Technologies and Costs for Removal of Arsenic From Drinking Water

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The lower bound run length at pH 6 was based on the calculated run length for Albuquerquewater when the pH is adjusted using sulfuric acid (15,400). The upper bound run length at pH6 was based on the higher end of the range when hydrochloric acid is used instead of sulfuricacid. There are several factors that could influence run length.The first factor is that the run length for the single column is based on the data from onceregeneratedactivated alumina. It was not possible to determine the effect of regenerationbecause the influent concentration varied significantly between the two runs. Some studieshave shown some degradation after regeneration. The use of virgin media produced a longerrun length even though the influent concentration was much higher (38.8 Fg/L). Effluentconcentrations from virgin media did not exceed 2 Fg/L (.95% removal) until 7000 BV hadbeen treated using either the Alcoa CPN and the Alcan media. This is nearly double the singleunit run length of 4300 BV using the once regenerated media that serves as the basis for thetwo pH adjusted series operation options. Using the run lengths based on regenerated mediais likely to be very conservative for costing disposable activated alumina options.The second factor is that the leakage through each of the columns will be reduced. The datadescribed above for virgin media was less than 0.4 Fg/L. This may also extend the run lengthfor series operation based on virgin media because less arsenic is loaded onto the secondcolumn due to leakage.The third factor is that the data from the two full-scale facilities (3) indicated that the roughingcolumn could be operated almost complete breakthrough (effluent = influent) beforeconcentrations in the effluent of the second column exceeded 5% of the influent concentration.Complete breakthrough refers to the effluent of the first column (C 1 ) equaling the influent tothe column (C 0 ) . The finished water would be the effluent of the second column (C 2 ). Theratio of C 1 /C 0 was derived for the Alcoa CPN data in Figure 14 of the Phase 3 Report (12).C 1 .15 Fg/L at the end of the data collection (.17,000 BV)C 0 = 38.8 Fg/LC 1 /C 0 = 0.39D-20
If the first column can be operated until near complete breakthrough while maintaining arsenicconcentrations at or below 2 Fg/L, then the run lengths of 15,400 BV and 23,100 BV areprobably underestimated due to the conservative assumptions used in their derivation.18. The other major chemical cost is the pH adjustment chemicals for the two designs where pHis adjusted to the optimal pH. The following equation was used for chemical costs for pHadjustment:Chemical cost (pH adjustment) = 81361* Average Flow + 151.7Basis. The pH is adjusted downward using hydrochloric acid. The chemical demand wascalculated based on adjusting pH from pH 8 down to pH 6 with an alkalinity of 100 mg/L asCaCO 3 . The pH is adjusted back to pH 8 using sodium hydroxide. Chemical costs weredeveloped for average flows ranging from 0.05 to 1.5 mgd. The Phoenix case study presentedchemical costs of $5742 for a flow of 0.2 mgd (4). The pH was adjusted from the pH 7.5 -7.8 range down to pH 6 for those costs. The alkalinity was not listed for Phoenix. For anaverage flow of 0.15 mgd, the chemical costs were estimate to be $12,208. The chemicalcosts may be conservative for systems with lower pH and lower alkalinity. Systems withhigher alkalinity may experience higher costs. It was not possible to compare with the otherAwwaRF case studies because acid and base are used for regeneration as well as pHadjustment.19. 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 activated alumina process without regeneration is one hour per week.In addition, time is also included for media replacement (at 5% breakthrough) depending uponthe volume of media being replaced. Sixteen hours was assumed for design flows less than1 mgd and thirty-two hours for larger design flows. Incremental labor for the pH adjustmentprocesses is also included in the two options operated at optimal pH. The incremental laboris an additional two hours per week.D-21
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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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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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Technologies and Costs for Removal of Arsenic From Drinking Water

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