Technologies and Costs for Removal of Arsenic From Drinking Water

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5.5 ION EXCHANGEIon exchange (IX) has been used effectively for the removal of arsenic. There are two typesof IX systems, anionic and cationic. IX for arsenic removal is typically anionic since arsenic presentin natural waters is generally anionic. IX is a process wherein an ion in the solid phase (e.g., asynthetic resin) is exchanged for an ion in the source water. To accomplish this exchange, the sourcewater is passed through the IX bed in either a downflow or upflow mode until the resin is exhausted.Exhaustion occurs when unacceptable levels of the contaminant are observed in the bed effluent. InPOE and POU systems water often sits in the beds for extended periods of time because the requiredflow is not constant. It is possible that this leads to better than average removal of arsenic. Furtherresearch is needed to explain this effect. The IX removal mechanism is discussed in greater detail inChapter 2.5.5.1 Cost EstimatesThe Cadmus Group (1998) document was again used as the basis for estimates of POE andPOU treatment costs. The following assumptions were made to estimate the cost of POE and POU IX:# Average household - 3 individuals, 1 gallon each per day, 1,095 gallons per year.# Annual treatment - 1,095 gallons (POU), 109,500 gallons (POE).# Minimally skilled labor - $14.50 per hour (population less than 3,300 individuals).# Skilled labor - $28.00 per hour (population greater than 3,300 individuals).# Life of unit - 5 years (POU), 10 years (POE).# Duration of cost study - 10 years (therefore, two POU devices per household).# Cost of water meter and automatic shut-off valve included.# No shipping and handling costs required.# Volume discount schedule - retail for single unit, 10 percent discount for 10 or moreunits, vendor retains 30 percent profit on more than 100 units.5-10
# Installation time - 1 hour unskilled labor (POU), 3 hours, skilled labor (POE);# O&M costs include maintenance, replacement of pre-filters and resin cartridges,laboratory sampling and analysis, and administrative costs.Due to concerns about chromatographic peaking and run lengths that typically would be lessthan 6 months, POU anion exchange is not listed as a compliance technology in the final rule (Kempic,2000). POE IX also may present problems since the brine waste from the regeneration process ischaracterized by high TDS. In addition, POE run lengths were determined to be only a few months,so frequent regeneration would be required (Kempic, 2000). Therefore, POE anion exchange is alsonot listed as a compliance technology in the final rule.5.6 ACTIVATED ALUMINAActivated alumina (AA) can be used to remove inorganic contaminants, including arsenic, fromsource water. Contaminant removal occurs as contaminants are exchanged with the hydroxide ionson the alumina surface. Since AA is an amphoteric material, its properties are closely linked to thepH of the ambient environment. At high pH (i.e., pH above 8.2), AA will act as a cationic exchanger,while at lower pHs, it will perform as an anionic exchanger. However, it is important to note that AAis rarely used at high pH (>8.3) for water treatment.Arsenic removal by AA has been shown to be most effective near pH of 5.5 to 6.0. Mostwater systems with central treatment will need some type of pH adjustment to accommodate thisrequirement. For POE and POU systems this can not be accomplished because of practical reasons.5.6.1 Cost EstimatesThe Cadmus Group (1998) document was again used as the basis to develop estimates for POEand POU treatment costs. Costs are presented in Figures 5-3 for total capital costs and 5-4 for annualO&M costs. The cost curves are based on the following assumptions:# Average household - 3 individuals, 1 gallon each per day, 1,095 gallons per year.# Annual treatment - 1,095 gallons (POU), 109,500 gallons (POE).5-11
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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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This page was intentionally left bl
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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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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 and 136: Storage lagoons are best suited for
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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
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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 157 and 158: Figure 4-5Coagulation Assisted Micr
Page 159 and 160: Figure 4-7Coagulation Assisted Micr
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: Figure 5-2POU Reverse OsmosisO&M Co
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
Page 187 and 188: Le, X.C., and M. Ma (1998). “Dete
Page 189 and 190: Scott, K., J. Green, H.D. Do and S.
Page 191: Appendix AVery Small Systems Capita
Page 194 and 195: Table A4 - VSS Document Capital Cos
Page 197 and 198: Table B1.1 - Base Costs Obtained fr
Page 207 and 208: Table B11.1 - Base Costs Obtained f
Page 209 and 210: Table B13.1 - Base Costs Obtained f
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Table C14.1 - 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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