Measuring the Benefit of a State of the Art Water Treatment Facility to

Measuring the Benefit of a State of the Art Water Treatment Facility to

A WH ITE PA PE R BY V EO LI A WATE R
CONSOL Energy, Inc.
Measuring the Benefit of a State of
the Art Water Treatment Facility to the
Monongahela Basin
WATE R I M PACT I N D E X
APPLIC ATION
Innovative wastewater treatment is critical to ensuring a future with sufficient
and clean water, a robust and secure economy, and an ever-improving quality
of life. These goals are only attainable if growth and improvement, and the
accompanying strain that they place on limited natural resources, is supported
with sustainable practices.
Introduction
This case study reviews how CONSOL Energy
Inc., a leading energy sector company,
partnered with Veolia Water, one of the
world’s leading water treatment services and
technologies companies, to develop a state-ofthe-art mine water treatment facility.
Project Description
CONSOL’s mine water treatment facility is located near
Mannington, West Virginia, and will treat mine water
from its Blacksville #2, Loveridge, and Robinson Run
mines. Total design capacity is 3,500 gallons per minute
(gpm) for a centralized facility. The system applies
chemical precipitation, reverse osmosis and thermal
technologies that include:
The facility integrates chemical precipitation, reverse
• pretreatment with softening and precipitation
osmosis and thermal technologies developed by Veolia
chemistry
to maximize the recovery of clean water for return to the
• clarification and filtration polishing
environment. A design-build-operate project delivery
• sludge dewatering
approach is used that allows CONSOL to focus on its
• reverse osmosis (RO) and return of the purified
core business while ensuring facility performance to the
permeate stream to the river basin
highest standards. The result is an enhancement of water
• pretreatment of the RO reject with softening and
resources in the Monongahela River basin in Northern
precipitation chemistry
West Virginia, which is the exact intent of sustainability,
• evaporation of the softened stream and return
to protect the environment while
of the distillate to the river basin
supporting economic and quality of
“ Partnering with
•
crystallization of the brine stream
life needs.
Veolia on this
• crystallizer solids dewatering
project provides
To provide an accurate measure of the
This combination of technologies results in
benefit provided by the facility, the
CONSOL with a
zero liquid waste as well as solids residuals that
Water Impact Index was applied. The
turnkey system
are safe for landfill, as shown in the block flow
Water Impact Index is a comprehensive
coupled with
diagram below. More importantly, it improves
water footprint indicator developed by
proven operator
effluent quality such that it not only meets the
Veolia Water. It integrates all the aspects
capabilities”
regulatory requirements, but leads to overall
of the water cycle, including water
– Katharine A. Fredricksen
improvement of the local water resource as will
quality, water availability in the local
CONSOL ENERGY
be described below.
environment, and volume to provide
an accurate measure of environmental
Product Water
benefit.
Aeration
This case study describes
several elements of
CONSOL’s mine water
treatment project, including
the treatment process, an
introduction to the Water
Impact Index, and the
approach used to measure
the benefit that treatment
delivers to the Monongahela
River basin.
Raw Water
Feed
Tank
CONSOL’s mine water
treatment facility near
Mannington, West Virginia
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Crystallization Tank
Clarifier
Multimedia
Filter
R.O. Feed
Tank
R.O.
AL Precipitation
Evaporator
Feed Tank
Sludge Holding
Tank
Crystallization
Tank
Dewatering
Equipment
Clarifier
Evaporator
Solids
Crystalizer
Feed Tank
Solids
Dewatering
Equipment
Crystalizer
Final
Effluent
Tank
Technological innovation is not the only special aspect
of this project. Cutting edge thinking also underscored
CONSOL’s approach to project execution. After reviewing
many options CONSOL selected a design build operate
(DBO) project delivery approach. The approach provides
a complete scope of services and maintains long term
responsibility for performance through a single solutions
supplier, in this case Veolia. The cornerstone of DBO
project delivery is Veolia’s ability to take full responsibility
for design, installation, and performance. DBO services
are provided to maintain performance at the design
basis, including capacity, effluent quality, availability,
design build expense, operations expense, and project
schedule. On the performance end, Veolia provides a
dedicated management, operations and maintenance
staff providing 24/7 coverage, operations, preventive
and corrective maintenance, and chemicals and residuals
dewatering. Together these commitments are delivered
through a performance guarantee that is contractually
supported by Veolia for the complete term of the project.
CONSOL is protected from any shortcomings in plant
performance, which are now the responsibility of Veolia.
Assessing the Effect on the Water Resource:
the Water Impact Index
Most water footprint assessments focus on volume, a
valid indicator to raise awareness but not necessarily
sufficient to represent the impact on a water resource. In
this particular case, measuring only water quantity would
be misleading in that influent and effluent quantities are
nearly equal, as depicted below. The influent volumes
are projected to be 3,505 gpm or 1.840 billion gallons per
year, and the corresponding effluent volumes are 3,490
gpm or 1.835 billion. This is essentially the same amount of
water as CONSOL currently discharges from these mines.
Consequently, an assessment based on volume alone does
not accurately reflect the benefit to the water resource
from this project.
Recognizing that water footprint assessments based on
volume alone were no longer adequate, researchers at
Veolia embarked on the development of an assessment
tool that incorporates multiple variables that are
important to the viability of the local water resource.
In addition, Veolia wanted to develop an indicator that can
Recognizing that water footprint assessments based on volume alone were no longer
adequate, researchers at Veolia embarked on the development of an assessment
tool that incorporates multiple variables that are important to the viability of the
local water resource. The result of Veolia’s effort is the Water Impact Index.
Veolia Integrated Solution
Treatment Facility
Raw Water
Feed
Tank
Blacksville No. 2
3505 gpm
Loveridge
Robinson Run
Product Water
Aeration
Crystallization Tank
Clarifier
Multimedia
Filter
R.O. Feed
Tank
R.O.
AL Precipitation
Evaporator
Feed Tank
Sludge Holding
Tank
Crystallization
Tank
Dewatering
Equipment
Clarifier
Final
Effluent
Tank
3490 gpm
Evaporator
Solids
Crystalizer
Feed Tank
Solids
The results of
a volume-based
measurement
Dewatering
Equipment
Landfill
Crystalizer
•
Mannington
Monongahela
Basin
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The Water Impact Index
• Water Quality
• Volume of
water used –
withdrawn and
released
+
The Water Impact Index is expressed in gallons
equivalent. This is a mathematical representation of the
three parameters and is not a true gallon of water. While
this concept can appear abstract at first, it provides an
optimal tool for decision making purposes. The lower the
Index, the lower the impact to local water resources.
A negative value implies that the process benefits
local water resources. The Index can also be converted
back to actual gallons. Using this information, the user
of the tool has an idea of what needs to be addressed to
lower the impact.
The methodology is elegant in its simplicity. In essence,
the Water Impact Index is a mass balance equation that
compares the quantity, quality, and stress factor of the
withdrawn water to the same parameters of the released
water (see below). The equation multiplies the three
values of volume, stress index, and quality index in the
water volume withdrawn, and then subtracts the product
of the same three factors for the water volume released.
To provide the user with a better understanding of the
tool, the following characteristics of the Water Impact
Index are provided.
• An increase in the volume withdrawn increases the
Index
There are several key points to realize in the mathematics.
First, the quality index is based on a component of
concern and the same one is used on both sides of
the equation. Cref is a reference concentration for this
component. It corresponds to the concentration that
should be reached to ensure protection of the local
j
j
l
Volume Withdrawn
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• An increase in the volume released decreases the Index
• An increase in the stress index of water withdrawn
increases the Index
• An increase in the stress index of water released
decreases the Index
Stress Index
Quality Index
∑ [W x WSI x min [1; Cref
C
j
• Water quality –
withdrawn and
released
water resource for its intended uses. C is the actual
concentration of the component in the withdrawn or
released water. Second, the stress index is a dimensionless
value between 0 and 1 that reflects the local scarcity of
water. The stress index takes into consideration local
water use and availability, seasonal variations in fresh
water availability and storage capacity. These values have
been mapped for most of the world by Pfister, Zurich
in 2009.
With the Water Impact Index, the physical water quantity
balance for any product or process is weighted by a quality
index and a water stress index, as seen above. The water
quality index provides a means of measuring changes
in water quality and the value of water treatment. The
water stress index accounts for the level of stress on
the resource. Together these factors, through the Water
Impact Index, provide a means of measuring the full water
impact. Indirect impacts from the production chain such
as water use from energy, raw materials, chemicals, and
waste generation are also incorporated into the balance.
WIIX =
+
• The Water Stress
Index
• Local condition
of resource
be used to support decision-making and communication,
among other uses. The result of Veolia’s effort is the
Water Impact Index, a comprehensive water footprint
indicator that integrates all aspects of the water cycle,
including water quality and availability in the local
environment.
Water Impact Index
Equation
QUALITY
STRESS
VOLUME
l
j,l
Cref
R
x
WSI
x
min
1;
∑
[
]]
[ C
–
k
k
k
Volume Released
l
l
k,l
]]
METHODOLOGY
• An increase in the quality
THODOLOGY
METHODOLOGY
THODOLOGY
index of the water withdrawn
A new metric for assessing water impacts.
Indirect Water Impacts
A new
metric
assessing
water impacts.
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for
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METHODOLOGY
Direct Water
Impact Index
•
increase
in the
index water impacts.
AAn
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assessing
of the water released decreases
the Index
Direct Water
Because the methodology is
Direct
Impact
Index
Direct Water
Direct
Water
rooted
in life
cycle
concepts and
Impact
methodologies,Index
it also takes into
Impact
Impact Index
Indirect Water
Direct WIIX
Impact Index
account indirect water impacts
GY
LOGYMETHODOLOGY
ofMETHODOLOGY
any process from “cradle to
ssessing
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impacts.
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indirect
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assessing
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Indirect
water
impactWater
commonly include
Indirect
Water
chemicals
and
Impact
Index
Impact electricity
Index consumed
Indirect WIIX
in the treatment process. The
Indirect Water
EnergyEnergy
Indirect
Chemicals
calculation is based on quality and
Impact Index
Index
Impact
stress indexes in the local area in
Direct
Water
ter
which theDirect
electricity Water
is generated
Energy
Energy
Impact
Index
or the
chemicals
are produced.
Impact
Index
dex
Chemicals
Energy
WhileChemicals
calculating the direct water
Waste
impact
is done by utilizing the
Chemicals
Water Impact Index equation, it
becomes cumbersome to calculate
of the chemicals and energy used to run the plant. The
all of the indirect impacts with the
Chemicals same approach. To address this, a database of indirect
variables input into the equation for the manufacture and
Indirect
Water
Water
rChemicals
Indirect
Water
transport of chemicals assumed a West Virginia source.
water impact indexes is used. The calculations can be
Impact
Index
dex
Impact
Index
The variables used for electricity generation assumed an
done
for all steps
in the life cycle of products and services
overall average for the U.S.
and combined to determine a very comprehensive and
Energy
Energy
Energy
Energy
informative value.
Results of Analysis
The Water Impact Index can now be applied to evaluate
the benefit of CONSOL’s mine water treatment facility
Chemicals
on Chemicals
the local
Monongahela River basin. To begin, the
boundary conditions were set to the influent that feeds
and the treated effluent that is discharged from the
mine water treatment facility as shown on page 3. The
boundary limits provide a water withdrawn value of
1.840 billion gallons per year and water released value of
1.835 billion, nearly identical. The analysis uses chloride
as the component of concern in both the withdrawn
and released streams; chloride is the parameter that
drove the design of the treatment facility. The reference
concentration used for chloride was 230 milligrams per
liter (mg/l) based on a water quality standard published
by the state of West Virginia for the protection of aquatic
life. Both the withdrawal and release occur in the same
locale in regard to stress factor index. Accordingly the
same value of 0.0229 was used on both sides of the
equation. Finally, for indirect inputs, it was assumed
that the majority of the impact is related to the life cycle
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Waste
Was
Examining the calculation results we first see that for
the withdrawal part of the equation the direct index is
relatively small at 6.4 million gallons eq/yr., as shown
below. This is due to the relatively low quality (high
chloride concentration compared to the reference
Waste
concentration) of the water that is withdrawn.Waste
Calculation Results
Water withdrawn
Water released
Indirect WIIX
Total WIIX
10
5
MG eq/year
Applying the Water Impact Index to the Mine
Water Treatment Facility
Waste
6.4
0
4.8
-5
-10
-15
-20
-25
-30MG eq/year
-30.8
-35
-42
-40
The lower the
WIIX value,
the greater
the benefit
to the water
resource.
-45
-50
Water withdrawn
Water released
Indirect WIIX
The net impact is -30.8 million gal eq/year,
delivering a positive benefit to the environment
www.veoliawaterna.com
Note that withdrawing water from the ecosystem always
increases the Water Impact index.
The calculation for water released is more telling.
Although the volume is nearly unchanged between
withdrawal and release, the significant improvement in
the quality index dramatically reduces the direct index
to -42 million gallons eq/yr. The quality index, or ratio of
reference concentration to actual, goes from 0.15 for the
influent water quality to a value of 1.0 for the effluent.
Note that the quality index is limited to a value of one
even if the quality of the water released is better than
the quality required (the reference concentration), which
is the case here. Since the larger multiple is on the right
side of the equation, doing the mass balance subtraction
leads to a negative value for the index. Recall that the
lower or more negative the Water Impact Index the
greater the benefit to the water resource, in this case
the Monongahela River basin. Finally the indirect water
impact associated with the chemicals and electricity
consumed by the treatment facility is 4.8 million gallon
eq/yr, which is mostly due to the electricity used. The net
Water Impact Index, depicted graphically on page 5, is
-30.8 million gallon eq/yr.
What does all of this mean? Recall we noted that the
Water Impact Index can be converted to “real” gallons by
backing the stress index out of the equation. In doing so
the index value of -30.8 million gallon eq/yr translates to
a net volume of 1.3 billion gallons of high quality water
returned to the Monongahela River basin on an annual
basis. By installing this treatment facility, CONSOL is
making the water available to support other uses and
contributing to an overall improvement in water quality
in the basin.
Using this approach, the water withdrawn for treatment
has a value of 6.4 million gallon eq/yr in comparison to a
value of -42.0 million gallon eq/yr for the water returned.
While the volume of water for both streams is roughly the
same, the improved quality of the returned water brings
more value to the basin than the water that is withdrawn,
which is of much lower quality.
The indirect water impact from the use of chemicals and
electricity at the treatment facility is 4.8 million gallon
eq/yr which provides a net impact of -30.8 million gallon
eq/yr and delivers a positive impact to the Monongahela
River basin. The water impact can be converted back
into “real” gallons by backing out the stress index
used in the calculation, which converts the index back
to 1.3 billion gallons of high quality water supplied to
the Monongahela River basin each year. The result is
that CONSOL’s Treatment Facility delivers a positive
environmental impact back to the Monongahela River
basin.
With over 9,000 employees, CONSOL Energy Inc.
(NYSE: CNX) is the leading diversified energy producer
headquartered in the Appalachian basin. Named one of
America’s most admired companies by Fortune magazine,
CONSOL Energy produces both natural gas and high-BTU
coal. Together, natural gas and coal fuel two-thirds of the
nation’s power.
Veolia Water, the water division of Veolia Environnement,
is the world leader in water and wastewater services
and technological solutions. Its parent company, Veolia
Environnement (NYSE: VE and Paris Euronext: VIE), is the
worldwide reference in environmental services. With more
than 315,000 employees, Veolia Environnement recorded
annual revenues of $38 billion in 2011.
Concluding Summary
In conclusion, the objective of measuring the benefit
of CONSOL’s mine water treatment facility to the
Monongahela River basin has been achieved through the
use of the Water Impact Index. A simple measure of the
volume of water withdrawn and returned to the basin
provides little insight into the true benefit that treatment
provides. To expand on existing volume-based water
measurement tools Veolia developed the Water Impact
Index, a comprehensive water footprint indicator that
integrates all the aspects of the water cycle, including
water quality and availability in the local environment.
In addition to volume, the Water Impact Index adds a
quality index and local stress index to measure the impact
of water withdrawn and released back into the local
environment. The Index also takes into account indirect
water impacts associated with chemicals and electricity
consumed by the treatment facility.
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