Technologies and Costs for Removal of Arsenic From Drinking Water

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Basis. The labor requirements when operated at natural pH are minimal. The chemicalfeeders have been eliminated since the media is replaced rather than regenerated and theprocess is operated at the raw water pH. If backwashing every four months is necessary, thenit could be done in the allotted time. Estimated total annual labor costs were provided for theBow, NH system (2). These estimates were based on four hours per month for routineinspections and 16 hours/cycle for filter media replacement. The hours for activated aluminamedia replacement were doubled for the design flows greater than 1 mgd because of the largervolume of media to be replaced. When operated at the optimal pH, an additional two hoursper week is used for the pH adjustment processes. Technical oversight is reduced due to theuse of pH controllers, pH sensors, and level sensors in this design.]20. 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 thatthe labor rates for both large and small systems may be very conservative and that actual laborrates may be much lower.]21. The third component in the O&M costs is the energy costs for both the building and theprocess. Housing electrical energy use is based upon an annual usage of 19.5 kwh/sq ft/yr,D-22
which includes lighting, ventilation, and heating. Process electrical energy was assumed tobe 440 kwh/yr. Costs were based on a rate of $0.08/kwh.Basis. The Water Model was used for the electrical usage estimates. The housing electricaluse is taken directly from the O&M cost discussion on activated alumina. Lighting is requiredonly when the operator is present, which was assumed to be average 3 hours per day. Lightingwould likely be needed less frequently under the simplified design. The process electricalenergy requirements were also taken from the Water Model. However, they were modifiedsignificantly since regeneration is not being performed in this design. Process electricalenergy is required for day tank mixers and diaphragm pumps to feed from the day tanks.Mixers were assumed to operate one-half hour per day, with the diaphragm feed pumpsoperating 24 hours per day. The other major energy use component was the electricalimmersion heater used to maintain the sodium hydroxide tanks above freezing (14.4 EC) andit was assumed to operate 4 hours per day and 180 days per year. Since all of these majorenergy use components are not included in the design, the process energy requirements inTable 67 of the Water Model were examined for the smallest design flow (0.045 mgd). Theprocess energy requirements were assumed to be one-tenth of the listed energy requirementsand assumed to be constant over the entire flow range. Power costs were consistently higherusing this approach compared with the Phoenix data (4).D.3 WASTE DISPOSAL COSTS22. The primary waste is the spent activated alumina. Rates for disposal at sanitary landfills arebased on tons of material. A wet density is assumed to be 10% higher than the dry density toconvert the volume of activated alumina into a mass for disposal.Basis. The cost estimate for the White Rock Water Company was based on the mass of themedia and did not assume a higher wet density (2). The Phoenix case study was the only onethat investigated disposable activated alumina. The disposal costs are based on a 10%increase in the mass of the media (4). The wet density of the media was assumed to be 10%higher than the dry density.D-23
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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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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
Page 253 and 254: Basis. Capital cost components incl
Page 255 and 256: The source water at Plant D has the
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Page 261 and 262: Since the available arsenic capacit
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Page 272 and 273: 2. The estimated cost of the anion
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Page 276 and 277: Thus, the cost of a road and fence
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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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