Technologies and Costs for Removal of Arsenic From Drinking Water

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length of 10,000 BV for 7 # pH < 8 may be conservative, especially for systems with lowerpH.One final factor that would increase the run length is intermittent operation at small systems.When a fixed bed process is operated intermittently, the sorbed ions can migrate deeper intothe pore structure of the media, thereby exposing more external surface area to the ions insolution. This factor also supports the use of the uncorrected run lengths in developing theO&M costs for this process.17. The two previous runs were based on operating at the natural pH without pH adjustment.Adjusting pH in larger systems is less likely to be an issue, so run lengths were alsodeveloped for operation at pH 6. Two run lengths were selected for the optimal pH of 6 -15,400 and 23,100 BV.Basis. The two run lengths for pH adjustment to pH 6 are based on pilot-scale data performedat Albuquerque (12). The Arsenic Treatment Evaluation Report (7) used the pilot-scale datato derive a run length estimate for series operation of activated alumina columns withregeneration. In the examination of this report, it was determined that there was an error inthe derivation of the run length estimate (13). A revised estimate of run length was calculatedusing the same data. The procedure described in that following modified excerpt describesthe procedure used to calculate the run length at pH 6 for disposable activated alumina.A. The equation for arsenic effluent in the Arsenic Treatment Evaluation Report (7) was used todetermine the adsorptive capacity of the lead column until arsenic breakthrough at 2 Fg/L. Theequation was based on the data from Figure 14 of the Phase 3 Report (12). It was necessaryto make one assumption to estimate the arsenic adsorbed onto the column. It was assumed thatthe influent concentration of 22.8 Fg/L was constant. From the Phase 3 Report, one columncan treat 4300 BV before arsenic breaks through at 2 Fg/L. The amount of arsenic that passedthrough the column can be determined by estimating the area under the curve defined by theD-14
equation y = (2*10 -8 )x 2 + 0.0002x + 0.8394. The integral of this equation was used to estimatethe area under the curve. The integral equation is:z = (2*10 -8 )/3*x 3 + 0.0001x 2 + 0.8394x.For x = 4300 BV:As pass = (2*10 -8 )/3*(4300) 3 + 0.0001*(4300) 2 + 0.8394*4300As pass = 5988 Fg*BV/L.The arsenic adsorbed onto the activated alumina was calculated by subtracting the arsenic thatpassed through the column from the total arsenic in the influent.As ads = As tot - As pass = (4300 BV)(22.8 Fg/L) - 5988 Fg*BV/LAs ads = 98,040 - 5988 Fg*BV/L = 92,052 Fg*BV/LThe arsenic adsorbed onto the activated alumina is often reported in milligrams arsenic pergram of activated alumina. The Phase 3 Report refers to this as As loading in Table 4. In thePhase 3 Report, a bed volume was 0.375 L. To calculate the arsenic loading, the density ofAlcoa CPN is needed. The packed bulk density for Alcoa CPN is 47 lb/ft 3 or 750 kg/m 3 .Arsenic loading is calculated as follows:As loading = [(92,052 Fg*BV/L)(0.375 L/BV)(mg/1000 Fg)](0.375 L)(dm 3 /L)(m 3 /1000 dm 3 )(750 kg/m 3 )(1000 g/kg)As loading = 0.12 mg As/g AA for breakthrough at 2 Fg/LArsenic loading will vary based on the breakthrough concentration. For breakthrough at 10Fg/L, the run length is 16,500 BV. Using the integral equation yields the following:As pass = 71,023 Fg*BV/LAs ads = (22.8 Fg/L)(16,500 BV) - 71,023 Fg*BV/L = 305,177 Fg*BV/LD-15
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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 205 and 206: Table B9.1 - Base Costs Obtained fr
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Page 214 and 215: Table C2.1 - Base Costs Obtained fr
Page 222 and 223: 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 255: 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 280 and 281: the labor rates for both large and
Page 282 and 283: 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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