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.


UpperBlackstoneWastewaterTreatmentFacility

§ Serves250,000peopleincentralMassachusetts,includingtheCityofWorcester§ DischargesintotheBlackstoneRiverwhichultimatelyflowstotheNarragansettBay§ Designedfor45mgd ADFand160mgd peakhour;30mgd currentADF§ Regionalbiosolids facility

2


§ StringentnutrientlimitsduetoBlackstoneRiver(impaired)andNarragansettBay(hypoxia)

§ Currentlyoperatingunderinterimlimits§ TNof6mg/L§ TPof0.45mg/L

§ MeetmetalslimitsbutnotTPlimit§ ChallengingcombinationofTPand

metalslimits

UpperBlackstone’sNPDESPermitLimits

3

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


§ NochemicaladditionortertiaryprocessforTPremoval§ RequiresadditionalprocesstoachieveTPlimit

Aerobic

Avg.SecondaryEffluent(2013-2016)TN=4.8mg/LTP=0.25mg/L

Anoxic

ReturnActivatedSludge

PreliminaryTreatmentEffluent

InternalRecycle

Anaerobic

WasteActivatedSludge

Carbon

UpperBlackstone’sAdaptiveManagementApproach

4

CurrentProcessConfiguration:

ProposedProcessConfigurationforTP:

§ Requirescoagulantadditionandadd-onprocesstoachieve<0.1mg/LTP

TertiaryEffluentGoalTN<6mg/LTP<0.1mg/L

AerobicAnoxic

ReturnActivatedSludge

PreliminaryTreatmentEffluent

InternalRecycle

Anaerobic

WasteActivatedSludge

TertiarySludge

Add-onProcess

CoagulantCarbon


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




StepsTowardAchieving2012TPPermitLimit

InterimMeasures

NutrientFacilitiesPlan

Bench-ScaleTesting

Pilot-ScaleTesting

FullScaleImplementation

ofTertiaryPhosphorusRemoval

Technology

6


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

7


ResponseSurfaceTestingApproach§ Evaluatestheeffectoftwoindependentvariablesonadependentvariable,whentwo

independentvariablesinteract

8

Eachofthe8perimeterpointsrepresentonejartest(aparticularcoagulantdoseandpHlevel)

Centerpointtestedwith5replicatejarstoevaluatevariability

5.86.06.26.46.66.87.07.2

0 20 40 60 80 100MolarRatio[Metal:TP]

pH

Chemicals


Aluminum-BasedCoagulants

10

§ Coprecipitates/adsorbsphosphoruswithAl-hydroxideflocwithphosphates§ Surfacechemistry

§ Gelatinousflocmaynoteasilysettle(lessdensethanflocformedwithiron)

§ Unwantedaluminumintroducedtowastewater(NPDESPermit)

§ ConsideredPACl andACHsincedoesn’tsuppresspHasmuch(asalum)

§ ConsideredACHduetohigherAlcontentbyweight

Al26.98

13

Alum (AluminumSulfate)Al3+≈4.4%Al

PACl (Polyaluminum Chloride)Al3+≈5.6%Al

ACH (AluminumChlorideHydrate)Al7+≈12.4%Al


Iron-basedCoagulants

§ Coprecipitates/adsorbsphosphoruswithFe-hydroxideflocwithphosphatesthatsettle§ Surface-chemistry

§ Iron-basedflocaremoredensethanaluminum-basedfloc,cansettlemoreeasily§ Cancausereddishbrownstainingonequipment§ Consideredferricsulfatesinceshouldhavelowercopper

11

Fe55.85

26

FerricChlorideFe3+≈13.5%Fe

FerricSulfateFe3+≈13.1%Fe


Cerium-BasedCoagulant

§ Cerium(rareearthmetal)formsacrystallinesolidprecipitatewithphosphorus§ Formsstrongionicbonds

§ Effectiveatlowermolarratios(aslowas1:1)§ Reducedchemicalusageandsludge

§ ProvenatpilotstudiesinMid-West

§ DistributedbyNeoChemicals andOxides§ FormerlynamedSorbX-100

12

Ce140.1

58

RE-100(CeriumChloride)Ce3+≈17.9%Ce


MetClearTM 2405

§ Sulfide-basedpolymerremovesheavymetals§ Anionicpolymerwithsulfidefunctionalgroups

§ Solubilityofmetalsulfideprecipitatesaremuchlessthanmetalhydroxideprecipitates§ Metalsulfideprecipitatesareamphoteric(unlikemetalhydroxideprecipitates)

§ ManufacturedbyGE§ Typicallyusedforindustrialpretreatmentapplications

§ Lowflow,highmetalsconcentrations

§ Usefultooltomitigateelevatedmetals

13

Results

NEWEA– 2017AnnualConference&Exhibit15

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

13


PACl

16

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

13


ACH(AluminumChlorideHydrate) AlAl

26.98

13

§ AchievedTPobjectiveatmolarratios>15:1§ 19mg/LasACH

§ IneffectiveathighpH§ IneffectiveatpH>7.5

§ MolarRatio=15:1§ HigherthanAlumandPACl

§ Projectedannualchemicalcost:$445,000/year§ HigherthanAlumandPACl


FerricChloride Fe55.85

26

§ AchievedTPobjectiveatallmolarratiostested§ 5-15mg/LasFerricChloride

§ LittleeffectfrompH§ MolarRatio=5:1

§ SimilartoAlum

§ Projectedannualchemicalcost:$49,000/year§ SlightlyhigherthanAlumcost


FerricSulfate Fe55.85

26

§ AchievedTPobjectiveatmolarratios10:1§ 13-19mg/LasFerricSulfate

§ MoreeffectiveathigherpHvalues§ Canbemitigatedwithincreasedirondosesuptoa

point§ MolarRatio=10:1

§ HigherthanFerricChloride§ Projectedannualchemicalcost:

$159,000/year§ MuchhigherthanFerricChloridecost


RE-100(CeriumChloride) Ce

140.1

58

§ AchievedTPobjectiveatmolarratios>2:1§ 3mg/LSorbX-100

§ IneffectiveatpH>8.3§ MolarRatio=2:1

§ Thelowestmolarratioofallcoagulants

§ Projectedannualchemicalcost:$286,000/year§ GreaterthanAlumandiron-basedcoagulants,but

lessthanPACl andACH


CoagulationSummary

21

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


ResultantMetalConcentrations

22

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


MetClearTM 2405withAlumAlum dose=42mg/L

23

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


MetClearTM 2405withFerricChlorideFerricChloridedose=24mg/L

24

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




NickelReduction:3%-15%


MetClearTM 2405withRE-100RE-100 dose=16mg/L

25

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




NickelReduction:9%-32%

AluminumReduction:9%-32%



KeyConclusions

§ NopHadjustmentrequiredwithalum,ferricchloride,andSorbX§ Alumandferricchlorideweretheleastexpensivecoagulants§ RE-100achievedTPgoalsatthelowestmolarratios,butwithhighercosts§ Higherchemicalcostscouldbeoffsetbysavingsfromresidualshandling

§ MetClearTM2405wasabletoreduceheavymetalconcentrations§ Copperby>50%§ Cadmiumby30%§ Nickel(10-20%)fromFerricChlorideandRE-100samples§ Aluminum(10-30%)fromRE-100samples§ LittletonoimpactonLeadandZincConcentrations


StepsTowardAchieving2012TPPermitLimit

InterimMeasures

NutrientFacilitiesPlan

Bench-ScaleTesting

Pilot-ScaleTesting

FullScaleImplementation

ofTertiaryPhosphorusRemoval

Technology

27

AlumFerric

Chloride RE-100

MetClear™2405


Acknowledgements

28

GeorgeSwedberg& FredLusky

Engineering:MarkJohnson& RandyKomssiPlantOperations:MikeFoisy& JoeNowak

DanaGreen


Questions?Contactus!

29

Findmoreinsightsthroughourwaterpartnershipatcdmsmith.com/waterand@CDMSmith

InsertCRPCDlogohere?

Questions?Contactus!

[email protected]

[email protected]

selecting the optimal coagulant to achieve alexandra bowen, eit … · 2017. 10. 17. · newea –...

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