Technologies and Costs for Removal of Arsenic From Drinking Water

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EPA has established water quality criteria under authority of the Clean Water Act. For watersused for fish consumption, the ambient water quality criterion for arsenic was set at 0.14 Fg/L. If awater source is also used as a source of drinking water, the arsenic limit is reduced to 0.0175 Fg/L;although some States use the drinking water MCL for this purpose. These criteria are used by stateregulatory agencies as a basis for the determination of discharge limits for arsenic depending on theclassification of the receiving water. 1 The allowable discharge is therefore affected by the ability ofthe receiving water to assimilate the arsenic without exceeding the water quality criteria.The primary cost associated with direct discharge is that of purchasing and installing thenecessary piping. Accommodations must be made for washout ports to prevent clogging because ofsedimentation in pipelines. Valving is necessary to control waste flow in the event of pipe bursts, andpipe must be laid at a sufficient depth to prevent freezing in winter months. Direct discharge requireslittle oversight, and operator experience and maintenance requirements are minimal. This method hasbeen used successfully to dispose of alum and lime sludges, as well as brine streams generated bysystems using RO and IX (DPRA, 1993a).4.3.2 Indirect DischargeIn some cases, water treatment process sludges, slurries, and brines may be discharged to aPOTW. This most often occurs when the treatment plant and POTW are under the same managementauthority. This disposal option may require the installation of a conveyance system (i.e., piping) toaccess the sanitary sewer if an adequate system is not already in place (DPRA, 1993a).Indirect discharge is a commonly-used method of disposal for filter backwash and brine wastestreams. Coagulation/filtration and LS sludges have also been successfully disposed of in this manner.However, the POTW receiving such wastes must be able to handle the increased hydraulic and solidsloading. The capacity of the sewer system must also be considered when selecting indirect dischargeas a disposal option.The residuals generated from an arsenic treatment process may be classified as an industrialwaste since they contain contaminants, namely arsenic, which may impact the quality of the sludgesgenerated by the POTW. As a result, discharge to a POTW is only acceptable when arsenicconcentrations fall within the Technically Based Local Limits (TBLL) established by the POTW under1 Note that State and local limits may be more stringent than federal limits for specific contaminants,including arsenic.4-6
the current Industrial Pretreatment Program (AWWARF, 1998). The Industrial Pretreatment Programserves to prevent NPDES violations, as well as unacceptable accumulation of contaminants in POTWsludges and biosolids. TBLLs are individually determined for each POTW, and take into accountbackground levels of contamination in municipal wastewater. Background levels are usuallymeasured in domestic wastewater. The existing TBLL would be based on the untreated drinking waterquality (higher arsenic). Removing arsenic from drinking water would change the background levelin the municipal wastewater. The TBLL would likely be revised since the background level has beenlowered. The revised TBLL would be used to determine if the brine stream from the drinking waterprocess could be discharged to the POTW. One approach to evaluating if indirect discharge is anoption is to perform a mass balance on arsenic based on the treated and untreated conditions. Thecritical factor in determining the arsenic increase at the POTW will be the volume of water lostbetween the drinking water treatment plant and the POTW. If there were no water lost between thedrinking water treatment plant and the POTW, then there would be no arsenic increase to the POTW.TBLLs for arsenic will typically be limited by the contamination of biosolids rather thaneffluent limitations or process inhibition (AWWARF, 1998). 40 CFR 503 specifies the allowablelimits for arsenic concentration in biosolids as a function of disposal method. POTWs utilizing landapplication are subject to the Land Disposal Limit, Land Application Ceiling Limit, and LandApplication Clean Sludge Limit which are 73 mg/kg, 75 mg/kg and 41 mg/kg, respectively. If thearsenic concentration of the residual exceeds the Clean Sludge Limit of 41 mg/kg, the biosolids maybe land applied, but the quantity will be limited to a total cumulative arsenic loading of 41 kg perhectare (36.6 lb/acre). As a result, most TBLLs are based on the Clean Sludge criterion (AWWARF,1998). This source appears to overstate the impact of the arsenic concentration in sludge and theability to land apply the biosolids. Biosolids with concentrations between 41 and 75 mg As/kgbiosolids can be land applied as long as the arsenic accumulation is tracked. The lifetimeaccumulation is 41 kg As/hectare of land. Using the maximum arsenic concentration of 75 mg/kgbiosolids, over 500,000 kg of biosolids would need to be applied to one hectare to exceed the limit,which is unlikely.To illustrate the impact of Part 503 regulations on the development of an arsenic TBLL,consider a limit of 41 mg/kg for the land application of biosolids (AWWARF, 1998). The typicalPOTW removal efficiency for arsenic is approximately 45 percent. Assuming biosolids productionis around 1,200 pounds per million gallons of water treated, the maximum allowable headworksloading will be around 0.109 pounds of arsenic per million gallons of wastewater treated. This4-7
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United StatesEnvironmental Protecti
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ACKNOWLEDGMENTSThis document was pr
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2.5.7 Reverse Osmosis .............
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5.0 POINT-OF-ENTRY/POINT-OF-USE TRE
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LIST OF FIGURES2-1 Pressure Driven
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LIST OF ACRONYMSAAAWWAAWWARFBLSBVC/
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POUpoint-of-useppbparts per billion
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# Alternative treatment processes s
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ends up as ferric hydroxide. In alu
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Optimization Hierarchy for Coagulat
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Substantial arsenic removal has bee
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Vickers et al. (1997) reported that
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was reduced to 0.05 mg/L when the i
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Field StudiesSurveys of lime soften
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Effect of pHpH may have significant
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RegenerationRegeneration of AA beds
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een developed provide important inf
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applicability of IX at a particular
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TABLE 2-1Typical IX Resins for Arse
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solution strength. Arsenic elutes r
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2.4.12 Typical Design ParametersThr
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2.5.2 Important Factors for Membran
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arsenic size distribution to correl
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AWWARF (1998) also performed UF pil
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presumably due to changes in electr
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RO performance is adversely affecte
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TABLE 2-10Arsenic Removal with RO a
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eversal is the decreased potential
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2.6 ALTERNATIVE TECHNOLOGIES2.6.1 I
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20 mg As per gram of iron was remov
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The most significant weakness of th
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3.0 TECHNOLOGY COSTS3.1 INTRODUCTIO
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included in the estimates presented
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Table 3-3Water Model Capital Cost B
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3.2.3 Implementing TDP Recommended
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sources. The September 1998 index v
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Amortization, or capital recovery,
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3.3 ADDITIONAL CAPITAL COSTSThe cos
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PilotingThe Technology Design Panel
Page 85 and 86: The 1993 Technology and Cost Docume
Page 87 and 88: cause disinfection by-product (DBP)
Page 89 and 90: Figure 3-1Pre-oxidation - 1.5 mg/L
Page 91 and 92: 3.6 PRECIPITATIVE PROCESSES3.6.1 Co
Page 93 and 94: enhanced coagulation treatment plan
Page 95 and 96: Figure 3-4Enhanced Coagulation/Filt
Page 97 and 98: Small Systems (Less than 1 mgd)The
Page 99 and 100: Figure 3-6Coagulation Assisted Micr
Page 101 and 102: 3.6.6 Enhanced Lime SofteningEnhanc
Page 103 and 104: Figure 3-8Enhanced Lime SofteningO&
Page 105 and 106: 3. Empty Bed Contact Time (EBCT) is
Page 107 and 108: For design flows greater than 1 mgd
Page 109 and 110: Figure 3-9Activated AluminaCapital
Page 111 and 112: Figure 3-11Activated Alumina (pH 8
Page 113 and 114: Figure 3-13Activated Alumina (pH Ad
Page 115 and 116: 3.7.2 Granular Ferric HydroxideGran
Page 117 and 118: 6. The capital costs include a redu
Page 119 and 120: Figure 3-15Bed Volumes to Arsenic B
Page 121 and 122: Figure 3-17Anion Exchange (< 20 mg/
Page 123 and 124: Figure 3-19Anion Exchange (20-50 mg
Page 125 and 126: quality feed stream and often requi
Page 127 and 128: Figure 3-20Greensand FiltrationCapi
Page 129 and 130: 3.11 COMPARISON OF COSTSThe April 1
Page 131 and 132: 4.0 RESIDUALS HANDLING AND DISPOSAL
Page 133 and 134: mechanical dewatering processes. Wh
Page 135: Storage lagoons are best suited for
Page 139 and 140: 4.3.3 Dewatered Sludge Land Applica
Page 141 and 142: usually determined by the Paint Fil
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Page 145 and 146: The solids content of the backwash
Page 147 and 148: carbonate hardness removal produces
Page 149 and 150: Domestic sewage means untreated san
Page 151 and 152: 4.4.10 Reverse OsmosisReverse osmos
Page 153 and 154: Figure 4-1Anion Exchange (< 20 mg/L
Page 155 and 156: Figure 4-3Anion Exchange (20-50 mg/
Page 161 and 162: Figure 4-9Activated Alumina (pH 7 -
Page 163 and 164: Figure 4-11Activated Alumina (pH Ad
Page 165 and 166: Figure 4-13Greensand FiltrationWast
Page 167 and 168: 5.0 POINT-OF-ENTRY/POINT-OF-USE TRE
Page 169 and 170: chromatographic peaking, which occu
Page 171 and 172: 5.3.1 Case Study 1: Fairbanks, Alas
Page 173 and 174: Manufacturer and laboratory data su
Page 175 and 176: Figure 5-2POU Reverse OsmosisO&M Co
Page 177 and 178: # Installation time - 1 hour unskil
Page 179 and 180: Figure 5-3POU Activated AluminaTota
Page 181 and 182: 6.0 REFERENCESAmy, G.L. and P. Bran
Page 183 and 184: Cooperative Research Centres for Wa
Page 185 and 186: Fuller, C.C., J.A. Davis, G.W. Zell
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Le, X.C., and M. Ma (1998). “Dete
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Scott, K., J. Green, H.D. Do and S.
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Appendix AVery Small Systems Capita
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Table A4 - VSS Document Capital Cos
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Table B1.1 - Base Costs Obtained fr
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Table B11.1 - Base Costs Obtained f
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Table B13.1 - Base Costs Obtained f
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Appendix CW/W Cost Model Capital Co
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Table C2.1 - Base Costs Obtained fr
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Table C10.1 - Base Costs Obtained f
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APPENDIX D: BASIS FOR REVISED ACTIV
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Company case study is 18 minutes (2
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egressed against their respective v
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costs for small systems is as follo
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were based on $40/sq ft). The proce
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Basis. Capital cost components incl
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The source water at Plant D has the
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equation y = (2*10 -8 )x 2 + 0.0002
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The maximum run length is 18,500 be
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Since the available arsenic capacit
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If the first column can be operated
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which includes lighting, ventilatio
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disposal costs, if needed, are cove
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Appendix EBasis for Revised Anion E
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2. The estimated cost of the anion
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9. The capital costs have been esti
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Thus, the cost of a road and fence
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length when sulfate is at or below
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the labor rates for both large and
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2. US EPA. Technologies and Costs f
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Technologies and Costs for Removal of Arsenic From Drinking Water

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