Technologies and Costs for Removal of Arsenic From Drinking Water

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The source water at Plant C has the following critical characteristics:ParameterArsenic (total)Average Source Water Results59 Fg/LpH 8.1Alkalinity 84 mg/L CaCO 3FluorideSulfate1.5 mg/L26 mg/LThe roughing tank treated 10,050 BV of water before breakthrough (effluent = influent). Thearsenic concentration in the effluent from the second tank was approximately 20 Fg/L. Basedon the sample results from September 2 and September 16, 1998, breakthrough above 3 Fg/L(95% removal based on average inlet of 62.1 Fg/L) in the effluent occurred somewhere withinthat time period. This converts to a run length of approximately 8500 BV. The roughing tankswere replaced with virgin activated alumina after treating 11,071 BV of water. The formerpolishing tanks then became the roughing tanks. The data indicate that the outlet arsenicconcentration was still below 4 Fg/L as the total run approached 16,000 BV. This supportsa run length of 8500 BV per replacement of half of the media. Arsenic concentration was theonly key influent parameter that varied to any extent during the testing.Run length would be affected by pH and by the influent arsenic concentration. Since influentarsenic concentrations for most systems affected by the rule should be much lower than 59Fg/L and since arsenic removal is pH dependent, a run length of 10,000 BV was selected forthe range of 7 # pH < 8. This should be very conservative for systems with lower arsenicconcentrations and pH values at the lower end of the range. The effluent pH and effluentconcentrations of alkalinity, fluoride and sulfate indicated almost no change from their valuein the influent. Thus, the existing corrosion control should be sufficient.D-12
The source water at Plant D has the following critical characteristics:ParameterArsenic (total)Average Source Water Results59.0 Fg/LpH 8.3Alkalinity 55.5 mg/L CaCO 3FluorideSulfate1.13 mg/L15 mg/LThe roughing tank treated 5,200 BV of water before breakthrough (effluent = influent). Thearsenic concentration in the effluent from the second tank was less than 2 Fg/L as it wasthroughout the run. Arsenic concentration was the only key parameter that varied to any extentduring the testing. The run length would be affected by pH and by the influent arsenicconcentration. The pH was consistent and represents the upper bound on the range ofapplicability for this cost equation. A run length of 5,200 BV was used as the run length forthe range of 8 # pH # 8.3. Since influent arsenic concentrations for most systems affected bythe rule should be much lower than 59 Fg/L, this should be a very conservative run length forsystems with lower arsenic concentrations and/or pH values at the lower end of the range.The effluent pH and effluent concentrations of alkalinity, fluoride and sulfate indicated almostno change from their value in the influent. Thus, the existing corrosion control should besufficient.The previous approach described in Appendix G of the November 1999 Technology and CostDocument (1) relied upon pilot-scale data from Severn-Trent (11). The study examinedarsenic removal over a pH range from pH 6 to pH 7.5 in a single column. The three runlengths derived from that data ranged from 16,500 BV and pH 7 to 3,000 BV at pH 8 for 10%breakthrough in a single column. Actual run lengths to 50% breakthrough in that study fornatural pH 7.5 ranged from 9,400 to 13,000 BV based on mesh size. The data from the twofull-scale facilities (3) indicated that the roughing column could be operated almost completebreakthrough (effluent = influent) before concentrations in the effluent of the second columnexceeded 5% of the influent concentration. This data also indicates that a natural pH runD-13
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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
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The 1993 Technology and Cost Docume
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cause disinfection by-product (DBP)
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Figure 3-1Pre-oxidation - 1.5 mg/L
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3.6 PRECIPITATIVE PROCESSES3.6.1 Co
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enhanced coagulation treatment plan
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Figure 3-4Enhanced Coagulation/Filt
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Small Systems (Less than 1 mgd)The
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Figure 3-6Coagulation Assisted Micr
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3.6.6 Enhanced Lime SofteningEnhanc
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Figure 3-8Enhanced Lime SofteningO&
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3. Empty Bed Contact Time (EBCT) is
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For design flows greater than 1 mgd
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Figure 3-9Activated AluminaCapital
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Figure 3-11Activated Alumina (pH 8
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Figure 3-13Activated Alumina (pH Ad
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3.7.2 Granular Ferric HydroxideGran
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6. The capital costs include a redu
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Figure 3-15Bed Volumes to Arsenic B
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Figure 3-17Anion Exchange (< 20 mg/
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Figure 3-19Anion Exchange (20-50 mg
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quality feed stream and often requi
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Figure 3-20Greensand FiltrationCapi
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3.11 COMPARISON OF COSTSThe April 1
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4.0 RESIDUALS HANDLING AND DISPOSAL
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mechanical dewatering processes. Wh
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Storage lagoons are best suited for
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the current Industrial Pretreatment
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4.3.3 Dewatered Sludge Land Applica
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usually determined by the Paint Fil
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for arsenic toxicity by a substanti
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The solids content of the backwash
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carbonate hardness removal produces
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Domestic sewage means untreated san
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4.4.10 Reverse OsmosisReverse osmos
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Figure 4-1Anion Exchange (< 20 mg/L
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Figure 4-3Anion Exchange (20-50 mg/
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Figure 4-9Activated Alumina (pH 7 -
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Figure 4-11Activated Alumina (pH Ad
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Figure 4-13Greensand FiltrationWast
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5.0 POINT-OF-ENTRY/POINT-OF-USE TRE
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chromatographic peaking, which occu
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5.3.1 Case Study 1: Fairbanks, Alas
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Manufacturer and laboratory data su
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Figure 5-2POU Reverse OsmosisO&M Co
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# Installation time - 1 hour unskil
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Figure 5-3POU Activated AluminaTota
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6.0 REFERENCESAmy, G.L. and P. Bran
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Cooperative Research Centres for Wa
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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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Page 203 and 204: Table B7.1 - Base Costs Obtained fr
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Page 243 and 244: APPENDIX D: BASIS FOR REVISED ACTIV
Page 245 and 246: Company case study is 18 minutes (2
Page 247 and 248: egressed against their respective v
Page 249 and 250: costs for small systems is as follo
Page 251 and 252: were based on $40/sq ft). The proce
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Technologies and Costs for Removal of Arsenic From Drinking Water

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