An Industrial Water Impact Index case study - Veolia Water Solutions ...

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The Water Impact IndexVOLUME• Water Quality• Volume ofwater used –withdrawn andreleased+STRESS• The Water StressIndex• Local conditionof resource+QUALITY• Water quality –withdrawn andreleasedbe used to support decision-making and communication,among other uses. The result of Veolia’s effort is theWater Impact Index, a comprehensive water footprintindicator that integrates all aspects of the water cycle,including water quality and availability in the localenvironment.With the Water Impact Index, the physical water quantitybalance for any product or process is weighted by a qualityindex and a water stress index, as seen above. The waterquality index provides a means of measuring changesin water quality and the value of water treatment. Thewater stress index accounts for the level of stress onthe resource. Together these factors, through the WaterImpact Index, provide a means of measuring the full waterimpact. Indirect impacts from the production chain suchas water use from energy, raw materials, chemicals, andwaste generation are also incorporated into the balance.The methodology is elegant in its simplicity. In essence,the Water Impact Index is a mass balance equation thatcompares the quantity, quality, and stress factor of thewithdrawn water to the same parameters of the releasedwater (see below). The equation multiplies the threevalues of volume, stress index, and quality index in thewater volume withdrawn, and then subtracts the productof the same three factors for the water volume released.There are several key points to realize in the mathematics.First, the quality index is based on a component ofconcern and the same one is used on both sides ofthe equation. Cref is a reference concentration for thiscomponent. It corresponds to the concentration thatshould be reached to ensure protection of the localwater resource for its intended uses. C is the actualconcentration of the component in the withdrawn orreleased water. Second, the stress index is a dimensionlessvalue between 0 and 1 that reflects the local scarcity ofwater. The stress index takes into consideration localwater use and availability, seasonal variations in freshwater availability and storage capacity. These values havebeen mapped for most of the world by Pfister, Zurichin 2009.The Water Impact Index is expressed in gallonsequivalent. This is a mathematical representation of thethree parameters and is not a true gallon of water. Whilethis concept can appear abstract at first, it provides anoptimal tool for decision making purposes. The lower theIndex, the lower the impact to local water resources.A negative value implies that the process benefitslocal water resources. The Index can also be convertedback to actual gallons. Using this information, the userof the tool has an idea of what needs to be addressed tolower the impact.To provide the user with a better understanding of thetool, the following characteristics of the Water ImpactIndex are provided.• An increase in the volume withdrawn increases theIndex• An increase in the volume released decreases the Index• An increase in the stress index of water withdrawnincreases the Index• An increase in the stress index of water releaseddecreases the IndexWater Impact IndexEquationStress IndexQuality Index∑[WIIX = W x WSI x min [ 1; Cref l]] – j j l [ R x WSI x min [ k k ljC j,l∑k1; Cref l]] C k,lVolume WithdrawnVolume Released4A WHITE PAPER BY VEOLIA WATER
HODOLOGY• An increase in the qualityindex of the water withdrawnincreases the Indexmetric metric for for assessing water water impacts. impacts.METHODOLOGYirect Watermpact Indexhemicalshemicals terMETHODOLOGY• A An new increase metric in the for quality assessing index water impacts.of the water released decreasesthe IndexIndirect Water ImpactsA new metric for assessing water impacts.Direct WaterBecause the methodology isrooted Impact Direct in life Index cycle Water concepts andmethodologies, Impact IndexIndirect Waterit also takes intoDirect WIIX Impact Indexaccount indirect water impactsof METHODOLOGYany process from “cradle tograve.” A new Considerations metric for for indirect assessing water impacts.water Indirect impact commonly includeIndirectWaterWaterchemicals Impact Impactand Index electricityIndexconsumedIndirect WIIXin the treatment process. TheEnergy Energy Chemicalscalculation is based on quality andstress indexes in the local area inDirectwhich the Direct Waterelectricity Water is generatedEnergy Energyor the Impact chemicals Impact Index are produced. IndexEnergyChemicalsWhile calculating the direct waterChemicalsWasteimpact Chemicals is done by utilizing theWater Impact Index equation, itbecomes cumbersome to calculateall of the indirect impacts with theof the chemicals and energy used to run the plant. Thesame approach. To address this, a database of indirect variables input into the equation for the manufacture andIndirect Indirect Water Waterwater impact indexes is used. The calculations can be transport of chemicals assumed a West Virginia source.done Impact Impactfor all steps Index Indexin the life cycle of products and services The variables used for electricity generation assumed anand combined to determine a very comprehensive and Energy overall average for the U.S.EnergyEnergyEnergyinformative value.OGY Y METHODOLOGYsessing r assessing A new water water metric impacts. impacts. for assessing water impacts.ndirect Watermpact IndexerexexApplying the Water Impact Index to the MineWater Treatment FacilityThe Water Impact Index can now be applied to evaluatethe benefit of CONSOL’s mine water treatment facilityon the local ChemicalsChemicals Monongahela River basin. To begin, theboundary conditions were set to the influent that feedsand the treated effluent that is discharged from themine water treatment facility as shown on page 3. Theboundary limits provide a water withdrawn value of1.840 billion gallons per year and water released value of1.835 billion, nearly identical. The analysis uses chlorideas the component of concern in both the withdrawnand released streams; chloride is the parameter thatdrove the design of the treatment facility. The referenceconcentration used for chloride was 230 milligrams perliter (mg/l) based on a water quality standard publishedby the state of West Virginia for the protection of aquaticlife. Both the withdrawal and release occur in the samelocale in regard to stress factor index. Accordingly thesame value of 0.0229 was used on both sides of theequation. Finally, for indirect inputs, it was assumedthat the majority of the impact is related to the life cycleResults of AnalysisExamining the calculation results we first see that forthe withdrawal part of the equation the direct index isrelatively small at 6.4 million gallons eq/yr., as shownbelow. This is due to the relatively low quality (highchloride concentration compared to the referenceWasteconcentration) of the water that is withdrawn. WasteMG eq/yearCalculation Results1050-5-10-15-20-25-30.8 -30MG eq/year-35-40-45-50METHODOLOGYA new metric for assessing water impacts.6.4Direct WaterImpact IndexWater withdrawnWater released-42Indirect WIIXTotal WIIX4.8Water withdrawn Water released Indirect WIIXThe net impact is -30.8 million gal eq/year,delivering a positive benefit to the environmentWasteThe lower theWIIX value,the greaterthe benefitto the waterresource.WasteWas5A WHITE PAPER BY VEOLIA WATERwww.veoliawaterna.com
Page 2 and 3: Innovative wastewater treatment is
Page 6: Note that withdrawing water from th

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