producido, para rnedir con exactitud las necesidades de desinfectante del sistema hidrico. El tubo de Venturi se utiliza para inyectar la mezcla de gases desinfectantes en el sistema hidrico. Antes de intentar la instalacion u operacion, el usuario debe familiarizarse con cada uno de los conponentes, particularmente con el generador de desinfectante. GENERADQR DE DESINFECTANTE El generador de desinfectante es una caja de plastico dividida en dos celdillas, el anodo (rojo) y el catcdo (negro). Vista superior de un generador de desinfectante abierto 3 I- El costado anodico produce los gases desinfectantes. Puede reconocerse por una tapa grande y el cable rojo conectado a la misma. a. Tanto la sal como el agua pasan por el agujero cubierto por la tapa grande. b. La ventanilla de observacion muestra los niveles de sal y de agua. c. Las aberturas de rebose permi.ten la salida de cualquier exceso de agua salada. d. Anodos: barras de metal (titanio) , las cuales atraen a los oxidantes de desinfeccion (los cuales se convierten en gases) de la solucion de sal. Vista exterior - con la tapa grande remov' M a' Vista interior U 11- El costado catodico produce gas de hidrogeno y canstico (hidroxido de sodio) , que son los derivados del proceso. Puede reconocerse por la tapa pequena y el cable negro conectado a la misma. a. El agua penetra por el agujero cubierto por la tapa pequena. b. Conector bianco en forma de T para la abertura de hidrogeno y el exceso caustico del catodo. c. • la parte inferior del conector permite que saiga la solucion de agua/hidroxido de sodio • la parte superior del conector permite que escapen los gases de hidrogeno. Catodo: la lamina de metal (acero inoxidable con agujeros) atrae al sodio y al hidrogeno de la solucion de sal. Vista superior sin la cubierta Vista exterior tapa pequena removida 5 III. La membrana* La membrana es una de las partes mas jjnportantes del generador de desinfectante. la misma separa a los compartimientos del anodo y del catcdo. El proceso funciona de la manera siguiente: a. El scdio (de la sal) y el hidrogeno (del agua) pasan por el costado catodico (-). b. El gas de hidrogeno se produce en la celdilla del catodo. Considerando que el misivto es mas liviano que el aire, escapa hacia arriba. Se instala un tubo de escape para expulsarlo hacia afuera. c. El cloro no puede pasar a traves de la membrana y permanece en la celdilla del anodo (+) . Esta mezcla de cloro y oxigeno en forma de gas es dirigida al sistema de abastecimiento de agua, para su desinfeccion. U K&Pk? * La membrana es muy delicada y jamas deberia tocarse a menos que se linpie con un chorro de agua. \ SBGURIDAD Maiitenga esta informacion sobre la seguridad en mente cuando trabaje con la unidad. 1- Instale la unidad de MOGGOD en un lugar bien ventilado. 2. Evite respirar las emanaciones provenientes de la unidad. 3. No ponga sus manos en el liquido que se encuentra en cualquiera de los compartimientos del generador de desinfectante. Si algun objetx> se cayese dentro de un cxsnpartimiento de la unidad, trate de rescatarlo con una varilla o una iranguera de plastico. 4. ATENCION: Evite que el liquido de la unidad entre en contacto con sus ojos o su piel. 5. Evite que el liquido de la unidad entre en contacto con su ropa — _ producira manchas o agujeros. 6. NUNCA permita a sus nifios jugar cerca de la unidad. nirios lejos de la unidad cuando linpie la misma. Mantenga a los Si us ted sufre un aocidente, siga los procedimientos que se especifican mas aba jo. ENTONCES SI Su piel entra en contacto con el liquido del costado del catodo Lave INMEDIATAMENTE el area con agua. Cualquier liquido de la unidad entra en- contacto con sus ojos lave los ojos inmediataroente con mucha agua. i 7 MlKsI AT J-ZS NECESARIOS Los siguientes articulos doben estar disponibles para poder llevar a cabo el manten.tmie.nto. [ ] 1- Hidrometro [ ] 2. Manguera (para lavar y limpiar) conectada a un suministro de agua. [ ] 3. Tubo de 3/8 de pulgada para trasegar con sifon (tres pies de largo, o un metro). [ ] 4. Llaves de tuerca que son parte del equipo. •> 1 :•. • •...•>?.<r. \.~*\ "~^25™SSSJS 4 1 ' "" ^ %ai#- 8 [ ] 5'. [ J 6. [ J 7. Tasa de medir, lxjtolla, o !>a.lde. Balde de plastico para el liquido del catodo. Sal. (Utilice sal pura. Esto reducira al minimo los problemas de operacion y mantemmiento, y vale el aumento del costo. No use sal de mar.) La coiriumdad debera tener disponible una provision de sal para un ano —aproximadamente 15 bolsas de 50 libras cada una. •) I I.j'sTA UK VaUFJCAClON PARA OPKRACIONES Y MANTENIMTFIN'rO Utilice esta lista de verificacion para recordarle las tareas que usted debe llevar a calx) en forma regular. Diariamente: [ J Examine el medidor de amperios todos los dias. Compare la posicion de la aguja con la linea roja indicada en su regulador de potencia. (Esto indica el nivel de amperios nocesario para mantener el nivel de desinfecxante que se desea.) Ajiistelo como sea necesario. (Vea los procedimientos de prueba de ajustes en la pagina del Manual de Instalacion y Puesta en Funcionamiento.) Es posible que usted tenga que ajustar los amperios si se desarrollan cambios en la calidad del agua sin elaborar (tales como una inundacion) . 10 [ ] Examine la ventanilla de observacion y asegiirese de que el nive] de sal alcanza la lino.i indicada. Agregue sal cuando SOT necasirir-[ ] Examine la ventan.il.la de observacion y asegurese de que el nivel de agua en el costado- anodico se mantiene entire las marcas ijndicada.s. Agregue agua cuando sea necesario. Evite sobrellenar. 11 I [ ] Agregue agua al costado catodico, utilizando la tasa de medir proporcionada. Semanalmente: [ ] Bvaiue la dejisidad del liquido del compartimiento del catodo con el hidrometro. (Veanse las instrucciones en la pagina 13.) [ ] Complete las verificaciones residuales de los desinfectantes en ej. sisters hidrico, una vez por semana. (Veanse las instruociones correspondientes al equipo para la evaluacion del cloro.) Mensualroente: [ ] Complete la limpieza mensual. Veanse las instruociones en la pagina 15. ( VERIFICACION FOR MEDIO DEL HIDi^QMErRO Usted llevara a cabo la verificacion por medio del hidrometro una vez por semana, para determinar que el liquido (hidroxido de sodio) en el costado catcdico posee la densidad apropiada (concentracion), para el funcionamiento eficaz de la unidad. El hidrometro es igual al utilizado para verificar la bateria de un automovil. Si usted no dispone de un hidrometro, siga los pasos indicados en la pagina siguiente. Verificacion por medio del hidrometro 1. Remueva la tapa negra del costado catcdico. 2. Introduzca el hidrometro hasta el fondo del compartindento del catodo y apriete la perilla y sueltela hasta que el liquido llene el hidrometro. La. parte flotante dentro del hidrometro esta diferenciada por una zona verde, una blanca y una roja. 3. El nivel del agua deberia permanecer a 1/4 de pulgada por eix^ima o sobre la seocion roja del medidor flotante. 13 .. r ENTONCES SI El nivel del agua esta por debajo de la zona roja, el liquido es demasiado fuerte o debe diluirse Agregar un l i t r o de agua de lluvia o agua destilada y examinar nuevamente. Repita e s t e procediiniento, s i es necesario, hasta que el n i vel del agua este por encima del tope de la zona roja.. El nivel del agua se encuentra a 1/4 de pulgada por encima de la zona roja Exanunelo nuevamente en uno o dos d i a s y agregue agua cuando sea necesario. El nivel del agua se mantiene siempre por encima de la zona roja Disminuya la cantidad de agua de l l u v i a que agrega diariamente a l cortpartimiento del catodo. Si no se dispone de un hidroinetro Si usted no dispone de un hidrometro, ajuste el regulador de potencia para que indique cinco amperios, y agregue agua dentro del costado catodico hasta que e l indicador baje a cuatro amperios, y despues p a r e . (Este procedimiento debera tomar e n t r e t r e s y cinco minutes.) 14 UMPIEZA MENSUAL Usted debe tener mucho cuidado ciiando ] jnipie el MOGGOD. Evite respirar las emanaciones. Evite que su piel o ropa entren en contacto con el liquido de los costados del catodo o del anodo. Repase los procedimientos de seguridad que aparecen en la pagina 7, antes de llevar a cabo la limpieza. PRIMERO, interrurnpa la electricidad: 1. Apague la unidad. a. Haga girar al dial hasta que el indicador muestre debajo del cero. Desconecte la electricidad (desenchufelo) Desconecte los cables rojo y negro de la unidad de potencia lueqo, rieutra 1 ice el gas: 2. Llene el hidroinetro hasta la mi tad con el liquido (hidroxido de sodio) del costado catodico, introduciendolo en el costado catodico a traves de la tapa negra pequefia. 3. 16 Agregue el liquido del punto 2 al costado del anodo, colocando el hidrometro a traves del agujero de la tapa roja. lueqo, desconecte todos los tubas y los canos: 4. Desconecte la linea del gas (tubo flexible de 3/8 de pulgada) 17 Desconecte el tiibo de ventilacion de hidrogeno (CPV de 3/4 de pulgada) de la parte superior del conector bianco en forma de T. 6. Desconecte los tubos de descarga del hidroxido de sodio de la parte inferior del conector bianco en forma de T. 18 Vacie ambos campartiraientos: 7. Abra las abrazaderas y remueva las tuercas de oreja y las arandelas. Reniueva la tapa del generador de desinfectante. Coloque las arandelas y las tuercas de oreja en un lugar seguro. 19 20 8. Ahora es necesario remover todo el liquido del MOGGOD. PR'IMKRO saque con sifon el liquido del costado ancdico (tapa roja) . Atencion: es posible que se emitan gases durante el procedimiento de trasegado con sifon. JAMAS intente sacar con sifon utilizando su boca. Como trasegar con sifon: a. Llene el tubo de sifon con agua. No debera haber burbujas. Coloque sus pulgares sobre cada extreno del tubo, y aguante el agua en su lugar. 21 c. d. Coloque un extremo del tubo dentro del foixlo del costado anodico de la unidad, y mantejxja el otro extremo cerrado con su dedo. Cologne un extremo a un nivcl mas bajo que el MOGGOD para vaciar los contenidos en un balde o botella de plastico. Retire su dedo del extrerno de desague para poder drenar el liquido del cxsipartimiento del anodo. \ e. 9. Una vez conpletado el desague, cleve el extremo del tubo correspondiente al anodo para oscurrir el liquido res tan tc. Enjuague el tubo con agua. Luego remueva con sifon el liquido del conpartimiento del catodo y coloquelo en vn receptaculo de plastico separado. Siga las indicaciones que se especifican en el paso 8, supra. Guarde dos litres de este liquido (hidroxido de sodio) para utilizarlos mas tarde en la puesta en funcionamiento de la unidad. (Puesta en funcionamiento, paso 3b.) \ 23 10. Cuando ambos compartimientos estan vaci.os, recoja la unidad y llevela al lugar de limpieza. Enjuague AMBQS compart imientos con agua para rejrover los sedimentos e impurezas que podrian haberse acumulado en los compart imiontos. 11. lave la membrana con agua. EVTTE TOCAR LA MEMBRANA! No intente limpiarle con un cepillo o cualquier otro objeto. Solamcnte enjuaguela con agua. LA MEMBRANA ES MUY FRAGIL. * Si la calidad de la sal que se utiliza es muy baja, o si se utiliza un chorro de agua fuerte, la mejnbrana eventualmente acurculara calcio y iragnesio. Esta acumulacion aparecera en forma de una capa pesada de color blanco/gris. Entonces, sera necesario: a. empaparla en vinagre introduciendo viriagre en el dostado del anodo del generador b. enjuagarla entonces con agua. No habra necesidad de remover la membrana del generador para su liiipieza. 12. El resto de los liquidos que usted ha vaciado de los cxxnpartimientos del anodo y del catodo pueden descargarse en la alcantarilla. Si no existiese dicha alcantarilla, los mismos podran descargarse en un hoyo pequeno en la superficie. (El hidroxido de sodio proveniente del costado catodico puede utilizarse como un limpiador de plomerias. Ver pagina 42 para otros usos.) 13. Ponga en funcionamiento el M0GGOD siguiendo las instrucciones de la •-' pagina 25. \ 24 PUESTA EN FUNCIONAMIENTO No enchufe el cable a la unidad de potencia hasta que llegue al paso 10. Prepare una solucion de aqua salada saturada en un balde o una botella: empape las piedrillas de sal con agua de lluvia o agua destilada hasta que no puedan disolverse mas. Coloque el agua a un lado. No utilice el agua hasta llegar al paso 4. Prepare el coitpartiitiiento del catodo: a. Llene el oostado del catodo con agua de lluvia (o agua destilada). 25 Agregue todo el hidroxido de sodio (caustico) que usted guardo durante el proceso de lirrpieza del costado catodico. (introduzca fotografia) Prepare el cximpartimiento del anodo: a. Llene el conpartimiento del anodo (tapa roja) con sal, hasta el nivel indicado en la ventanilla de observacion. Agregue aqua salada saturada lentamente hasta el nivel de las tuercas superiores de la ventanilla de obsrevacion. Cuando el agua cxanienza a gotear por las aberturas de rebose en el cx>stado del generador de desinfectante, significa que usted ha agregado suficiente agua. 26 Armg_.DUgyamente la unidad y conecte las tuberias 5. Asegurese de que las juntas que corren por debajo de la tapa no tienen tierra o sal. Coloque la tapa en la unidad. Examine las abrasaderas exteriores para asegurarse de que no haya acumulacion de sal, y limpielas cuando sea necesario. Junta •Abrazadera 6. Conecte nuevamente l a l i n e a de gas (tubo f l e x i b l e de 3/8 d e . p u l g a d a ) . 27 Conecte nuevamente el tubo de ventilacion del hidrogeno a la parte superior del conector bianco en forma de T. Conecte nuevamente el tubo de descarga a la parte inferior del conector bianco en forma de T. Conecte nuevamente los cables rojo y negro a la unidad de potencia. Conecte el regulador de potencia a la fuente de potencia, enchufandolo en una toma de electricidad. (intrcduzca la fotografia del campo) Coloque el dial del regulador de potencia en la marca indicadora roja. t...._. 28 REPARACTON DEL GENERATOR DE DRSIM^CTANTE La unidad generadora de desinfectante MOGGOD es rnuy durable y sin desperfectos, y rara vez necesitara reparaciones. No obstante, es posible que haya instancias en las cuales el mantenimiento por si solo no es suficiente para asegurar la operacion correcta del sistema. Las secciones siguientes le proporcionaran ayuda para llevar a cabo las reparaciones basicas. 29 •REPARACION DE DESPERFECTOS Sintomas Medidas Si el medidor de anperios en el regulador de potencia no indica ningun tipo de corriente Primero, asegurese de que no ha habido un corte de luz a. si hay electricidad, entonces examine el fusible en la parte frontal de la unidad de potencia, y reemplacelo si es necesario. (Ver las instruceiones que aparecen en la pagina 34.) b. si el medidor aiin no registra corriente, asegurese de que la unidad de bombeo esta funcionando y examine el fusible o los interruptores de circuito en el suministro de potencia principal. Si hay un fuerte olor a gas de cloro en la habitacion o recinto protector. Si no hay residuos de cloro en el suministro de agua (despues de haber pasado por el tubo de Venturi). Dirijase a la grafica que aparece en la pagina 32, para procedimiento de reparacion de desperfectos. asegurese de que no ha habido un corte de luz siguiendo los procedimientos indicados mas arriba. t en caso de no haber sufrido un corte de luz, dirijase a la grafica que aparece en la pagina 32, para procedimientos de reparacion de desperfectos. 30 Si'.ntomas Medidas Si usted tiene un'flujo continuo pero o un residuo de cloro, cuando hace el examen del cloro. Cambie la membrana Si el anodo despide un olor dulce (en lugar de un olor fuerte de cloro). Cambie la mcmbrana Si la membrana esta rota o perforada. Cambie la membrana Las abrazaderas exteriores de la tapa del generador de desinfectante no permanecen cerradas. Examinelas por acumulacion de sal y limpielas. '31 GKAFICA PAHA TA KEPAHACIQN DE IX5PTMT3CiX3S Si hubiese olor a cloro alrededor del sistema MOGGOD, podria haber varias explicaciones para alio. Utilice la grafica que se indica mas aba jo para tratar de detcnninar la causa. Rcpare el flujo de agua Llame su emprcsa de agua iene el sistema un flujo de agua? Abra o a j u s t e l a s valvulas Limpio Esta el tubo de Venturi tapado con tierra? > Estan abiertas las valvulas de Venturi? Examine el sistema por si tiene perdidas (vea el dibujo en la pagina siguiente) Esta aspirando el tubo? Enderecelo o destapelo Corrijalo Esta torcido o tapado el tubo de gas? Esta conectado en ambos extremes el tubo de gas? Hay olor a cloro? OOMIENZO 32 Si el Venturi no tiene aspiracion, e>:amine las conexiones siguientcs No lograra aspiracion en el tubo de Venturi si: a. no hay flujo de agua en las tuber ias principales, b. las tuberias'de gas estan desconectadas en el Venturi o en el generador, c. la valvula B esta oonpletaroente abierta, d. las valvulas C o D estan cerradas, e. el tubo de Venturi esta tapado con tierra, f. las tuberias de gas estan tapadas o torcidas, g. la bonfca tiene una obstruccion de aire. 33 OOMO CAMI3IAR EL FUSIBLE EN EL REGULATOR DE POTENCIA Cuando se del^e reemplazar el fusible a. Si el medidor de amperios en el regulador de potencia no indica ni.Jigi.ma corriejite, apague el regulador de potencia. b. Examine el fusible en la parte frontal del regulador. Si el fusible estuviese quemado, reemplacelo. Usted podra reconocer a un fusible quemado observando unos puntos enncgrecidos y el filamento roto. Como reemplazar el fusible 1. De vuelta la perilla negra pequena 1/4.de pulgada (en la parte frontal del regulador de potencia) . 2. Remueva el fusible quemado y tirelo. Introduzca el fusible nuevo en la perilla negra. extremos es indiferente. La posicion de los Empuje la perilla negra completamente dentro del receptaculo y enrosquela, con el fusible adentro, nuevamente al regulador de potencia. 3A Rem leva la membrana. Coloque la membrana nueva. La par-te de la junta blanca debe colocarque contra la pared separadora. Ajuste las tuercas hasta que la punta de los pemos aparezcan en la superficie. Llene la unidad con agua y sal, hidroxido de sodio, etc., siguiendo el procedimiento de puesta en funcionamiento. Coloque la tapa en su lugar. Ajuste las abrazaderas y las tuercas de oreja. Coloque los tubos flexibles de rebose en su lugar. J<> REEMPLAZO DE IAS BNUZhS ANODICAS Y CATODICAS Coando se debe reemplazar la barra anodica Es muy raro que se tenga que reemplazar el anodo. Su tiennpo de duracion esta estimado entre siete y diez anos. Si es necesario reemplazarlo, refierase a los pasos siguientes: 1. Remueva la tapa de la unidad y siga los misroos pasos utilizados para la limpiezaroensual,pasos 1 a 12 (comenzando en la pagina 15). 37 Afloje la(s) tuerca(s) que conecta el anodo a la pared de la unidad. (Ev.ite remover las tuercas complete mente, solo debe aflojarias.) Deslice la barra anodica hacia arriba y hacia afuera del perno. Deslice Pa nueva barra anodica hacia abajo y sobre el perno. Ajuste las tuercas. 38 Cuando S G debe reemplazar la barra catodica Si el catodo se halla muy picado en la proximidad de la superficie del liquido. Reemplazo del catodo; 1. Remueva la tapa de la unidad y siga los misrnos pasos que se utilizaron para la linpieza mensual, pasos 1 a 12. (Coroenzando con la pagina 15.) 39 Afloje la tuerca que conecta el catodo a la pared de la unidad. (Evite sacar la tuerca conpletamente, solo debe aflojarla.) Deslice la plancha catodica hacia arriba y hacia afuera del perno. Deslice la nueva pi catodica hacia abajo y sobre el perno- Ajuste el perno. 40 • El hidroxido de sodio puede descargarse en el suministro de agua. No causara dafio al agua y ajustara el pH. • El hidroxido de sodio puede guardarse y agregarse mas tarde al suministro de agua. • El hidroxido de sodio puede utilizarse para limpiar el sumidero o el inodoro. • El hidroxido de sodio puede aLmacenarse en un recipiente no corrosivo y utilizarse para hacer jabon. 42 SECRETARIA DE SALUD SUBSECRETARIA DE REGULACION SANITARIA Y DESARROLLO DIRECCION GENERAL DE INVESTIGACION Y DESARROLLO TECNOLOGICO CELDA ELECTROLITICA MANUAL DE OPERACION Y MANTENIMIENTO fc.N i I C E D A T 1987. I N D I C E INFORMACION GENERAL ----- ESTRUCTURA DE LA CELDA ELECTROLITICA INSTRUCCIONES DE OPERACION MANTENIMIENTO DE LA CELDA ELECTROLITICA - - RECOMENDACIONES - ACCESORIOS Y REACTIVOS mi - 1NF0RMACI0N GENERAL Debido a la accion de corriente directa. la Celda Electrolitica ioniza soluciones de cloruro de sodio, produciendo cloro gaseoso. Al ser dosificado este al agua para consumo humano, produce la desinfeccion y potabilizacion bacteriologica. PRINCIPIO DEL METODO La Celda Electrolitica se basa en el proceso de electrolisis, esta forir.ada por dos compartimientos;uno de ellos contiene una solucion de cloruro de sodio en agua y, el otro de hidroxido de sodio tanbien en agua. Al pasar la corriente electrica a traves de los electrodos y soluciones, y de acuerdo con la intensidad medida en amperes que proporcione una fuente de corriente electrica regulada, la celda producira cloro mediante una reaccion de electrolisis en el compartimiento del cloruro de sodio. El gas cloro sera introducido a la tuberia del agua mediante un inyector Venturi logrando con esto 'desinfectar el agua de consumo humano de poblaciones rurales hasta de 2000 habitantes. El el compar- timiento de hidroxido de sodio se producira hidrogeno que se desprendera a la atmosfera. ESTRUCTURA DE LA CELDA ELECTROLITICA (Ver Fig. 1) La eel da ( A ) contiene una solucifin saturada de cloruro de sodio y un electrodo de grafito ( 2 ) . La membrana de Nafion (3) es un polfmero permeable a cationes (iones po^ sitivos) y compuestos polares. Es impermeable a aniones (iones negativos) y a compuestos no polares. La celda Qi) contiene una soluci6n de hidr6xido de sodio y un electrodo de acero inoxidable. Los.electrodos estan conectados a una fuente reguladora de corriente dj[ •recta; el electrodo de grafito esta conectado al polo positivo (5) de la fuente y el de acero inoxidable esta conectado al polo negativo (6) de la misma. El cuerpo de la celda ( A ) contiene un orificio de desahogo ( 7 ) el cual permite que la presifin atmosferica ayude a la extracciSn del cloro gaseoso que sera extrafdo por un inyector Venturi. La tapa (8) de la celda tiene en cada uno de sus extremos dos orificios: r 1. En la celda (A) - Orificio alimentador para cloruro de sodio (9) - Orificio para la salida de cloro gaseoso (lo) i. En la celdafB - Orificio alimentador\para hidrfixido de sodio (1 - Orificio para la salida de hidrfigeno gaseoso 02, INSTRUCCIONES DE OPERACION Disolver 900 gramos de cloruro de sodio en 3 litros de agua destiiada y depositaries en la celda Q y . Disolver 300 grarnos de hidroxido de sodio en 3 litros de agua destiiada y depositaries en la celda ( B ) . Colocar la tapa (s) fito (^ ble (Q de la celda, de manera tal que el electrodo de gra- quede sumerfido en el cloruro de sodio y el de acero inoxidaen el hidrdxido de sodio. Conectar el electrodo de grafito (2) al polo positivo (5) de la fuente reguladora. Conectar el electrodo de acero inoxidable Q y al polo negativo ^ ) de la fuente reguladora. Conectar la manguera de succion del cloro a la celda (Jty y al eyector Venturi. Tapar los orificios de alimentacidn (9) y Q p de ^ as celdas con sus res^ pectivos tapones. Dejar libre el orificio (12) de salida de hidrdgeno. Pennitir el paso del agua a traves del eyector Venturi Conectar la fuente" reguladora.\ La produccidn de cloro es proporcional a la intensidad de corriente o amperes que sean pasados a traves de la celda; es decir a mayor amperaje, mayor produccidn de cloro y viceversa. - Imciada la operacion de la celda, esperar 10 minutos para detenmnar cloro. - Comenzar con la toma mSs cercana a la instalaci6n e ir avanzando a tomas domiciliarias mSs alejadas para determinar los amperes en la cual la celda debe trabajar, procurando no exceder los 7 amperes de alimentacifin. MANTENIMIENTO DE LA CELDA ELECTROLITICA Proporcionar mantenimiento cada 100 horas de tuncionamiento de la celda. Esto depende de la calidad de la sal utilizada, ya que algunas marcas del mercado presentan mSs impurezas que otras. Apagar y desconectar la fuente reguladora de voltaje. Desmontar las conexiones electricas de ambos electrodos (|) y (4). Desconectar todas las mangueras 0 conexiones que esten sobre la tapa Qi) de la celda. Desmontar la tapa de la celda. Dcsechar las soluciones de las celdas ( A ) y (F) por medio de los tapones de desague O . Enjuagar con chorro de agua ambas celdas ^ ^ Desmontar el portamembrana ( p y y (jy y desaguar nuevamente. a chorro de agua, lavese. Secar las celdas ( A ) > T B ) y el portamembrana (T) Volvier a montar el portamembrana ("M respetando la colocacion inicial, ya que !la membrana Nafion ^3) tiene funciones diferentes en cada uno de sus ladob. T Seller con silicon las uniones del portamembrana (T) a su soporte para no ',-"^rmHtir fugas por las uniones. •* Asegtirar que el material rojo de empaque este ubicado en su lugar, \en •' defepto sellarlo con silicon. Si es necesario, reemplazar 0 reparar las conexiones y cables electricos que tonectan los electrodos. su RECOMENDACIONES El cloro es un gas (mortal) m5s pesado que el aire; por lo que si se pre senta una fuga debe desconectar inmediatamente la fuente reguladora de voltaje, permi'tir una ventilacifin abundante y abandonar el Srea. El cloruro de sodio se adiciona de acuerdo al control que se tenga de clc) ro residual en las tomas dimiciliarias, pero es conveniente cambiarlo cada 8 dias. El hidroxido de sodio es una solucifin que produce quemaduras graves en la piel u ojos por lo que se debe lavar inmediatamente con abundante agua la zona afectada. En la piel aplicar una soluciSn al 50% de acido acetico y en y en los ojos una solucion de 30 grs de bicarbonato en un litro de agua potable. Cada 10 dias se diluye el hidroxido de sodio con 50 ml. de agua ya que este - aumenta su concentraciSn. En ciertas proporciones, el hidr<5geno puede ser explosivo, por tal motivo no debe ser retenido; ni fumar en el Srea de ubicacicm de la celda. : \ zJ'Jfoo Itocar ninguna de las soluciones con los dedos cuando este funcionando\ ! la ;celda, ya que existe riesgo de electrocutarse. Al desechar las soluciones, tenga precaucion de no salpicarse ya que exis • te el riesgo de quemaduras. - El orificio contenido en el cuerpo de la celda no debe estar obstruido. - Al estar la celda fuera de operacifin, se debe retirar uno de los cables de los electrodos de la fuente reguladora de voltaje. - Es recomendable usar sal no yodatada (de grano). - Al lavar el portamembrana no utilice cepillos ni otros objetos ya que se puede romper la membrana. \ 2 l ACCESORIOS Y REACTIVOS 1. Fuente reguladora de re:•hi^-^n c c vvi tf *. *£ 1. Manguera de 1/4 3. Solucifin de c l o r u r o de sodio, to psae&as&wsssa eb &xzte c^.v^^^^s 4. SoluciSn de hidrfixido de sodio. de pulgada para l a succifin del gas c l o r o . p«fcs. > X > - i. ; iI ,* mmmmm ^j -o ^i Ul en ui Ui ut Ul Ui IPER ~j > £T Ul *""" "* PI 3: 0 O H >Q i-t> 0 H- 1 M 1 •I ft r- H 1 W o 3. 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U~ » ~ V ~ . < r r M v i^ n ^ _> Jw 1 -n i v^" vO U,' to .v ,> ! i 1 - - dCir^afo t « » - ^ K p \>\ \?\ V - i 1 i^. o V ai ui H o <3 • > i I o Ok i ! O Tl 3 «a 1 o a 3 r >5 % ~" Z a ^ —* IO ^j «.a^^ ^» * ~ u r- b 4 £ lr> V.V S* v« v^ -* C^ ^ r^> X Ul 0T\ j \ o X> v' v^ +•* 8o •» J? 33 H O H O r o •^ s 5» x o SOME TRICO FIGURA 5 r 1 c^n^> CORTE TRAR-SVERSAL FIG. 6 r CELDA ELECTROLITICA 9* rv t4 * | * 3 <0 a a H « * N - O «0 • a • -J • w £ - W i 2 •7 • T R c m 0) 1 H 1 1 .• 1 c 6 0 L1 0 m * r> 1-" I ra: c r < rr> mc m2 r CO 31 H > 0 i — I CD x | 1 5 a* m — 2 ae t > H 0 m 0 to CO 1 • m ^ r 0 5 —— r- O 0 0 tn o > o oc o _ nC o > \z > f? r> G. e: CO 0 a: > 0 c > r3 \ \ - ! 1 "~ 1 1 • ^^ — M M *J i '. —• ...... —— i.. _ « . - ^- 1 : ^,-^.r .,-..,, -0 j | 1 1 ! j > ... • 2 rn £ 3D 1 S > 3 * r*i ! | ! eg ; 1 0 ! 1 J—«-. ..,~,. * . , - . • - -. H • , •*• -.»» .«_•_.-.• - . . * -~—J J* V J D P E R A C I O N D E E Q U I P O S V M/\I\JT LEfXJIMIEfMTQ O Z O N O C L d R A O O R E S o p e r a d o r e s d e p l a n t a Oper-OXI-GIDOX-1 O P E R A C I O N R e c o r d a r EL EQUrPO SOLO DEBE ESTAR FUNCIONANDO SI KL AGUA A TRATAR ESTA CIRCULANDO I -c=^=y\ ' / J rAsx C/3 O o n t r o l e s c l .i. a r i o s 1 . CEL.DA Q U E T^A. : T'ENOA _ri A G U A V /?6<y-9 NS*< « .-3 x. °/««I Si no t u v i e r a . se deberan agregar! - \ f' • S/XL, » Oper-OXI-GIDOX-2 2 . L/\ O K N 3 XD A D D E L/\ S O I ^ U O T O N OK Para ello use el densimetro. Saque la tapa e introduzoa el densimetro hasta el fondo en el compartimento de la solucion de soda. Apriete la pera de goma y de.je que el liquido eritre en el tubo El nivel del liquido debe estar dentro de la zona verde en los equipos GIDOX 6 dentro de los valores 10r>0 - 1125 en los equipos OXT. m Cuando la solucion este muy densa ocurrira que el nivel estara n 1.125 I A EQUIPOS GIDOX EQUIPOS OXI Cuando esto ocurra, habra que diluir la solucion de soda. Para ello: \ AGREGUE AGUA HASTA QUE LA DENS 1 DAD ESTE DENTRO DE LOS VALORES ACON'SE^JADOS (Vol. de agua a agrogar = i/3 - 1/2 del volumen de la camara de soda) Mant-OXI-1 M A N T E N I M I E ^ N T Q F r e c u e n c i C OX IE > a De acuerdo al tipo de sal usada sera de mantenimiento: la frecuencia SAL PURIFICADA STERLING = CADA 5 MISSES DE OPRRACION CONTINUA SAL COMERCIAL COMUN = cada 1 MES DE OPERACI.ON CONTINUA La f o r m a ole^ r e a l x z a r l a 3CD 1. CORTE LA CORRIENTE 2. DESCONECTE LOS CABLES ELECTRICOS AFLOJANDO LAS TUERCAS EN LA PARTE POSTERIOR DEL COMANDO Y RETIREL09. Mant-OXI-2 • 0_Q 3. DESCONECTE EL TUBO DE LOS GASES EN LA TAPA DE LA CELDA. 4. INCLINE LA CELDA DE FORMA QUE LAS SOLUCIONES EN AMBOS COMPART!MEN TOS SALGAN POR LOS DESBORDES. COLOQUE UN RECIPIENTS EN LA DESCAR GA DE LA SODA P'JES ESTA SOLUCION VOLVERA A SER UTILIZADA. LA OT'RA SOLUCION SE DESCARTARA. / n 5. QUITE LAS TUERCAS DE LA TAPA Y RETIRE LA MISNA. Mant-0?U-3 6. ENJUAGUE EL INTERIOR CON AGUA. REMUEVA LOS ELECTRODOS QUITANDO LAS TUERCAS QUE LO SUJETAN, PARA QUE LA MEMBRANA QUEDE ACCESIBLE. PUEDE QUITAR TAMBEEN EL DIVISOR PARA LA SAL. 3- ENJUAGUE LA MEMBRANA DE AMBOS LADOS DEJANDO CAER CHORftOS DE AGUA SOBRE LA MISMA. PERO NO TOQUE NI RASPE LA MEMBRANA. SI LO HACE, LA MEMBRANA SE MALOGRA V TODO EL EQUIPO QUEDARA INUTILIZADO Mant-OXI-4 9. REINSTALE EL DIVISOR PARA LA SAL Y LOS ELECTRODOS. ATENCION: EL ELECTROUO DOBLE DEBE IR EN EL COMPARTIMENTO DE LA SAL. 10. COLOQUE LA TAPA Y ASEGURELA POR MEDIO DE LAS TUERCAS. A ti Q Q 1. ECHE LA SOLUCION DE SODA QUE HABIA GUARDADO EN EL COMPARTIP1ENTO CORRESPONDIENTE. APROVECHE PARA MEDIR LA DENSIDAD. SI ESTUVIERA MUY DENSA: DILUYALA. Mant-OXI-b /?££/* Srtt O o 12. LLENE CON SAL EL COMPARTIMENTO DE SAL Y LUEGO LLENE ESE COMPARTI MENTO CON AGUA. /VgCs&o Rojo ^?oro tJcc#o 1.3. CONECTE EL TUBO DE LOS GASES Y LAS CONEXIONES ELECTRICAS (CABLE ROJO AL TERMINAL ROJO Y CABLE NEGRO AL TERMINAL NEGRO). OH ~ts>- I 14. CONECTE LA CORRIENTE Y REINICIK LA OPERACION. ASEGURESE DE QUE POR LA TUBERIA CIRCULA EL AGUA A TRATAR. Mant-GIDOX-i M A N T E N I M I EIMTO C C3 X O O X ) F* i r e c u e n c i at De acuerdo al tipo de sal usada sera la frecuencia de mantenimiento: SAL PURIFICADA STERLING = CADA .5 MESES DE OPERACION CONTINUA SAL COFJERCIAL COMUN - CADA 1 MES DE OPERACION CONTINUA Lji.3 f o r m a d e jr-<oa.l •'. '^c £3. JT' 1 £3. . . . o OFf r 1. APAGUE EL EQUIPO LLEVANDO A LA POSICION OFF LA LLAVE EN EL MODULO DE COWANDO. Of" 2. DESCONECTE LOS CALBES ELECTRICOS AFLOJANDO LAS TUERCAS EN LA PAR TE POSTERIOR DEL COMANDO Y RETIRELOS. Mant-GIDOX-2 n (In Q TJ J 3. DESCONECTE EL TUBO DE LOS GASES EN LA TAPA DE LA CELDA. 4. DESAGOTE LA SOLUCION DE SODA POR MEDIO DE LA VALVULA EN LA PARTE POSTERIOR DE LA CELDA. COLOQUE UN RKCIPIENTE EN LA DESCARGA, PUES ESTA SOLUCION VOLVERA A SER UTILIZADA. 5. DESAGOTE LA SOLUCION SALINA POR MEDIO DE LA OTRA VALVULA. DESCARTE ESTA SOLUCION. Mant-GIDOX-3 6. ENJUAGUE EL INTERIOR DE LA TAPA Y EL INTERIOR DE LA CAJA. PUEDE QUITAR EL DIVISOR PARA LA SAL PARA FACILITAR LA OPERACION. 7. ENJUAGUE LA MEMBRANA DE AMBOS LADOS DEJANDO CAER CHORROS DE AGUA SOBRE LA MISMA. PERO NO TOQUE NI RASPE LA MEMBRANA. SI LA MEMBRANA SE MALOGRA TODO EL EQUIPO QUEDARA INUTILIZADO. ' Q n a 0 3. REINSTALE EL DIVISOR PARA LA SAL Y COLOQUE LA TAPA. Mant-GIDOX-4 A -a 9. ECHE LA SOLUCION DE SODA QUE HABIA GUARDADO EN EL COMPARTIMENTO CORRESPOND!ENTE. APROVECHE PARA MEDIR LA DENSIDAD. SI ESTUVIERA MUY DENSA: DILUYALA. 'Q' n 10. LLENE CON SAL EL COMPARTIMENTO DE SAL Y LUEGO LLENE ESE COMPART.I MENTO CON AGUA. rJZULcn U 11. CONECTE EL TUBO DE LOS GASES Y LAS CONEXIONES ELECTRICAS. Mant-GIDOX-5 ON £ REINICIE- LA OPERACION E.MCENDIENDO EL EQUIPO POR MEDIO DE LA LLAVE EN EL MODULO DE COMANDO (A LA POSICION ON). ASEGURESE DE QUE POR LA TUBERIA CIRCULA EL AGUA A TRATAR. * : # * # * I r" i: i i » r" ~ i ' i. J I o y. J ) m. ] <» \ '"•] ej -3 c ro sz ro 5 uj a 0) > o £ £ -t; c £ ' E .2> ro eu o -^ — • sz «-- o X I "ro c t ; <J SZ 3 C 3 n ™ a) 3 *^ OJ y > ro <u m ro 5 v) •* •— 0) k. 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En mayor o menor medida, los Paises en vias de desarrollo se enfrentan a probleraas que les impiden implementar en forma adecuada programas de esta naturaleza. En algunos casos, es la falta de personal tecnico entrenado adecuadamente; en otros, los costos de equipos e insumos hacen prohibitiva la implementacion de estos programas de vigilancia. Del Agua es una organizacion sin fines de lucro basada en Inglaterra cuyos tres objetivos principales son: apoyar Programas de Vigilancia de Calidad de Agua con cursos cortos de entrenamiento en temas relacionados a vigilancia y tecnicas analiticas de monitoreo; suministro de equipos de monitoreo al precio de costo de manufactura; y respaldo de insumos para los Programas, suministrandolos a precios de descuento obtenidos en el Reino Unido. Las especificaciones del equipo asi como las caracterxsticas de los cursos de entrenamiento y del apoyo que se ofrece se detallan en las paginas siguientes. Informacion adicional se puede solicitar a la direccion postal arriba senalada o a: Mauricio Pardon c/o CEPIS Casilla Postal 4337 Lima 100, Peru Telex: 21052 PE CEPIS Telefono: 35-4135 DelAgua is a non-prof itmakingorganistation concerned with training consultancy in water treatment, water quality surveillance and sanitation in developing countries. Registered Number 1860842 Registered Offices 1 28 High Street Guildford UK a water quality for developing countries Directors B J Lloyd PhD M Pardon BSc D Wheeler SSc Address PO Box 92 Guildford GU2 5TQ England PORTABLE WATER TESTING KIT <s~. / •<: S ,:-1 Components: 1: 2: 4: Faecal colt form bacteriology Membrane filtration equipment and 44°C integral incubator and 12 volt Battery + separate charger Combination chlorine residual and pH comparator. Turbidimeter tubes: High range 20-2000 T,U. Low range <10 Combination electronic temperature and conductivity meter Low range 0 - 200 pS Medium range 200 - 2,000 yS High range 2,000 - 20,000 pS DelAgua is a non-profitmaking organistation concerned with training consultancy in water treatment, water quality surveillance and sanitation in developing countries. Registered Number 1860842 Registered Offices 128 High Street Guildford UK DelA<ft£3 water quality for developing countries Directors B J Lloyd PhD M Pardon BSc D Wheeler BSc Address PO Box 92 Guildford GU2 5TQ England DELAGUA PUBLIC HEALTH TRAINING PROGRAM iKS Specification of a n a l y t i c a l e q u i p m e n t f o r w a t e r t e s t i n g Faecal coliform t e s t Incubator Chlorine - Performed technique filtration schemes by the membrane filtration using integral, purpose made apparatus. section Kits incori :ate incubators which permit the incubation of up to 17 membranes within reusable aluminium petri dishes. residual Performed by a simple comparator method using DPD reagents - results in mg/1. Turbidity Performed by a tube/extinction method for the range 5 - 5000 TU. Filterability For use in conjunction with turbidity for process selection - based on a membrane filtration technique. Conductivity Performed using a robust electronic meter and probe. , Temperature Performed using a robust electronic meter and probe. PH Performed by a simple comparator method using phenol red reagent. \ \The water testing kit is supplied with an integral rechargeable battery, and is capable of independent field operation for a minimum of five days before recharging is necessary. Charging is performed fro^m mains electricity (110 or 220 volts AC) using a matched charger unit which is supplied. The check list of equipment noraally contained within the DELAGUA water testing kit is shown overleaf. DclAgua is a non-profitmsking organic tstion concerned with training consultancy in water treatment, water quality surveillance and sanitation in developing countries. Registered Number 1860842 Registered Offices 1 ?. 8 High Street Guildford UK Directors DelAguS Address water quality for developing countries B J Lloyd PhD M Pardon BSc D Wheeler BSc PO Box 92 Guildford GU2 5TQ England CHECK LIST OF EQUIPMENT Quantity -i rem ll Carrying case with incubator 2: Membrane Filters Consumables 3i Pads and Dispenser Consumables 4t Forceps 5i Aluminium Petri Dishes 6t Gas Lighter 7« Sample Jug and Cable 81 Filtration Tube 9; Tube Support at Upper '0' ring b» Lower '0' ring c» Membrane support 101 Methanol Dispenser Hi Suction Pump 12i Suction cup 13i Turbidity tube 14« Culture Medium (in small autoclavable bottles) 151 Chlorine ) ) ) 16« pH 17« DPD pastilles No. 1 Consumables 181 DPD pastilles No. 4 Consumables 19i pH pastilles Phenol Red Consumables 20i meter 21. Conductivity) ) Temperature ) 22. Conductivity electrode 23i Temperature Probe 24* Tissue/Clean Cloth comparator Consumables DelAgua is a non-profitmaking organistation concerned with training consultancy in water treatment, water quality surveillance and sanitation in developing countries. Registered Number 1860842 Registered Offices 1 28 High Street Guildford UK DelAgua water quality for. developing countries CHECKLIST FOR THE OPERATION OF THE Directors B J Lloyd PhD M Pardon BSc D Wheeler BSc Address PO Box 92 Guildford GU2 5TQ England 'DELAGUA' WATER TESTING KIT YES IS WATER CHLORINATED "> TAKE SAMPLE WITH VACUUM FLASK PERFORM CHLORINE RESIDUAL, pH AND TURBIDITY TESTS NO J$L TAKE SAMPLE WITH STERILE SAMPLING CUP ^ I S FREE CHLORINE RESIDUAL MORE THAN 0 . 1 rag/1 AND TURBIDITY LESS THAN 5 TU NO YES _& PERFORM FAECAL COLIFORM TEST <T" I IS CONFIRMATION OF BACTERIOLOGICAL QUALITY REQUIRED YES. JL ±. NO PLACE MEMBRANE PLATES IN THE INCUBATOR ^ COMPLETE PHYSICOCHEMICAL ANALYSIS ^L TAKE IMMEDIATE <r ACTION INFORM RELEVANT AUTHORITIES WATER QUALITY ACCEPTABLE <r WATER QUALITY <r FAILURE WATER QUALITY UNACCEPTABLE TAKE IMMEDIATE ACTION INFORM RELEVANT <r AUTHORITIES ML J05S_. YES IS SANITARY INSPECTION SATISFACTORY AND ARE PHYSICOCHEMICAL TEST RESULTS NORMAL AND ACCEPTABLE* YES THE FOLLOWING DAY » IS FAECAL COLIFORM COUNT LESS THAN 1 PER lOO ml NO,&_ IS FAECAL COLIFORM COUNT LESS THAN 10 PER lOO ml NO. YES IS FAECAL COLIFORM COUNT MORE THAN 10 PER lOO ml * ACCEPTABILITY I S JUDGED BY NORMAL WHO C R I T E R I A DelAgua is a non-profitmaking organistation concerned with training consultancy in water treatment, water quality surveillance and sanitation in developing countries. P\ _ I A ~m . . - * DelAgua ..^ , Directors B J Lloyd f Address PO Box 92 --- water quality for developing countries Guildford QU2 5TQ England DEL AGUA PUBLIC HEALTH TRAINING PROGRAMMES DelAgua is a non-profitmaking organisation. The following represent only those charges necessary to cover costs. Training programmes conducted in-country include provision of up to two weeks tuition in public health science, sanitary inspection, water treatment technology, water quality testing, monitoring and surveillance. Any aspect can be emphasised according to the requirements of the commissioning agency. CHARGES Travel and subsistence of two instructors (Latin America) * Equipment (per unit) 1000 USD Air freighting and insurance for equipment (per unit) Course fee for materials (per student) 250 USD 62.5 USD * based on travel fares plus U.N. subsistence allowance rates DelAgua is a non-profitmaking organistation concerned with training consultancy in water treatment, water quality surveillance and sanitation in developing countries. DelAgui water quality for developing countries Directors 8 J Lloyd PhD M Pardon BSc D Wheeler BSc Address PO Box 92 Guildford GU2 5TQ England DEL AGUA PUBLIC HEALTH TRAINING PROGRAMMES The following topics and exercises will be incorporated into the two week training programme! Introduction! water-borne and water associated disease! The faecal-oral route of infection* Infective dosest Faecal indicators and pathogens in water> The International Water Decade - goals, legislation and standards» GEMS. Water treatment! the multiple barrier principle! Treatment process selection for rural and sub-provincial water treatment worksj Treatment process design, operation and maintenance! prefiltration, slow sand filtration and disinfection! Commissioning and monitoring (quality control)» Laboratory exercise on disinfection. Sanitary inspection! Field visit for sanitarian duties and reporting results! Infrastructural requirements for action on maintenance and repairs. Water quality monitoring and surveillance! Definition of roles of supply agency and health authorities! Water quality testing! World Health Organisation Guidelines! Volumes I-III. Water testing* Bacteriology! Field preparation of media! Sterilisation of media! Packaging, checking, and maintenance of testing equipment. Water testing! Physico-chemical parameters! Field exercises involving sampling of raw, treated, and distributed water samples! Reporting results. Relevance of standards! Interpretation of water quality results! Formulation of sampling programmes! Water quality and health. DelAgua is a non-prof itmaking organistation concerned with training consultancy in water treatment, water quality surveillance and sanitation in develi ping countries. Registered Number 1860842 Registered Offices 128 High Street Guildford UK DelAgua water quality for developing countries Directors B J Lloyd PhD M Pardon BSc D Wheeler BSc Address PO Box 92 Guildford GU2 5TQ England DELAGUA WATER SURVEILLANCE AND MONITORING SUPPORT SERVICES It is recognised that the cost of consumables for water testing in developing countries is often prohibitive. For this reason DelAgua is resolved to supply all necessary media, membrane filters, pads and spares at cost to any nominated port in the country of use of the water testing equipment. Consumables can be transported by ocean freight or air freight. Prices will be negotiated on bulk purchase in the UK and discounts passed on to the user. Typical current costs for faecal coliform analysis in Latin America by such transfers are less than 0.2 USD per sample. Unfortunately, DelAgua is not in a position to arrange clearance from ports and customs, and does not have the resources to engage agents. Thus clearance must be arranged by purchasers. However, all goods will be insured against damage or loss in transit. It is a condition of transaction that all ' equipment and support services including training be paid for in advance. DelAgua has no administrative support for invoicing in arrears. Whilst every effort has been made to not in a position to guarantee these but DelAgua does guarantee that all supplied at cost and that costs will minimum. quote accurate costs DelAgua is costs for an indefinite period, equipment and services will be continue to be kept at absolute DelAgua is a non-profitmaking organistation concerned with training consultancy in water treatment, water quality surveillance and sanitation in developing countries. Registered Number 1860842 Registered Offices 1 28 High Street Guildford UK f GRUPO "A" RECOMENDACIONES DE INVESTIGACIONES PARA EL FUTURO El grupo reconoce que el equipo de generacion de gases oxidantes MOGGOD, es una herramienta mas para la desinfeccion del agua y que se puede elegir de acuerdo con las condlciones locales sin que esto nec.esariamente constituya la eliralnacl6n de otras alternativas ya en utilizacion. Por tanto, se plantean las sigulentes recomendaciones: •. . La investigacion en relacion a esp^cies de oxidantes, eantidades en que se producen, eficacia de su action, formacion de organo dorados y otros subproductos, que sea /eali^ada por las instituciones cuya infraestructura es perinitida,/debiendo comunicar a los palses y/o instituciones interesadas los resultados de esas investigaciones. Interesar a ACU... . y EPA en trabajos de investigacion en areas relacionadas con el MOGGOD y tratar de involucrar a los gobiernos de los difercntes palses para financiamiento de las investigaciones. La investigacion de la operacion (adaptabilidad, instalacion, operacion, insumos, eostos, seguimiento) sera ejecutada por los palses participantes, debiendo establecerse un protocolo para la investigacion y que los resultados scan compartidos estableciendose un banco de datos al que los paises participantes tengan acceso. 4. El protocolo de investigacion debera contemplar, entre otros aspectos, los sigulentes: 4.1 Analisis de la situacion salud antes, durante y despues del proceso de desinfeccion con el MOGGOD, ^ 4.2 actitud de las comunidades ante las nuevas experiencias, 4.3 acciones de motivacion y educacion sanitaria continuada, las cuales deberan aplicarse en las comunidades a beneficiar. U.d 5.- Desarrollo de tareas de investigacion en materiales a eiftplear en electrodos, membranas y su disposicion, y de las partes constitutivas a fin de atimentar su confiabilidad y eficiencia en la operacion, asi como el estudio de fuentes alternas de energfa. Se utilizara la retroinformacion de los protocolos de investigacion. La OPS debera interesar a los gobiernos, a traves de los conductos correspondientes, para que se lleven a cabo las acciones recomendadas. - 2 - Fomentar la inveastigacion local para la produccion y/o readecuacion del equlpo y sus componentes a fin de mantener en operacion las unidades. DF.SARROLLO Y EVALUACION DE PROYECTOS El desarrollo de la investigacion en su etapa inicial debera realizarse en diferentes condiciones ambientales y/o geograficas e ir acompanada de una informacion epidemiologica consistente antes y despues de la accion de desinfeccion con el MOGGOD. Esta informacion epidemiologica servira como base de sustentacion para la implementacion de futuros proyectos en areas de sirailares caracterfsticas las que solo necesitaran analisis microbiologicos y examenes fisicoquimicos. Replantear y/o continuar el desarrollo de la experiencia con el MOGGOD a fin de establecer o coraplementar la informacion tecnica en forma acumulativa. En otro orden de ideas, ampliar la experiencia con la utilizacion de diferentes equipos. A *. V,,^^ / 4b En todos los casos, establecer comparaciones tecnicas y economoraicas entre MOGGOD y desinfeccion con tecnicas tradicionales. Las investigaciones deberan desarrollarse en un tiempo prudencial, dependiendo de las facilidades y condiciones locales. COLA.BORACION HORIZONTAL E INTERNACIONAL Toda la informacion que se necesite debera ser canalizada a traves de las Representaciones de la OPS/OMS en los diferentes paises. Aprovechar el recurso calificado que exista en las regiones como efecto multiplicador para la difusion de esta tecnologfa. S •* GRUPO "B" RECOMENDACIONES Y FUTURAS INVESTIGACIONES / 1. Objetivo del Seminario a. Presentaclon del equlpo y avarices realizados en cada pais b. Intercatnblo de experiencias v. Desarrollo tecnologico Comentario. En el presence seminario se pudieron apreciar los problcmas de instalacion de los equipos en cuanto a operacion y pnrametros basicos de control (oxidabilidad, analisis bacteriologico, demands de cloro). / ' j 2. Recomendaclones 2.1 Especlficas y 2.1.1 Instalado el equipo, consideramos determlnaciones basicas sobre; ~ demanda de cloro - cloro residual - analisis bacteriologicos: conveniente llevar a cabo las coliformes totales y coliformes fecales Previa a estas determlnaciones, se requiere llevar a cabo un estudio epideiniologico antes de la instalacion de estos equipos de mezcla de gases oxidantes, estudios tales como incidencia de enfermedades gastrointestinales, desnutricion, etc. / (P J 2.1.2 Evaluar comparatlvamente con el equipo de gases oxidantes los otros equipos de desinfeccion que vienen funcionando. 2.2 Generales fit. Gi^KS 1 2.2.1 Que a traves del CEPIS t^rrxrr' una red de informacion sobre el y rfnaaciamionto del equipo de mezcla de gases oxidantes en los paises participantes en el seminario. / 2.2.2 Continuar con la investigacion del equipo y oonitoreo. .. 2.2.3 Recomendar a la industria para la investigacion nacional sobre el perfeccionamiento del equipo de acuerdo a las necesidades y las condiciones propias de cada lugar (unidades de bacteria, sal comun). \ 2.2.4 Vincular a las universldades con el desarrollo de investigacioanes basicas, tendlentes a evaluar y desarrollar la apllcacl6n de la tecnologla. / 2.2.5 Estimular la creacion de pequefias industrias o de capitales locales para la produccion de estos equlpos. ' 2.2.6 ' Incluir en la evaluacion un mayor numero de cquipos para utilizarlos en diferentes comunidades. / 2.2.7 J «/2.2.8 Estudio epidemiol5gico para ver el impacto del sistema de desinfeccion en la comunldad, especialmente en la poblacion infantll. Recomendar el incentivo de la promocion y educacion sanitaria, con la finalidad de propiclar la aceptacion del equlpo de mezcla de gases * ,i . i j j _ j _ _ i _ i .. _ i oxldantes en las comunidades o_ lugares a instalarse. 2.2.9 Se propone tener los\resultados de la evaluacion y desarrollo de 1J investigacion en el periodo de un ano. • Fuentes de financiamlento Para la evaluaci5n y adqulsicion de equipos de gases oxidantes es necesario contar con la colaboracion de las sigulentes entidades: > OPS/OMS UNDP BID AID GTZ C}?EPIS ( a s i s t e n c i a t e c n i c a e i n t e r v e n c i o n mas a c t i v a ) - CIf$ (Holanda) M w U ^ ^ l ^ J c^L Axf<^™^- Colaboracion entre las entidades de salud, universldades En el caso especlfico de cada pais, ver la posibilidad de financiar la preparacion de tesis sobre la evaluacion del equipo de gases oxldantes por parte de los estudiantes. \ GRUPO "C" RECOMENDACION DE FUTUROS PROYECTOS INMEDIATOS /l. Uniformizacion de formatos de captura de datos: a. b. Control de operacion Control de calidad: bacteriologica y fisicoqufmica ' 2. Elaboracion de manuales de operacion y mantenimiento practicos accesibles (a nivel de las personas que manejaran el equipo). y (J 3. Despues de determinar la zona en donde se aplicara el equipo, desarrollar un estudio de morbilidad de la poblacion (por estatus de edades) para observar el impacto social-sanltario de utilizar un nuevo desinfeetante. f 4. Hacer un estudio para determinar el nivel de cloro residual necesario en tanque y/o red de distribucion para obtener agua sanitariamente segura. l/5. Efeactuar un analisis comparativo (tecnico-economico) de la utilizacion del equipo generador de gases oxidantes versus otros procesos de desinfeccion. 6. Desarrollar una tecnologfa praetiea y a bajo costo para la purificacion de la sal comercial. 7. Verificar la produccion de gases oxidantes a diferentes condiciones de presion y temperatura. RECOMENDACIONES A LARGO PLAZO 1. Investigacion sobre la produccion de electrolisis a partir de otro tipo de energla no convencional. 2. Investigaci5n sobre el uso de diferentes electrodos (y su eficiencia) y membranas, con miras a reducir costos. 3. Estudio de la factibilidad de produccion parcial o total del equipo MOGGOD a nivel nacional. 4. Continuacion de la invaestigacion concerniente a la caracterizacion de los gases generados con la finalidad de evaluar sus efectos sobre la salud. —•""'" ' " " ~ ~ " ' o u 4-> o • (/) .no a) x) -H i—i W T-( U) •^ «J X a> 60 CJ O V- E <V X) i—i 1-1 T-i —^. N X 1 1» 60 rH -H <U E O H tJ 1 w xcO O I-l U (0 -H CLI (0 r—* <n 3 E \ u p., o •H fe O > 3 l-H • r-i 4J g o --^ H £ 8r l • 5Z CJ i-l o 0) - ^ Pu pC E O 2 o • S5 r H o s O E o . XI X) w to (0 4) . 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DESCRIPCION DEL SISTEMA ELECTROLITICO Los Alamos Technical Associates, Inc. (LATA) ha desarrollado un raetodo electrolitico simple de bajo voltaje para la esterilizacion del agua potable, que se puede emplear en localidades remotas, pafses en vfas de desarrollo y areas de desastres naturales. El metodo solo requiere de una solucion de sal o agua de mar para producir una mezcla sinergetica de oxidantes directaraente en soluci6n. Un volumen de la corriente del anodo mezclado con 500 a 1,000 voluraenes de agua contaminada extermina rapidamente los microorganismos y patogenos humanos resistentes, produciendo agua apta para el consumo humano y quedando un residual de cloro para irapedir el crecimiento interior de los microorganismos durante el almacenaje y distribucion. Los requerimientos energeticos son 12 V CC, 14A para una unidad capaz de producir 8,000 galones de agua tratada por hora. La unidad prototipo de purificacion electrolitica de agua es un modulo sencillo y resistente. Una unidad modular consta de una bomba, tuberfa, transformador CC, una celda electrolitica de 3 x 5 x 0.5 pulgadas, controles y un recipiente sellado para romper el vacfo. Este modulo cabe en un estuche de fibra de vidrio intemperizado de 24 x 24 x 12 pulgadas. La unidad pesa aproximadamente 23 kg, principalraente en razon del transformador y el estuche de fibra de vidrio. Para operar la unidad se requiere de una fuente de energfa externa, como por ejemplo una baterla de automovil (baterfa de almacenamiento de 12 V) o panel solar (14-45 W), y una solucion de alimentacion de salmwera diluida, 0.75 M NaCl. Cuando la salmuera diluida entra en contacto con las superficies catallticas de metales Grupo VIII de la celda electrolitica, se produce en el anodo una mezcla de oxidantes que Incluye cloro libre, hipoclorito, radicales libres de cloro y oxfgeno y ozono. Esta corriente de efluente del anodo se utiliza para tratar el agua contaminada. La corriente de efluente del catodo se elimina. Cuando la corriente del anodo se mezcla con 500 a 1,000 volumenes de agua contaminada, los oxidantes de corta vida matan a los microorganismos, destruyen los componentes organicos como fenoles, precipitan metales pesados corao oxidos y mejoran el color, olor y sabor del agua. El cloro proporciona un residuo de larga duracion para impedir que vuelvan a crecer las bacterias y permite verificar el tratamiento de agua mediante pruebas patron de concentracion de cloro. La Figura 1 presenta un diagrama del proceso. - O) 4-> 2 - 0) i -a <D c 4-1 c <u <u C cfl • H T3 >-i *-i 1 cd XI •H O X ° O o <U U XJ H CO CO cO O U w Q Pi < o M Q u <: < z> 1-1 < Q <: Q M tO 3 co CO <D -a c \o •H O CO U z (0 CO X I .-H CO 3 3 C > O a. a) i-l -H \co cj > o co XI <c H < X! cfl XI •H C 3 0) x> o u CO CJ OJ -a c \o Q) - H >~\ 3 O cr 3 C rH CO O 4-1 CO / \ u CO i-l CO •H 4-1 MO •H e O U OJ 3 DCfl OJ 4-1 >r-l i-H u u >c ai OJ Cfl •H CD .—1 O O 4-1 CO • H o. u o c •^ M c •H o. 01 4-> CO CO OJ 3 C C0\^ CO . H CO U 3 oo •H - 3 - 2. " POSIBLES APLICACIONES Esta unidad simple, pequetfa y resistente de tratamiento de agua puede utilizarse en muchas localidades ya que no necesita de una red de suministro electrico desarrollada, personal de mantenlmlento capacitado, surainistros quimicos pellgrosos o importados, nl tampoco de un apoyo industrial adyacente. Entre sus posibles aplicaciones podemos mencionar: - Localidad perrnanente remota, grupos de exploraclon m5vil, operaciones de rescate en desastres naturales, unldades railltares, instalaclones de embarcaciones marftiroas, y corao algicida en sistemas de agua refrlgerante. El tamaffo de la unidad puede adecuarse a la aplicacion deseada, pudiendo colocarse varios modulos en serie para aumentar el volumen de agua tratada. Las unldades pueden sacarse individualmente de la lfnea para su mantenlmlento, sin afectar la produccion. El raetodo es 100% efectivo contra —' ££ii> Legionella pneumophilia, Pseudomonas aeruginosa, quistes de Giardia y esporas de Bacillus subtilis. 3. PUNTO DE CONTACTO Para mayor informacion trataraiento de agua dirigirse a: relacionada a este metodo exclusivo Los Alamos Technical Associates, Inc. P.O. Box 410 1650 Trinity Drive Los Alamos, New Mexico 87544 E.U.A. t Atencion: H.F. Gram Telefono; (505) 662-9080 de PRIMER SEMINARIO INXERNACICNAL SOBRE EffiSINFBOCICN DEL AGUA POR OXIDANTES ME2CLAD0S MINISTERIO DE SALUD REPUBLICA DE PANAMA Ing. Franciscx) Osorio DESCRIPCICN DEL PROGRAMA: El Ministerio de Salud a trav£s de la Direcci6n Nacional de Ingenierfa Sa nitaria y Conservacioh es el responsable de dotar de agua potable a la po blaci6n rural de menos de 500 habitantes msdiante sistanas de acueductos o pozos pufolioos accionados con baifoas roanuales. Las ocrnumidades rurales de mayor poblacion y el area lirbana, son abastecidas por el Institute de Acueductos y Alcantarillados Nacionales (IDAAN). ' El programa de acueductos rurales del Ministerio contenpla que una vez construido el acueducto la oanunidad beneficiada sea la responsable de ad ministrar, operar y mantener el sistevna, limitandose el Ministerio de Salud a las responsabilidades de supervision y apoyo tecnico requerido por la ccrnunidad. Este mecanismo de trabajo se ha desarrollado coo. bastante exito en la Republica de Panam£ y debido a este se han podido construir ma's de 1000 sistemas de acueductos rurales en todo el pals, abasteciendo a mas de 340.000 habitantes del area rural cor. conexioh dcraiciliaria. De los 1000 sistemas construidos aproxoiitadamsnte el 90% utilizan agua sub terranea ccmo fuente de abasfcecindento, mediante pozos profundos o manantiales captados en su nacijnientp. El 10% restante utiliza agua superficial que en la mayorfa de los casos es tratada a travel de filtracich len ta antes de ser distribuida. Menos del 5% de los sistemas en operaci6n son dorados actualmente y los analisis de agua se hacen en forma puntual sin obedecer a un ve£ dadero programa de control de calidad del agua abastecida. EXPERIENCIA CON EL BQUIPO MQGGOD La OPS/CMS ha donado a la Fepublica de Panama1 (8) equipos MOGQOD can pletos con su correspondiente sal TNAS. Este equipo fug distribuido en la siguiente forma: (4) equipos para ser instalados por el IDAAN (4) equipos para ser instalados por el Ministe rio de Salud El Ministerio de Salud instal6 el 18 de noviembre de 1987 el primer generador de gases oxidantes con una capacidad de 1/2 libra de oxidan tes por dla en la ccmunidad de Loma Bonita, Provincia de PanamS. Esta ccmunidad se dedica mSs que nada a la ganaderia y la agricultura y por su cercanla a la ciudad de Panama1, parte de su poblaci6n trabaja en la misma. 1.- Caracterlsticas Principales del sisteroa de acueducto; Numero de conexiones = 65 Poblacion servida = 330 habitantes e Fuente de Abasto = Pozo profundo con forro de 6"0 Caudal de bombeo = 45 gal/min. (2.85 1/s) Capacidad de almacenamiento =4500 galones (17.0 m 3 ) 2.- Equipo instalado = bomba sumergible de 2 H.P. Red de distribucion = 1 km de radio aproximadamente en 2"0 PVC Instalaci6n, del equipo: El equipo rue" instalado siguiendo las indicaciones que aparecen en el manual suministrado, se utiliz6 una valvula de paso para crear una - 3 - presion diferencial y regula el vacio producido por el venturi. Hasta la fecha no se ha podido instalar un medidor de gases que permita conocer la cantidad de oxidantes prcducidos. La instalaci6n electrica se hizo de manera que el generador de oxi dantes sea controlado con la cajilla de la bcntba y sus controles de niveles. No hubo probleroas t£cnicos en la instalaci6n de este equipo. 3.- Calidad del agua cruda; El agua cruda es de buena calidad, ya que los analisis no presentaron bacterias coliformes, con una demanda de cloro de 0.5 mg/1 a una temperatura de 25°C. 4.- Funcionamiento del Equipo; La operaci6n del equipo se inici6 a diferentes amperajes para obtener el que se ajustase ma's a la producei6h diaria de agua, obteniendose un amperaje obtimo de 5 amp. para mantener un claro residual de salida de 0.8 a 1.0 mg/1. Con esta producci6n de gases se obtuvo en la red un cloro residual de 0.6 mg/1 en las casas ma's centricas a 0.3 en las viviendas mils alejadas. 5.- Ventajas obseryadas de la desinfeccidn con el equipo fPGGOD: - FScil instalacich - FScii operaci6n para el personal con poco adiestratramiento encargado de operar los acueductos rurales. - Mejor control en la dosificaci6n para obtener un cloro residual de seado, "cemparado con el clorinador por goteo. - 4 - - El equipo de 1/2 libra diaria se ajusta a las demandas diarias de agua de las poblaciones y a la calidad del agua abastecida por el Programa de Acueductos Rurales. ' ~ Dssventajas: Debido al poco tiempo que tiene el equipo IOGG0D de estar instalado y a la poca informacidn disponible sobre el mismo se desconoce lo siguiente: - Principales problemas de mantenimiento y reparaci6n de los mismos. - Dj.sponibilidad y cos to de repuestos, sobre todo la membrana semipermeable y los electrodos. - - Experiencias obtenidas trabajandp con corriente directa. Asuntos importantes de instalaci6n del fflOGGOD; Se ha querido resaltar el hecho de que debido a que la producci6n del pozo disminuye en la estacion seca y la bomba es controlada automSticamente por el control de niveles, se decidi6 que el equipo MDGGOD fuese controlado igiaalmente en forma autcmStica por este con trol, para evitar que siguiese produciendo gases en el interv^alo de parada del equipo que dura aproximadamente 10 minutos. Sin embargo, esto produce una entrada de corriente instantanea al transformador que se desconoce el efecto que pueda tener en el mismo a largo plazo. \ *** DESINFECCION, UTILIZANDO EL MOGGO *** Esta unidad de desinfecci6n fue instalada primeramente en un pozo con un gasto de 25 L.p.s., siendo muy elevado para la capacidad ' de la unidad ox i que se instald, e'sto se manifest6 en el residual de cloro m5x i mo que se alcanz6 e» la red, el cua I fue de 0.1 ppm.; aun con e^to, se lograron buenos resultados, ta I y como se m u e s — tran en el Cuadro No. 1 I os an^Nsis bacterioI6gicos del agua, an_ tes y despu^s de tratamiento a las 12 hrs. de funcionamiento. Por otra parte, en este lugar se tuv» problemas de taponami ento de la membrana y su funcionamiento era de unas 20 hrs., aproximadamente. El Moggo se cambi6 a otro lugar, donde se t ieneprob lemas de conta_ minaci6n, este pozo tiene un gasto de 12 L.p.s. y 240 Coliformes' Totales/lOO Ml., en este lugar sc presentaron problemas para la ' des i nf ecc i 6n, \a que la zona es alitnentada por dos pozos, y, el ' agua tratada Mega a una pequena zona, encontrSndose en estos Iugares, res i dua les' de cloro I ibre «le 0.2 p.p.m. y 0 de col'iformes' Totales/lOO Ml., los resultados st indican en el Cuadro No. 2. En esta parte el equipo dur6 en funcionamiento nueve dfas, se quit6' para darIe mantenimiento por presentar fuga. Actualmente se encuentra instalado en una pequena comunidad, con' un gasto de 2.7 L.p.s., 632 Coliformes Totales/lOO Ml. y 1 C o l i — forme JTefcal/lOO Ml.; para 6ptimo funcionamiento del equipo, se " instal6 una bomba de ayuda para veneer la presi6n y, como el Venturi es muy fr^gil, £ste fue sustituido por el inyector de un eqyj po clorador, con Io cual se ha teaido buen funcionamiento. • CO -J r ' 3E <: o o o o o o o o o O O O UJ CO UJ •< cc o < u_ H — • < CO • < -» h- cc o o o o o o o o ^ o o o o O O O O O CS • • • • • O O O O O O O O O o co UJ =3 CL CO UJ =3 a CO UJ * co o o o co cc UJ HX O Q O O O O o o o d c s o o o o o o o o o cc o -J o CO UJ < OS UJ H- CO < 00 cO o ae CO co o • CO LJ O CO co O a < tC -c o ze o 1— O O O uj y-, U» _J 3 z o Q£ CO UJ 2E CC CO O UJ -J UJ t- c o UJ Ct UJ 3 < u. * * CO •< tx. H (/) UJ =3 a£ CO < -J o o o o o o o o o o o OO O OO O O OO CS| -"4" f x CO r-< »H O O rx. c* oo M I T I 0 O rt H O ,~i r-t t x i-i o o o o o o • • • • • • o o o o o o O o "-teSOJCSlCSICSCSC^CM o o o o o o o o o 3 o o •< O I o • < =3 Cl CO UJ CC o o O t a Q • O • O • o o o o o ooooooo • o e^ • • • • • oo\ • • o o o o o o o o o _1 o • CO I DESINFECCION DEL AGUA MED I ANTE EL MOGGO : La unidad oxi 2 lb. de capacidad es probada en (a salida de un tanque de almacenamiento con un gasto de 17 — l.p.s., <?sta agua tiene una concentrac i6n bacteriana -de 86 col iforires total es/ 100 Ml y 0 de col iforir.es fecales/100 Ml. Este tanque abastece a una poblacidn de 12,000 habitantes. Se encontro" que el agua con un residual de cloro I ibre' de 0.2 PPM a la sal ida del tanque I Iega hasta el punto' ma's alejado de la red de d istr ibuc i6n sin cloro res i dual, tenie"ndo una el iminaci6n bacteriana del 98 % . \ • co -J UJ 3E -J " ^ • < O O C UJ ^ u. <fi UJ s < Qi V} o O UJ <t U. -1 t< -J hOC o O 1h- o — • < o o o o o o o o CN • f) n O H O O O »-< C-J r-t • • o o o o o <: _) <: rs o * * < rs o to UJ OL o o o o O n fO i H c^ T t O m * m W1M N M fO o o o o o o o o o o o o o * • • • • o o o o o o o o o o o o o o o o o o o oo o o Q: O —J o O <r CD V) < z < • (/) CO O O O O UJ -" U. <c < 3: (/; UJ s L/) C£ (/) O UJ b 1 CC — •< -J H »— »~i ON ON LO O O O ON T 4 C1 U-» * 0 t o r^- LO CI »-• »-t t-H —I o o o o m VO VO <s| (M CI «-"t o „J < o — <: CO UJ Ct o ct o _J o o o o o o o o o o o o o o o o o o o o o o • • • * * o• o• o• o• o• o oo o o o o o o o <: z o M CN o o o o o o CI GO C-l ro (A 3= T—* <H •—1 ^ r a CJ o o o ON O CO C4 fi OH ^3 t o oo O m < c CJ Ho C_) o < CO <: % * 0 SAN A N T O N I O _J UJ S -J DEL MARQUES o <. S O o z CO o »z •< _) _J cc o CD ~ CM r*5 <: • < •< z o M • < Z o NJ z o M PROGRAMA DB VIGILANCIA Y MBJORAMIBHTO DB CALIDAD DB AGUA FORttULABIO DE IESPECCIOUES EURALES SISTEMAS DE GBAVEDAD SIN TRATAMIEMTO Comunidad Fecha / GufaHoja / / GUI A PARA EL LLENADO DEL FORMULARIO 1. PLANIFICAR para hacer oor lo menos: -una visita por ano a ceda comunidad -y una visita adicional por ano, por cadauna de 18s siguientes condiciones: -cuenta con un sistema de bombeo -cuenta con una planta de tratamiento -tiene un poblacion service de m8s de 500 nab. 2. NOTIFIQUE a la comunidad de su visita con anticipacion NUNCA hacer mfc que un inspection por dia 3. HAQA su inspeccion y COMPLETE el formulano en presencia de un representante del pueblo (autoridad deagua). El(los) debe(n) ffrmar abajo. 4. LLENAR el formulario con letra de imprenta 5. CONTESTE todo el formulario. -para contestar si, marque asi: si ( x ), no ( ) -para contestar no, marque est: si ( ), no ( x ) -cuando haya varias posibilidades, marque la apropiada ( x ) -para numeros, nunca marque ( - ) 6 ( x ), siempre coloque 0 6 el valor correspondiente. USE los espacios de "Observaciones" y "Esquema Sencillo" para clarificar o poner otra informacion de importancia 6. Al dia siguiente- complete una couia del formulario para enviar a la BRD-Region Central a fin demes(amaquina) - complete dos formularies de informe al pueblo (a maquina) y ENVIELOS (una copia a la BRD* yunacoplaal pueblo) (*BRD = Base Regional de DITESA) Determlnac16n de la Potencta de Cloro en Polvo 1.. Tome una muestra de unos gramos en una bolsa plastica y guardelos en un lugar oscuro, frio y \ seco hasta el momento del analisis. Siempre haga el analisis antes de las 48 horas. 2. nida 1 g del polvo con la balanza de precision. 3. Disuelvalo en ! litro de agua limpia (destilada si es posible). 3. Tome5mldelasoluci6nenun8pipetayecheloen 1 litro da agua, mezclebien. 4. Chequee la concentracion de cloro total en el agua con el comparador(=x) mg/1 5. Potencia (%) - concentracion (x) x 200 PROGRAMA DE V I G I L A N C I A Y MEJORAMIENTO DE C A L I D A D DE AGUA , Hoja Comunidad Fecha / GST-1 / INSPECCION Fechade Inspection Inspeccion hecha por 1 2 DelPVMCA- / / (base) LUGAR Comunidad Distrito Provlncia Departamento aqua ooblacion total No. Usuarios/poblacion servicfe habs ) habs ) habs ) habs ) ) habs habs habs If III Nombre del Barrio del pueblo con servicio de si( ),no( si( ).no( si( ),no( s i ( ),no( si ( ).no( TOTALES Codlgo GENERALIDADES Numero de horas de viaje desde la base del PVMCA a la comunidad= distancia= por: carro( ) , t r e n ( ),moto( ).caballo( ),otro= horas Km Ministerio de Salud: Puesto ( ),Centro( ), Botiquin Comunal ( ),otro= que distanciadel centro del pueblo Km, Medico( ),Enfermera( ),Sanit8rio( ),Promotor( Hay una escuela en 18 comunidad? si ( ), no ( ) Hay luz en la comunidad? si ( ), no ( ) FIRM AS Firmas de los Inspectores del Equipode Vigilancia:- 1 2 NOMBRE NOMBRE CARGO CARGO... Firm8s de los representantes del pueblo 1 2 NOMBRE NOMBRE CARGO CARGO horas de viaje ),otro = PROGRAMA DE VI6ILANCIA Y MEJORAMIENTO DE CALIDAD DE AGUA Hoja GST-J Comunidad Fecha / / FUENTE DE AGUA Tipode fu9nte: manantial captado directo ( ), lago/laguna( ),pozo( ), no ( ),riachuelo ( ), quebrada ( ), canal de regadio ( ), otro = Nombredelafuente Contaminacionde lafuentedeagua: mineria( ), letrinas( ), basura( ), ganado( ), lavanderia( ), animates ( ),humanos( ),otros = Cantidad de agua existente en la fuente = litros por segundo (Ver Hoja 2) es la cantidad usual (todo el dia y todo el ano): si ( ),no( ). (si no, EXPLIQUEen Observaclones) avec8s, no hay agua: si ( ),no( ) -cuantos di8S al ano Cuando -cuantas horas al dia Cuando Se utilize para irrigacion: si ( ),no( ) La fuente esta ubicada en terrenos de Observnciones CAPTACION Manantial captado en directo v proteqido si ( ),no( ) Estasellado? si ( ),no( ),otienet8paremovible: si ( ),no( ) Esta" seguro(bajo Have)? si ( ),no( ) -con aletas: si ( ), no( ) -consello (losa)de protection atras: si ( ),no( ) -con tapa sanitaria: si ( ), no ( ) -la protection esefectiva: si ( ),no( ); (si no.CXPLIQUC en Observaciones) -con cerco 0 muro: si ( ),no( ) que puede evitar el ingresodeanimales: s i ( ),no( ) -con canaleta de desvio para agues superficiales: si ( ),no( ) -cuantos metros de la captation metros -que puede prevenir el ingreso de lss aguas: si ( ), no ( ) Cantidad de aqua que inqresa al sistema = litros por segundo Puntodeaforo = Existe control de flulo: s f ( ),no( ) ' -por vertedero triangular: si ( ) , n o ( )de °(angulo) -por vertedero rectangular: si ( ) , n o ( ) -de que materiales _ Existe un medio para evacuar el exceso de fluio: si ( ), no ( ) -por tuberia de rebose vertical ( ) de pulgadasde dISmetro -u horizontal ( )de pulgadas de diametro -0 aliviadero ( ) de centimetros de largo -se puede evacuar el 10055 del ingreso: si ( ), no ( ) Existe una tuberia removiple para limpieza: si ( ),no( ) 0 valvule de purga: si ( ),no( ) Alasalida: -existe unacanastilla: si ( ), no ( )omalladeprotecci6n: s i ( ),no( ) -existe un8 valvule de control desalida( ) Observaciones Acetones Requeridas PROGRAMA DE VIGILANCIA Y MEJORAMIENTO DE CALIDAD DE AGUA Hoja 6ST-5 Comunidad Fecha / / RESERVORIO Caja de valvules: Esta sellada: si ( ),no( ) o tiene taps: si ( ),no( );segurobajollavesi ( ),no( ) hay problemas con las valvules: si ( ),no( )(ESPECIFICARLOSenObservaciones) puedeevacuarse.aguade la cajade valvules: si ( ),no( ). {por unhuecoal fondo( )opor fondo de grava ( ) o por otro ruta= } tiene rebose si ( ),no( ); tiene valvule delimpieza si ( ),no( ) Boca de inspection: Existe: si ( ), no ( ); protegida por tepa sanitaria: si ( ), no ( ) Esta sell8da con concreto: si ( ),no( ),osegurobajo Have: si ( ),no( ) El Tanoue Tiene ventilador(es): si ( ),no( ); con boca hacia abajo: si ( ),no( ) y protegido por malla: s i ( ),no( ) Puede entrar el aqua de lluvla: si ( ),no( ) o de la superficie: si ( ),no( ) Tiene fuoas (el tanque): si ( ), no ( ) Dimensiones Interiores: Largo= m,ancho= m, diemetro= m.alturadepiso a rebose = m, Volumen = m3 Observsciones Accioncg Requeridas LINEA DE ADUCCION ( L o n g i t u d del Reservorio al Pueblo) Longitudaproximada = Km Diametro = pulgadas Material: PYC ( ), FoOo ( ), Eterni* ( ), otro = Hay fuqas: si ( ) , n o ( ); cuantas (ANOTARLAS en el esquema sencillo) Otros problemas: si ( ), no ( ); cuales (ANOTARLOS tambien) Cuent8 con caia(s) rompe presion: si ( ), no ( ); cuantas (ANOTARLAS) -cuenta con tapa sanitaria: si ( ), no ( ) -cuenta con rebose: si ( ) no ( ): -portubo( )oaliviadero( );8decuadopar8evacuartodo el rebose: si ( ),no( ) -protegido (p.e. por malla) contra el ingreso de cuerpos extranos: si ( ),no( ) -se saca agua de la(s) caja(s): si ( ), no ( ): -paraconsumohumano( )oparaanim8les( ) o para irrigation ( ) Cuenta con valvula de aire: si ( ), no ( )Cuantas (ANOTARLAS en el esquema) Cuenta con valvula de purge: si ( ), no ( ), cuantas (ANOTARLAS en el esquema) Observsciones (ANOTAR si los componentes no funcionan) Acciones Requeridas PROGRAMA DE VIGILANCIA Y MEJORAMIENTO DE CALIDAD DE AGUA Hoja 6b'-? MUESTREAR:siempre -captacion (cada una) -reservorio(cadauno) -despues de cada unidad de tratamiento -antes y despues de clorecion (cuando hay) -en la red - Piletas Publicas, 5 6 20X unidades (el mayor) - Conexiones Domiciliarias: entre 5 y 10X de ellos (tomarlos en V5 cruces prlncipales y fines de la red) edemas, a su discrecion -fuente usada -otras fuentes -caja de reunion -C8J8S rompe presiones -mas lugares en la red VOLUMENES para a n a l i z a r Seleccionar los volumenes tomando en cuenta la parte del sistema y/o estado de contam inacion. Tipo de muestra Canal deRegadio.Rfos Lagos remotos, riachuelos remotos, quebradas P020S protegldos, m8nantiales protegldos Aguas parcialmente tratadas Aguas tratadas, reservorios, redes de distribucion Volumen para analizar Posible Normalmente 50ml 10ml 100,10ml 50ml 50ml 100ml 0.1 6 1 6 100ml 10 6 50ml 50ml 100ml Resultados de Analisis: FUENTE do i a J H o r a J A a p e ^ iSaboridez i l t b r e i t o t a l : fiC MUESTRA. : C o l o r : UT : m 9f\ : m 9 / j :' N; •iuctiv jf«?.?A... !uS/cm" 'i/jPOfn.l PROGRAMA DE VIGILANCIA Y MEJORAMIENTO DE CALIDAD DE AGUA INSPECCIONAR -las casas donde se hace analisis -y la mitad de este numero de ellas sin agua Inspeccl6n DomJcJIfarla (con Agua) (usar lasmismsscases del analisis de agua) No Disposicion de Basura Proximidad de Animates domesticos alimento entierro querns boter cerca botar lejos ;n huerlo al lado aparte no tiener que animales a la casa dela casa ?n la casa iela casa animates animales 1... 2... 3... A... 5... 6... 7... 8... 9... 10. 11. 12. ( Inspeccfdn Casera (Sin Agua) firoxUnlM dt Animates oomlslicos No Di'sposfcioo C*e Basura sllmento enllerro !)uema joUr cerct txjlar lejos en huerto si lado iparle no tienen que" animates animales snlmales l l t C I M d«la casa en U CMS* ilia casa .elrlna seusa lozade seve xncrelo laps limpi lx\i\e lipo 1 2 3 4.. 5.. 6.. 7 8 q 10 11 12 ••• i • - ^j • — ....*..................~ — ..... z:=: E _._ \ \ : : : : Hoja GST-9 Letrina Existe Tipo S8US8 lozade con seve concreto tape limpia > • Recoleccion personal Cfopsearefowclgwa. iPilcta \ ozo menentialirloo psmidh buehte pui6i buevolumen recipiente pare Do^xfctoquarda Public* chueli cislernjpviajesdiarfdloshace CapacidadjQuSmaleriej] cootapajcongrifo porviaje(lilros) recoleccion