Engineering Considerations for Phosphorous Removal

7/28/2019 Engineering Considerations for Phosphorous Removal

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ENGINEERINGCONSIDERATIONS

FOR

PHOSPHOROUSREMOVAL


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y ChemicalPhosphorusRemoval(ChemP)vs.Biological

PhosphorusRemoval(BioP)

y FactorsAffectingSelection

y

P

limits

in

NPDES

Permity DependentonPermitlimit/degreeofremovalneeded

y Typeofcurrenttreatmentprocesses

y

Extent

of

plant

modifications

needed

cost

and

operationy Capacityofsludgehandlingsystem

y Futurerequirements

y

Influent

wastewater

characteristics

Overview


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ChemicalPhosphorusRemoval

y FormPrecipitatesUsingMetal

Salts

y CommonMetalSalts

y Alumy FerrousChloride(byproduct)

y FerricChloride

y Notsocommon

y Ferrous/FerricSulfate

y

Lime


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y ApplicationPoints

y

Provide

multiple

locations

for

flexibilityy Preprecipitation

y Rawsewagepriortoprimarysedimentation

y Coprecipitation

y Primarysedimentationeffluent

y Mixedliquorintheactivatedsludgeprocess

y

Biological

process

unit

effluenty Postprecipitation

y Secondaryclarifiereffluent

y

Only

with

tertiary

treatment/filtration

ChemicalPhosphorus

Removal


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ChemicalPhosphorus

Removal

y Whatisneededtomodifyanexistingfacility?

y Notalot?y Chemicalstoragetanky Feedpumps

y Pipingy Applicationpointsy Mixing??(dependsonlocation)

y

Evaluate

sludge

handling

capacityy Digestersy Dewateringy Storage

y Pumping


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ChemicalPhosphorus

Removal

y Considerationsforchemicalstorageandfeedsystems

y Storagetank

y Multipletanks

y Volume

y Lengthofstoragetime

y Deliveryvolume

y Location(indoors/outdoors)

y Secondarycontainment

y Typeof

pumps/controls

y Flowpaced?

y Undergroundcasing

pipe/handholes


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y UsingChemP:

y Constantlyadjustthechem feedpumpstomatchflow

y Canoverfeed

chemical

y Erroronthesideofcaution

y Allowfordiurnalflowvariations

y Flowpacing

(?)

consider

recycle

stream

slug

load

conc.

y SeasonalAdjustments

y Winter

y Addmorechemicaltomaintaincompliance

y HighereffluentPvalues

y Cantlandapply

ChemicalPhosphorus

Removal


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ChemPRemoval

Side

Effects

y MetalsaltswithUVsystemsy Ferric/ferrous coatslamps,frequent

cleaningy Alum OK

y Impacts/effectsofreturnstreamsy HigherPininfluent

y Slugloads

y Impactonsludgeproductionandcharacteristicsy Significantincreasey Land

app

impacts/limits

y O&Mcostimpactsy Chemicalcostsy Sludgedisposalcosts


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ChemPSummary

y Advantages

y Easytoimplement

y Simpleoperation

y Disadvantages

y

Increased

sludge

production

y AddedO&Mexpense

y Chemicalcosts

y Sludgehandlingcosts

y Ferric/ferroussaltscorrosion


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y Fairlynewtechnology

y

Growmicroorganisms

that

take

up

extra

P(PAOs)

y Produceproperenvironment

y Requiressignificantmodificationstoexistingfacility

y Relativelyhigh

capital

costs

y LoweroperatingcostcomparedtoChemP

y Avoidorminimizechemicaladdition

y Producesminimal

additional

sludge

BiologicalPRemoval


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y Whatsinvolved?

y Anaerobic/aerobiccyclingofmixedliquor

y Requiresvolatilefattyacids(VFA)

y Growselect

organisms

in

MLSS

to

take

up

and

storeP

y

Remove

organism

(&

P)

in

waste

sludgey Removalofsolidsfromeffluent

BiologicalPRemoval


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BioPOxidation

Ditch

&

Anaerobic

Selector

Tank


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y AerationInfluentcharacteristics/loadings

y MostBio

Pplants

designed

w/o

primary

clarifiers

y Challengesofprimaryeffluent

y Need>~20:1CBOD5:P,~40:1BOD5:COD

y i.e.,too

little

CBOD5 can

hinder

Bio

P

y PrefermentationforVFAs

y Affectssizeofanaerobiczone

y If


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BiologicalPRemoval

y Whatisneededtomodifyexistingfacility?y

Activatedsludge

systems:

y Anaerobicselectortanky Ifnitrifying,consideranoxic

zonealso

y Removenitrates

(oxygen

source)y Automation/controly Evaluatesludgehandling

capacityy Digestersy Dewateringy Storage

y Tertiarytreatment???


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y BioPOperationalControl

y KeepMLSS

at

consistent

concentration

(waste

regularly)

y Minimalsludgeblanketinfinalclarifiers(avoidPrelease)

y RASflowpaced

y SRT typically

5to

15

days

y CanloseBioPatlowtemps(


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y Impacts/effectsofreturnstreamonotherprocesses

y Slugloads of

P

y Considersidestream treatmentorstorage

y Impactonsludgeproductionandcharacteristics

y BythenatureofBNR,phosphorousaccumulatesinthebiosolids

y HighPinWAStoanaerobicdigesters struvite

y Lessdry

tons

produced

than

with

Chem

P

y Landappimpacts/limits

y O&Mcostimpacts

BiologicalPRemoval


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BioPSummary

y Advantages

y

Reduce/eliminate

chemical

addition

y Reduce/eliminatealkalinityadditionduetoChemP

y Selectsfor

flocculating

bacteriavs.Filamentousbacteria=bettersettling

y Reducesaeration

requirements

y Canimprovenitrification

rates

in

aerobic

zone

y Disadvantages

y

Higher

capital

costs

than

ChemP

y Requiresmorecarefuldesign

y Moresensitiveoperation

y LimitationonnitrateandD.O.recycletoanaerobiczone

y PreventPrelease

in

clarifiers


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y Customaryprocessesforleveloftreatment(mg/LTP)

BioP ChemP

y Secondary 1.0 0.5

Effluent

y Filtered 0.3.05 0.10.2

Effluent

TreatmentProcess

for

PLimits


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TertiaryTreatmentOptions

y Filtration

y Gravitysandfilters

y Pressurefilters

y Diskfilters

y PolishingPonds

y TertiaryClarifier


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TertiaryTreatmentOptions


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y Clarifiersizingforphosphorusremoval

y Per10StatesStandards

Additional

Topics

Treatment Process

Surface Overflow Rate

at Design Peak Hourly Flow*

Peak Solids Loading Rate***

gpd/ft2 lb/day/ft2

Conventional, Step Aeration,

Complete Mix, Contact Stabilization,

Carb. Stage of Separate Stage Nitr.

1,200** 50

Extended Aeration

Single Stage Nitrification1,000 35

2 Stage Nitrification 800 35

Activated Sludge with Chemical addition toMixed Liquor for Phosphorus Removal

900**** AsAbove

* Basedoninfluentflowonly

** Plantsneedingtomeet20mg/Lsuspendedsolidsshouldreducesurfaceoverflowrateto1,000gallonsperday persquarefoot

*** Clarifierpeaksolidsloadingrateshallbecomputedbasedonthedesignmaximumdayflowthedesignmaximumreturnsludge

rate

requirement

and

the

design

MLSS

under

aeration

**** Whenphosphorusremovaltoaconcentrationoflessthan 1.0mg/L isrequired


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y Clarifiersizingforphosphorusremoval

y

Modifications/optimizingexisting

clarifiers

y PLimit


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Stamfordbaffles


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Aquatic&NaturalSystems

y ExistingPonds&Lagoons

y SupplementalProcesses

y Clarifierswithchem feed

y Sludgehandling

required

y Consideralongwith

ammoniaremoval

(futurelimits?)


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NutrientFarmingProcessesforSidestreams

y Nutrientrecoveryprocesses

y Producesstruvite fertilizery ReducesrecyclingofP&Ny Reducesstruvite formation

y Ostara

y Multiform

Harvest


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1. Whichof

the

following

chemicals

is

NOT used

for

chemicalprecipitationinwastewatertreatment:a) Alum

b) Ferric

Chloridec) FerrousChloride/hydrochloricacidmixture(pickleliquor)

d) FerricSulfate

e) Lime

f) None allcanbeused

Test

Time!!!!MultipleChoice


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2. InaWWTPwithprimarytreatmentandsecondarytreatment,whichONEofthefollowinggenerallocationswouldaddingametalsalttoremove

phosphorus

NOT

be

beneficial:a) Preprecipitation addedtorawsewagepriortoprimary sedimentation

b) Coprecipitation addedtoprimarysedimentationeffluent

c) Coprecipitation addedtomixedliquorintheactivatedsludgeprocess

d) Coprecipitation

added

to

the

biological

process

unit

effluent

e) Postprecipitation addedtothesecondaryclarifiereffluent

f) None allabovelocationswouldbebeneficial

3. Alumis

an

abbreviated

term

for

what

chemical?

Fullname: Chemicalformula: _________

Aluminumsulfate Al2(SO4)3

TestTime

(cont.)


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4. Howmanypoundsofachemical,appliedattherateof5mg/L,arerequired

to

dose

7 million

gallons?a. 35.0lb

b. 58.4lb

c. 291.9lb

d.

350.0lb

5. A15,000galtankisfullofaliquidchemicalwithaspecificgravityof1.25.Whatistheweightofthecontentsofthetank?

a. 7819lb

b. 18,750lb

c. 125,100lb

d. 156,375lb

TestTime

(cont.)

5mg/Lx7MGDx8.34=291.9

8.34lb/galx1.25S.G.x15,000gal=156,375lb


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6. WhichofthefollowingisNOT atypicalconsideration

whenevaluating

which

chemical

to

utilize

for

phosphorusremoval?

a. Costofthechemical

b.Alkalinity

consumption

c. Quantitiesofsludgegeneratedbyitsaddition

d. Ultravioletlighttransmittance

e.

Safetyand

handling

requirements

f. Oxygentransferrate

TestTime

(cont.)


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7. Circlethetwo (2)generaltypesofcolloidalsolidparticle

dispersionsin

liquids.

a. Heterotropic

b. Hydrophobic

c.

Hemophilic

d. Hydroliphic

e. Hydroponic

f.

Hydrophilic

g. Hydrostatic

h. Hydrofluxcapacitor

TestTime

(cont.)


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8. Additionofalumwillincreasethealkalinityinthewaterbeingtreatedduringthecoagulationprocess.

9. Theformation

of

limestone

(calcium

carbonate)

is

notaseriousprobleminlimesystemsusedforphosphorusremoval.

10. Addingametalsalttoaprimarysedimentation

basinwill

not

affect

BOD

and

TSS

removal

efficiencies.

11. Addingferrousmetalsaltscanaffectthealkalinityofyourwastewaterstream.

12. Intheluxuryuptakephosphorusremovalprocess,bacteriareleasephosphorusinanaerobicreleasetank.

Test

Time

True/FalseFALSE

FALSE

FALSE

TRUE

FALSE


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13. Inmostcases,ferroussulfatecannotbeusedaloneasaprecipitantbecauselimemustbeaddedatthesametimetoformaprecipitate.

14. If yourNPDESPermitdoesnotincludephosphorusortotalnitrogenlimits,youcannotusechemicalprecipitationtoimproveplantperformance.

15. Polymerscanbeusedinconjunctionwithmetalsaltstoaidinphosphorusremoval.

16. Priortoanactivatedsludgetypeoftreatmentprocess,

it

is

desirable

to

remove

as

much

phosphorusaspossibleintheprimaryclarifiers.

17. Everyoperatorhasaresponsibilitytoensurethatthe

treatments

plants

are

a

safe

place

to

work

and

visit.

Test

Time

(cont.)TRUE

FALSE

TRUE

FALSE

TRUE


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Questions?

Engineering Considerations for Phosphorous Removal

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