Technologies and Costs for Removal of Arsenic From Drinking Water

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length when sulfate is at or below 20 mg/L is 1500 bed volumes (BV). The run length whensulfate is between 20 and 50 mg/L sulfate is 700 BV.Basis. The November 1999 Technology and Cost Document (2) utilized a breakthrough curvefrom a computer program based on equilibrium multicomponent chromatography theory withconstant separation factors (11). The number of bed volumes for 10 percent and 50 percentbreakthrough of influent arsenic were presented as a function of influent sulfate concentration.The 10 percent breakthrough curve would correspond to 90% removal of arsenic. Thisbreakthrough curve was presented in Figure 3-37 of the November 1999 Technology and CostDocument (2). Run length for the entire range was based on the run length at the highest sulfateconcentration. A run length of 1500 BV for sulfate concentrations up to 20 mg/L is based onthe run length at 20 mg/L. A run length of 700 BV for sulfate concentrations in the range of 20to 50 mg/L is based on the run length at 50 mg/L. This is a very conservative assumption. Forexample, a system with 25 mg/L would have a run length of 1300 BV, but is assumed to havea run length of 700 BV. The actual run length would be nearly double the run length being usedto estimate costs. One other source of conservatism in these estimates. The breakthroughcurve presented in the November 1999 Technology and Cost Document may underestimateactual run length. The run length observed in pilot testing at Albuquerque was 506 BV whenregeneration was performed with 2.0 equivalent chloride per equivalent resin and downflowregeneration with 1 molar (M) salt solution (12). The sulfate level was 81.7 mg/L. Thepredicted run length would be approximately 420 BV using the graph in the November 1999Technology and Cost Document (2).The regeneration frequency can be calculated using the run length (number BV), the size of aBV (gallons), and the average daily flow. The regeneration frequency is reported in days.This can also be reported as number of regenerations per week.14. The regeneration dose is also a critical element for the O&M costs. The salt dose forregeneration was 10.2 lb/ft 3 .Basis. Regeneration in the Albuquerque study (12) was achieved using a 1 M sodium chloridesolution at a regeneration level of 2 eq chloride/eq resin (10.2 lbs NaCl/ft 3 resin).E-8
15. The second major component in the O&M costs is incremental labor cost. Incremental laboris the labor associated with the additional maintenance that comes with a new process.Adjustment in staffing or shifting of activities are not included in the incremental labor. Theincremental labor for the anion exchange is one hour per week plus three hours perregeneration.Basis. The Very Small Systems Document states that fours per day are required for resinregeneration, routine equipment maintenance and process oversight (10). This section coversboth cation and anion exchange, so this estimate is likely based on daily or more frequentregeneration for cation exchange softening or nitrate removal. The Water Model (3) lists laborhours per year based on the frequency of regeneration. The number of hours varies based onresin volume. For daily regeneration, the range is between 200 and 300 hours per year - lessthan one hour per day. One hour per week for routine equipment maintenance and three hoursper regeneration was assumed based on both sources.16. The labor rate for small systems was $28/hour. The loaded labor rate for large systems was$52/hour.Basis. A rate of $28/hour is recommended as a loaded labor rate for small systems at the EPATechnology Design Workshop Summary included in Annex A of the Phase I UpgradeDocument (8). A loaded labor rate of $52/hour was selected for large systems based onlicensed operators. For this analysis, a large system was defined as a system with an averageflow greater than 0.36 mgd (corresponds to a design flow of 1 mgd). This corresponds topopulations lower than 3,300 people. The use of a large system rate may overestimate costsin systems serving between 2,700 and 10,000 people.The Design Workshop Summary (8) also noted that the Bureau of Labor Statistics (BLS)publishes monthly reports that include fully burdened labor costs on a regional basis. Othermembers of the Panel noted that some States have conducted operator surveys that includelabor rates. The Panel recommended that EPA review and compare both the BLS and Statematerial to derive representative rates. A preliminary analysis of such material indicates thatE-9
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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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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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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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Page 280 and 281: the labor rates for both large and
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Technologies and Costs for Removal of Arsenic From Drinking Water

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