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Selecting the Optimal Coagulant to Achieve Alexandra Bowen, EIT … · 2017. 10. 17. · NEWEA –...
Transcript of Selecting the Optimal Coagulant to Achieve Alexandra Bowen, EIT … · 2017. 10. 17. · NEWEA –...
NEWEA– 2017AnnualConference&Exhibit
January25,2017
SelectingtheOptimalCoagulanttoAchieveLow-LevelPhosphorusandMetalLimits
attheUpperBlackstoneWastewaterTreatmentFacility
AlexandraBowen,EITMaureenNeville,P.E.ErikGrotton,P.E.KarlaSangrey,P.E.
NEWEA– 2017AnnualConference&Exhibit
UpperBlackstoneWastewaterTreatmentFacility
§ Serves250,000peopleincentralMassachusetts,includingtheCityofWorcester§ DischargesintotheBlackstoneRiverwhichultimatelyflowstotheNarragansettBay§ Designedfor45mgd ADFand160mgd peakhour;30mgd currentADF§ Regionalbiosolids facility
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NEWEA– 2017AnnualConference&Exhibit
§ StringentnutrientlimitsduetoBlackstoneRiver(impaired)andNarragansettBay(hypoxia)
§ Currentlyoperatingunderinterimlimits§ TNof6mg/L§ TPof0.45mg/L
§ MeetmetalslimitsbutnotTPlimit§ ChallengingcombinationofTPand
metalslimits
UpperBlackstone’sNPDESPermitLimits
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Constituent 2012Permit
Total Nitrogen(mg/L) 5.0TotalPhosphorus(mg/L)– 60-dayrollingaverage
Apr-Oct 0.10Nov-Mar 1.0
Aluminum(µg/L) 87Cadmium(µg/L)
Avg Monthly 0.2MaxDay 1.5
Copper(µg/L)Avg Monthly 7.2
MaxDay 10.2
Zinc(µg/L) 91.3LeadandNickel(µg/L) Report
NEWEA– 2017AnnualConference&Exhibit
§ NochemicaladditionortertiaryprocessforTPremoval§ RequiresadditionalprocesstoachieveTPlimit
Aerobic
Avg.SecondaryEffluent(2013-2016)TN=4.8mg/LTP=0.25mg/L
Anoxic
ReturnActivatedSludge
PreliminaryTreatmentEffluent
InternalRecycle
Anaerobic
WasteActivatedSludge
Carbon
UpperBlackstone’sAdaptiveManagementApproach
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CurrentProcessConfiguration:
ProposedProcessConfigurationforTP:
§ Requirescoagulantadditionandadd-onprocesstoachieve<0.1mg/LTP
TertiaryEffluentGoalTN<6mg/LTP<0.1mg/L
AerobicAnoxic
ReturnActivatedSludge
PreliminaryTreatmentEffluent
InternalRecycle
Anaerobic
WasteActivatedSludge
TertiarySludge
Add-onProcess
CoagulantCarbon
NEWEA– 2017AnnualConference&Exhibit
EBPRPerformance
5
0
0.2
0.4
0.6
0.8
1
1.2
1.4
0 10 20 30 40 50 60 70 80 90 100
Efflu
entTotalPho
spho
rus(mg/L)
Percentile
AprtoOct2010-2012 AprtoOct2013-2016
50thPercentile=0.54mg/L
90thpercentile =1.00mg/L
50thpercentile =0.20mg/L
90thpercentile =0.49mg/L
NEWEA– 2017AnnualConference&Exhibit
StepsTowardAchieving2012TPPermitLimit
InterimMeasures
NutrientFacilitiesPlan
Bench-ScaleTesting
Pilot-ScaleTesting
FullScaleImplementation
ofTertiaryPhosphorusRemoval
Technology
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NEWEA– 2017AnnualConference&Exhibit
BenchScaleTestingProtocol
§ Blueleaf,Inc.conductedaseriesofjartestsonsecondaryeffluent§ IfTP<0.2mg/L,spikedwithanaerobiczonemixedliquortoachieve0.2mg/LTP
§ SixcoagulantstestedatvaryingMe:TP-removed ratiosandpHlevels§ 13jartestsforeachcoagulant
§ Coagulatedsamplesfilteredthrough1.5µmfilterandanalyzedforTP§ EffluentTPobjective=0.08mg/L
§ 80%ofpermittedTPvalue
§ Responsesurfacechartscreatedusingresults§ Sulfide-basedpolymertestedat1coagulantdosewithvaryingpolymerdoses
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ResponseSurfaceTestingApproach§ Evaluatestheeffectoftwoindependentvariablesonadependentvariable,whentwo
independentvariablesinteract
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Eachofthe8perimeterpointsrepresentonejartest(aparticularcoagulantdoseandpHlevel)
Centerpointtestedwith5replicatejarstoevaluatevariability
5.86.06.26.46.66.87.07.2
0 20 40 60 80 100MolarRatio[Metal:TP]
pH
NEWEA– 2017AnnualConference&Exhibit
Aluminum-BasedCoagulants
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§ Coprecipitates/adsorbsphosphoruswithAl-hydroxideflocwithphosphates§ Surfacechemistry
§ Gelatinousflocmaynoteasilysettle(lessdensethanflocformedwithiron)
§ Unwantedaluminumintroducedtowastewater(NPDESPermit)
§ ConsideredPACl andACHsincedoesn’tsuppresspHasmuch(asalum)
§ ConsideredACHduetohigherAlcontentbyweight
Al26.98
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Alum (AluminumSulfate)Al3+≈4.4%Al
PACl (Polyaluminum Chloride)Al3+≈5.6%Al
ACH (AluminumChlorideHydrate)Al7+≈12.4%Al
NEWEA– 2017AnnualConference&Exhibit
Iron-basedCoagulants
§ Coprecipitates/adsorbsphosphoruswithFe-hydroxideflocwithphosphatesthatsettle§ Surface-chemistry
§ Iron-basedflocaremoredensethanaluminum-basedfloc,cansettlemoreeasily§ Cancausereddishbrownstainingonequipment§ Consideredferricsulfatesinceshouldhavelowercopper
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Fe55.85
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FerricChlorideFe3+≈13.5%Fe
FerricSulfateFe3+≈13.1%Fe
NEWEA– 2017AnnualConference&Exhibit
Cerium-BasedCoagulant
§ Cerium(rareearthmetal)formsacrystallinesolidprecipitatewithphosphorus§ Formsstrongionicbonds
§ Effectiveatlowermolarratios(aslowas1:1)§ Reducedchemicalusageandsludge
§ ProvenatpilotstudiesinMid-West
§ DistributedbyNeoChemicals andOxides§ FormerlynamedSorbX-100
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Ce140.1
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RE-100(CeriumChloride)Ce3+≈17.9%Ce
NEWEA– 2017AnnualConference&Exhibit
MetClearTM 2405
§ Sulfide-basedpolymerremovesheavymetals§ Anionicpolymerwithsulfidefunctionalgroups
§ Solubilityofmetalsulfideprecipitatesaremuchlessthanmetalhydroxideprecipitates§ Metalsulfideprecipitatesareamphoteric(unlikemetalhydroxideprecipitates)
§ ManufacturedbyGE§ Typicallyusedforindustrialpretreatmentapplications
§ Lowflow,highmetalsconcentrations
§ Usefultooltomitigateelevatedmetals
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Alum(AluminumSulfate)
DarkGrey:TPconcentrations>0.10mg/L(ExceedsPermit)LightBluew/dots:0.08-0.10mg/LTP
(exceedsTPobjective)LightBlue:0.05-0.08mg/LTP
(achieves TPobjective)Whitewithdots:0.04-0.05mg/LTPWhite:<0.04mg/LTP
§ AchievedTPobjectiveatallmolarratios§ 9-28mg/LasAlum
§ MosteffectiveatpH<7.0§ Canbemitigatedbyhigheralumdoses
§ MolarRatio=5:1§ Projectedannualchemicalcost:
$34,000/year
Al26.98
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PACl
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PACl(Polyaluminum Chloride)
§ AchievedTPobjectiveatmolarratios>5.5:1§ 15-46mg/LasPACl
§ HighlyDependentonpH§ IneffectiveatpH>7.7
§ MolarRatio=10:1§ Highermolarratiothanalumrequirement
§ Projectedannualchemicalcost:$336,000/year§ Muchmoreexpensivethanalum
Al26.98
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ACH(AluminumChlorideHydrate) AlAl
26.98
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§ AchievedTPobjectiveatmolarratios>15:1§ 19mg/LasACH
§ IneffectiveathighpH§ IneffectiveatpH>7.5
§ MolarRatio=15:1§ HigherthanAlumandPACl
§ Projectedannualchemicalcost:$445,000/year§ HigherthanAlumandPACl
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FerricChloride Fe55.85
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§ AchievedTPobjectiveatallmolarratiostested§ 5-15mg/LasFerricChloride
§ LittleeffectfrompH§ MolarRatio=5:1
§ SimilartoAlum
§ Projectedannualchemicalcost:$49,000/year§ SlightlyhigherthanAlumcost
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FerricSulfate Fe55.85
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§ AchievedTPobjectiveatmolarratios10:1§ 13-19mg/LasFerricSulfate
§ MoreeffectiveathigherpHvalues§ Canbemitigatedwithincreasedirondosesuptoa
point§ MolarRatio=10:1
§ HigherthanFerricChloride§ Projectedannualchemicalcost:
$159,000/year§ MuchhigherthanFerricChloridecost
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RE-100(CeriumChloride) Ce
140.1
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§ AchievedTPobjectiveatmolarratios>2:1§ 3mg/LSorbX-100
§ IneffectiveatpH>8.3§ MolarRatio=2:1
§ Thelowestmolarratioofallcoagulants
§ Projectedannualchemicalcost:$286,000/year§ GreaterthanAlumandiron-basedcoagulants,but
lessthanPACl andACH
NEWEA– 2017AnnualConference&Exhibit
CoagulationSummary
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Alum FerricChloride RE-100
Coagulantstomoveforwardtosulfide-basedpolymertesting
§ AchievedTPobjectiveatallmolarratios
§ EffectivewithoutpHadjustment
§ EstimatedMolarRatio- 5:1(9mg/L)
§ $34,000/year§ Leastexpensive
coagulant
§ AchievedTPobjectiveatallmolarratios
§ LittledependenceuponpH
§ EstimatedMolarRatio-5:1(5mg/L)
§ $49,000/year§ Secondleastexpensive
coagulant
§ AchievedTPobjectiveatmuchlowermolarratios
§ IneffectiveatpH>8.3§ ShouldnotimpactUB
operations
§ EstimatedMolarRatio- 2:1(3mg/L)
§ $286,000/year§ Highercostcouldbeoffset
bysavingsattributedtolowresiduals/solidshandling
NEWEA– 2017AnnualConference&Exhibit
ResultantMetalConcentrations
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01020304050
TypicalUBEffluent
Alum FeCl3 RE-100
Alum
inum
(µg/L)
0
0.1
0.2
0.3
0.4
TypicalUBEffluent
Alum FeCl3 RE-100
Cadm
ium(µ
g/L)
0123456
TypicalUBEffluent
Alum FeCl3 RE-100
Copp
er(µ
g/L)
§ AlumincreasesAluminum§ 17µg/Lvs.45µg/L
§ NoimpactonCadmium§ 0.32µg/Lvs.0.26µg/L
§ FeCl3 increasesCopper§ 3.8 µg/Lvs.5.0µg/L
NEWEA– 2017AnnualConference&Exhibit
MetClearTM 2405withAlumAlum dose=42mg/L
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0%
10%
20%
30%
40%
50%
60%
70%
0.25mg/L 0.50mg/L 0.75mg/L 1.00mg/L
%M
etalRed
uctio
n
PolymerDose
Al Cd Cu Pb Ni Zn
CopperReduction:52%-65%
CadmiumReduction:27%-47%
IndependentofPolymerDose
NEWEA– 2017AnnualConference&Exhibit
MetClearTM 2405withFerricChlorideFerricChloridedose=24mg/L
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0%
10%
20%
30%
40%
50%
60%
70%
0.25mg/L 0.50mg/L 0.75mg/L 1.00mg/L
%M
etalRed
uctio
n
PolymerDose
Al Cd Cu Pb Ni Zn
CopperReduction:52%-65%
CadmiumReduction:33%-46%
IndependentofPolymerDose
NickelReduction:3%-15%
NEWEA– 2017AnnualConference&Exhibit
MetClearTM 2405withRE-100RE-100 dose=16mg/L
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0%
10%
20%
30%
40%
50%
60%
70%
80%
0.25mg/L 0.50mg/L 0.75mg/L 1.00mg/L
%M
etalRed
uctio
n
PolymerDose
Al Cd Cu Pb Ni Zn
CopperReduction:56%-68%
CadmiumReduction:9%-41%
IndependentofPolymerDose
NickelReduction:9%-32%
AluminumReduction:9%-32%
CadmiumReduction:33%-46%
NEWEA– 2017AnnualConference&Exhibit
KeyConclusions
§ NopHadjustmentrequiredwithalum,ferricchloride,andSorbX§ Alumandferricchlorideweretheleastexpensivecoagulants§ RE-100achievedTPgoalsatthelowestmolarratios,butwithhighercosts§ Higherchemicalcostscouldbeoffsetbysavingsfromresidualshandling
§ MetClearTM2405wasabletoreduceheavymetalconcentrations§ Copperby>50%§ Cadmiumby30%§ Nickel(10-20%)fromFerricChlorideandRE-100samples§ Aluminum(10-30%)fromRE-100samples§ LittletonoimpactonLeadandZincConcentrations
NEWEA– 2017AnnualConference&Exhibit
StepsTowardAchieving2012TPPermitLimit
InterimMeasures
NutrientFacilitiesPlan
Bench-ScaleTesting
Pilot-ScaleTesting
FullScaleImplementation
ofTertiaryPhosphorusRemoval
Technology
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AlumFerric
Chloride RE-100
MetClear™2405
NEWEA– 2017AnnualConference&Exhibit
Acknowledgements
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GeorgeSwedberg& FredLusky
Engineering:MarkJohnson& RandyKomssiPlantOperations:MikeFoisy& JoeNowak
DanaGreen
NEWEA– 2017AnnualConference&Exhibit
Questions?Contactus!
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