Technologies and Costs for Removal of Arsenic From Drinking Water

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2.4.4 Resin TypeAs stated earlier, strong-base resins are typically used in IX arsenic removal. These resins,however, tend to prefer some ions, sulfate and chloride in particular, over arsenate. As mentionedabove, this can result in chromatographic peaking if beds are not monitored adequately. Recentstudies have also found that sulfate-selective resins tend to be superior to nitrate-selective resins forarsenic removal (Clifford, et al., 1998). Future research, however, may produce monovalentselectiveresins which will be arsenate-selective and may eliminate non-arsenic ion competition(EPA, 1994).Many resins are available for arsenic removal. Some of the commercially available resinswhich have been used in relevant IX studies are summarized in Table 2-1 (following page). Data inTable 2-1 represent BV to exhaustion using virgin IX resins. It should be noted, however, that thecapacity of the bed may decrease slightly over time. Choice of resin will ultimately be site-specific,making preliminary studies a necessity to determine optimum resin type.2.4.5 Process ConfigurationProperly configuring IX columns can improve arsenic removal and help minimize regenerationfrequency. This is because arsenic “leakage” often occurs in IX columns. In some situations, seriesoperation or implementation of certain operating methods may be needed to achieve low arseniclevels.Series operation, also known as “merry-go-round” operation, uses three beds: two inproduction and one in regeneration mode at a given time. When exchange capacity of the first bed inseries is exhausted, the first bed is removed from service to be regenerated. The second bed in seriesthen becomes the first and a freshly-regenerated bed is brought on-line to become the second. Thisallows the maximum exchange capacity of beds to be used and prevents leakage since a fresh bed isalways last in line. This also helps minimize regeneration frequency (EPA, 1995).2-22
TABLE 2-1Typical IX Resins for Arsenic RemovalResin Type Operating Parameters BV to Exhaustion ReferenceDowex 11 2 Bed Volume: 0.8 cu ftFlowrate: 1 gpmEBCT: 5.6 minDepth: 2.5 - 5 ftSulfate/As Ratio: 60:1TDS/As Ratio: 2500:1Ionac ASB-2 2 Bed Volume: 0.8 cu ftFlowrate: 1 gpmEBCT: 5.6 minDepth: 2.5 - 5 ftSulfate/As Ratio: 60:1TDS/As Ratio: 2500:1Dowex SBR-1 1 Bed Volume: 1.0 cu ftFlowrate: 1 gpmEBCT: 7.5 minDepth: 3.8 ftSulfate/As Ratio: NRTDS/As Ratio: NR4,200 Clifford and Lin(1986)4,9402,800 Hathaway andRubel (1987)Fox (1989)Ionac ASB-1- and -Dowex 111 Bed Volume: 0.014 cu ftFlowrate: NREBCT: NRDepth: NRSulfate/As Ratio: 420:1TDS/As Ratio: 9200:1C 200C 400-500[projected if As(III) isoxidized to As(V)]Clifford and Lin(1985)C A-300E(bench-scale)C A-300E(full-scale)NR = Not Reported2 Bed Volume: 0.0018 cu ftFlowrate: 0.035 gpmEBCT: NRDepth: 1.33 ftSulfate/As Ratio: 300:1TDS/As Ratio: NRC 1,340-1,640C 5,000-7,000Malcolm Pirnie(1992)Another approach for minimizing effluent levels is to operate IX columns in “counter-current flow”operation. In this mode, feed water is applied in one direction (e.g., downward) and the regenerantis applied in the opposite direction (e.g., upward). This minimizes leakage from the column.Typically columns are designed for “co-current flow” operation where the feed water and regenerantare applied in the same direction. Co-current operation increases chances for leakage, however, sinceregeneration in this mode concentrates the contaminant on the effluent end of the IX column. Using the2-23
Page 1: United StatesEnvironmental Protecti
Page 5: ACKNOWLEDGMENTSThis document was pr
Page 8 and 9: 2.5.7 Reverse Osmosis .............
Page 10 and 11: 5.0 POINT-OF-ENTRY/POINT-OF-USE TRE
Page 12 and 13: LIST OF FIGURES2-1 Pressure Driven
Page 14 and 15: LIST OF ACRONYMSAAAWWAAWWARFBLSBVC/
Page 16 and 17: POUpoint-of-useppbparts per billion
Page 18 and 19: # Alternative treatment processes s
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Page 23 and 24: ends up as ferric hydroxide. In alu
Page 25 and 26: Optimization Hierarchy for Coagulat
Page 27 and 28: Substantial arsenic removal has bee
Page 29 and 30: Vickers et al. (1997) reported that
Page 31 and 32: was reduced to 0.05 mg/L when the i
Page 33 and 34: Field StudiesSurveys of lime soften
Page 35 and 36: Effect of pHpH may have significant
Page 37 and 38: RegenerationRegeneration of AA beds
Page 39 and 40: een developed provide important inf
Page 41: applicability of IX at a particular
Page 45 and 46: solution strength. Arsenic elutes r
Page 47 and 48: 2.4.12 Typical Design ParametersThr
Page 49 and 50: 2.5.2 Important Factors for Membran
Page 51 and 52: arsenic size distribution to correl
Page 53 and 54: AWWARF (1998) also performed UF pil
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Page 57 and 58: RO performance is adversely affecte
Page 59 and 60: TABLE 2-10Arsenic Removal with RO a
Page 61 and 62: eversal is the decreased potential
Page 63 and 64: 2.6 ALTERNATIVE TECHNOLOGIES2.6.1 I
Page 65 and 66: 20 mg As per gram of iron was remov
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Page 69 and 70: 3.0 TECHNOLOGY COSTS3.1 INTRODUCTIO
Page 71 and 72: included in the estimates presented
Page 73 and 74: Table 3-3Water Model Capital Cost B
Page 75 and 76: 3.2.3 Implementing TDP Recommended
Page 77 and 78: sources. The September 1998 index v
Page 79 and 80: Amortization, or capital recovery,
Page 81 and 82: 3.3 ADDITIONAL CAPITAL COSTSThe cos
Page 83 and 84: 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
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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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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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