磷回收技术专业知识讲座

PPhosphorusRecoveryTechniquesCONTENTSPARTONE

IntroductionPARTTWO

Reserves

SituationPARTTHREE

Techs

for

P-RecoveryPARTFOUR

Discussion1PARTONEINTRODUCTIONINTRODUCTIONWhat

is

Phosphorus？Phosphorusisanonmetalofthenitrogengroupandisessentialforalllifeonourplanet.Phosphaterock/phosphoriteandaregeologicaldepositsofphosphateexistingallovertheworld:sedimentaryandigneousphosphaterockdeposits.Themajorityoftoday’sglobalphosphaterockproductionisusedinagriculturalproductsand/orapplications,mainlyinfertilizers(CisseandMrabet,2023).Cisse,L.,andMrabet,T.(2023).Worldphosphateproduction:overviewandprospects.PhosphorusResearchBulletin,15,21–25.INTRODUCTIONDepletion

of

PhosphorusHowever,

naturalPresources(phosphaterock)aredepleting.And

theregulationsonthedischargeofphosphorushasbeenincreasinglystringent

(Steen,1998).The

potentialtechniquestorecoverphosphorus

fromwastestreamsinviewofenhancingtheavailability

needs

to

be

explored.Existingfull-scaleP-recoverytechniquescan

be

divided

due

to

its

field

among

theliquidphase,

sludge

phase,andsludge

ash.Althoughthefull-scale

P-recoverytechniqueshavebeenshowntobetechnologicallyfeasible,

theeconomicalfeasibility,legislationandnational

policiesarethemajorreasonswhythesetechniquesarenotyetoperational

worldwide.Steen,I.(1998).Phosphorusavailabilityin21stcentury:managementofanonrenewable

resource.PhosphorusandPotassium,217,25–31.2PARTTWORERESERVES

SITUATIONRERESERVES

SITUATIONAgricultural

ApplicationsNon-Agricultural

ApplicationsThe

Utilization

of

PhosphorusFertilizer

industryPesticidesAnimal

fees

supplementsFood

industryHousehold

applicationsMetal

surface

treatmentCorrosion

inhibitionFlame

retardantsMuller,J.,Reinhardt,M.,G¬unther,L.,Dockhorn,T.,Dichtl,N.,Urban,I.,Weichgrebe,D.,Rosenwinkel,K.H.,Bayerle,N.,andVesterager,N.O.(2023).Fundamentalsandfeasibilityofnutrientrecyclingusingtheseaborneprocess.ConferenceontheManagementofResiduesEmanatingfromWaterandWastewaterTreatment,Johannesburg,South-Africa.RERESERVES

SITUATIONMoroccoMost

important

ProducerLow-level

consumptionAsia

(China)High-level

productionExceeding

consumptionFigure1.GlobalproductionandConsumptionofphosphorus(datafromU.S.Geologicalsurvey,2023;IFA,2023).North

AmericaConsiderable

reserves

Large

productionLack

of

high-quality

p-rockCurrent

DistributionRERESERVES

SITUATIONOpen/Close

P-cycleOpen

Phosphorus

CycleBothsolidandliquidsourcesareregardedaswastestreams.Thefocusliesonminimizingthecostofdisposal.Thewasteenterstheenvironment,causingphosphoruslossesandeutrophicationproblems.11%removedinprimarytreatment(primarysludge)20-30%removedinsecondarytreatment(activated/surplussludge)Approximately90%removedandincorporatedintothesewagesludge(CornelandSchaum,2023)Thesludgeproducedendedupinlandfills,incineratorsorinthesedimentsofcanalsandrivers(Mainstoneetal.,2023).Cornel,P.,andSchaum,C.(2023).Phosphorusrecoveryfromwastewater:needs,techniquesandcosts.WaterScienceandTechnology,59,1069–1076.Mainstone,C.P.,Davis,R.D.,House,A.,andDay,M.(2023).Phosphorusandriverecology:tacklingsewageinputs.EnglishNature,Peterborough,England.RERESERVES

SITUATIONOpen/Close

P-cycleClose

Phosphorus

Cycle/Sludge

AshP-Recovery

liquid

phaseP-Recovery

solid

phasePhosphatecanberecoveredfromtheliquidphase,sludgephaseandmono-incinerated(sludgeisincineratedseparatelyfromotherwastes)sludgeash(CornelandSchaum,2023).Thephosphorusrecoveryratefromtheliquidphasecanreach40–50%atmost,whilerecoveryratesfromsewagesludgeandsewagesludgeashcanreachupto90%(CornelandSchaum,2023).ThesubstantialdifferencebetweenthetraditionalPremovalandP-recoveryfromwastewateristhatPremovalaimsatobtainingaPfreeeffluentbytransferringPtosludgewithchemicalandbiologicalprocesses.P-recovery,ontheotherhand,aimsataP-containingproductthatcanbereusedeitherinagricultureorinP-industry.Cornel,P.,andSchaum,C.(2023).Phosphorusrecoveryfromwastewater:needs,techniquesandcosts.WaterScienceandTechnology,59,1069–1076.3PARTTHREETECHS

FOR

P-RECOVERYTECHS

FOR

P-RECOVERYFinal

Products1Lessindependentofp-concentration,butmorerelatedtowastewateralkalinity.TheincreaseofboththesolutionpHvalueandtheCa/Pratioaretwoapproachestooverenegativeinfluenceofcarbonateontheprecipitationofphosphate.Becauserecoveredcalciumphosphateistheeffectivepositionofphosphaterock,itcanbereadilyacceptedbythephosphateindustry(Driveretal.,1999).Calcium

Phosphate2Magnesiumisthelimitingelement

inmostsewagetreatmentapplicationsMgCl2orMgO

isaddedtotheprocessas.Thesaturation

pointofasolutionisstronglyinfluencedbypH,Ifthefeedstream

doesnothavesufficientalkalinity,sodiumhydroxideisaddedand/orCO2

isstrippedfromthesolution.Strutive3Itcanbefurtherprocessedtohighqualityphosphoricacidandotherphosphoruspounds.Phosphoricacidobtainedviawhitephosphorusisthemainsourceofphosphatesusedindetergentsandothernon-fertilizerapplications.White

PhosphorusDriver,J.,Lijmbach,D.,andSteen,I.(1999).WhyRecoverPhosphorusforRecycling,

andHow?EnvironmentalTechnology,20,651–662.From

Wastewater

in

Mixed

TanksTECHS

FOR

P-RECOVERYPHOSPAQ&ANPHOSBoththePHOSPAQandANPHOSprocessesaredevelopedintheNetherlandsfortheprecipitationofstruvite.ThePHOSPAQprocess,developedbyPaques,takesplaceinoneaeratedCSTR.Asaresultofaeration,thepHincreasesbycarbondioxidestrippingandprovidesmixing.Additionally,magnesiumoxideisaddedtothereactortoremovephosphateasstruviteatapHof8.2–8.3.Thestruviteisharvestedfromthebottomofthereactorandtransferredintoacontainerbymeansofascrewpress.Thedryweightoftheharvestedstruviteisaround75%andthecrystalshaveanaveragesizeofaround0.7mm(Driessenetal.,2023).Figure

4.

Process

scheme

of

PHOSPAQDriessen,W.,Abma,W.,VanZessen,E.,Reitsma,G.,andHaarhuis,R.(2023).Sustainabletreatmentofrejectwaterandindustrialeffluentbyproducingvaluablebyproducts.14thEuropeanBiosolidsandOrganicResourcesConference.Leeds,UK.From

Wastewater

in

Mixed

TanksTECHS

FOR

P-RECOVERYPHOSPAQ

&

ANPHOSTheANPHOSprocessisoperatedinbatch

intwoseparatereactors.

Afterthereactionthestruviteisprecipitated,

dewatered

anddried.Theinstallation

isplacedinbetweentheanaerobictreatmentandaerobictreatmentof

thewastewatertreatmentplant.Thestruvitethatisobtainedduringtheseprocessesarefine

crystals

thathavethestructureofsand.Thestruvitewasfirstclassifiedasasecondary

rawmaterialandexportedaswastetoGermanywhereitisused

asrawmaterialfortheproduction

of

fertilizers

ormixedwithotherfertilizers

toobtainagoodnutrientcontent.Figure

4.

Process

scheme

of

PHOSPAQDriessen,W.,Abma,W.,VanZessen,E.,Reitsma,G.,andHaarhuis,R.(2023).Sustainabletreatmentofrejectwaterandindustrialeffluentbyproducingvaluablebyproducts.14thEuropeanBiosolidsandOrganicResourcesConference.Leeds,UK.NuReSysstandsforNutrient

Recycle

System

andisoperatedintworeactors.TheNuReSysprocessdiffersfromtheANPHOSprocesssinceitisoperated

incontinuousmodeinsteadofbatchatalowerresidencetime.Another

differencewiththeANPHOSprocessistheuseofMgCl2asamagnesium

sourceandtheadditionofa29%NaOHsolutiontothecrystallizationreactor

insteadofusingMgO.Thecrystallizationtankisequippedwithasimple

bladeimpellerandaspecificdevelopedandfullyautomatedcontrolalgorithm

ensuresanoptimalpH(8–8.5),reagentdosingandvaryingmixing

intensity.Inthiswaythegrowthofnovelcrystallinematteruponexisting

crystals

occursandpreventsunwantedimpellerorreactorscaling.NuReSysFrom

Wastewater

in

Mixed

TanksTECHS

FOR

P-RECOVERYFigure5.SchematicoverviewoftheNuReSysprocess(modifiedfromMoermanetal.,2023).Moerman,W.,Carballa,M.,Vanderkerckhove,A.,Derycke,D.,andVerstraete,W.(2023).Phosphateremovalinagro-industry:Pilotandfull-scaleoperationalconsiderationsofstruvitecrystallization.Waterresearch,43,1887–1892.PHOSNIXThePhosnixprocessisasidestreamprocessthatenableseffectivephosphateremovalandrecoveryfromthedigesterwastewaterofthesludgetreatmentprocessasgranulatedstruvite(UenoandFuji,2023;Nawa,2023).

Thewastewaterisfedintothebottomofafluidizedbedreactor.Thecolumncontainsabedofgranulatedstruvite,whichactsasaseedmaterialforcrystalgrowth.Magnesiumhydroxideisaddedinamagnesiumtophosphateratioof1:1andthepHisadjustedto8.2–8.8withtheadditionofsodiumhydroxideandbyairstripping(UenoandFuji,2023).Acrystalretentiontimeof10daysallowsthegrowthofpelletsbetween0.5and1.0mminsize,afterwhichtheyarepurgedfromthebottomofthereactorcolumn.Finegranulesofstruviteintheseparatedliquidarereturnedtothereactioncolumntoprovidenewseedmaterialinordertoassurethecontinuityoftheprocess(UenoandFuji,2023;Ueno,2023).Thelargerpelletsarefedintoahopperwherethewatercontentisreducedtolessthan10%.From

Wastewater

in

Fluidized

Bed

ReactorsTECHS

FOR

P-RECOVERYNawa,Y.(2023).P-recoveryinJapan–thePHOSNIXprocess.BALTIC21–PhosphorusRecyclingandGoodAgriculturalManagementPractice,Berlin.Ueno,Y.(2023).FullscalestruviterecoveryinJapan.In:Valsami-Jones,E.(Ed.),Phosphorusinenvironmentaltechnology:Principlesandapplications.London:IWA,p.496–506.Ueno,Y.,andFuji,M.(2023).Threeyearsexperienceofoperatingandsellingrecoveredstruvitefromfullscaleplant.EnvironmentalTechnology,22,1373–1381.CrystalactorFrom

Wastewater

in

Fluidized

Bed

ReactorsTECHS

FOR

P-RECOVERYTheCrystalactorwasoriginallydevelopedtoremovecalcium

fromdrinkingwater.

And

EBPRistreatedintheCrystalactortoconcentratethephosphateinasidestream.Thephosphaterichflowiscollectedinbuffertanks.Ascarbonatesinhibitcalciumphosphateprecipitation,theyareremovedinacascadestripperbeforethewastewaterflowenterstheCrystalactor.The

Crystalactorconsistsofacylindricalfluidizedbedreactorinwhichfiltersandisusedasseedmaterial.Thestrippedwastewaterispumpedthroughthereactorinanupwarddirection,andatsuchahighvelocitythepelletbediskeptinafluidizedstate.EfficientcalciumphosphatecrystallizationrequiresapHof9.Therefore,Ca(OH)2solutionisaddedtothereactorandthedosageiscontrolledbypHmeasurement.Asthepelletsgrowinsizeandmass,theysinktothebottomofthereactor.Therecoveryratecanreach70–80%(CornelandSchaum2023).Cornel,P.,andSchaum,C.(2023).Phosphorusrecoveryfromwastewater:needs,techniquesandcosts.WaterScienceandTechnology,59,1069–1076.PEARL

&

WASSTRIPThePERALprocessrecoversstruvitefromthesludgeliquorofananaerobicdigester,ingfromaWWTPwithbiologicalphosphorusremoval.Thetechnologyisbasedoncontrolledchemicalcrystallizationinanup-flowfluidizedbedreactorwithmultiplereactivezonesofincreasingdiameters.Theprocesshastheadvantageofallowinglargestruvitepelletsfrom1.5to4.5mmindiametertobekeptinsuspensioninthebottomofthereactorwithoutwashingoutfinecrystalnucleifromthetopofthereactor.Struvitecrystallizationiscontrolledbyabinationofmagnesiumdose,pHcontrolandbymeansofatreatedeffluentrecycle(Kochetal.,2023).WASSTRIPstandsforWasteActivatedSludgeStrippingandisdesignedtoremoveinternalphosphorus.Thisbinationofthetwoprocessesresultsinahigherstruviteproductionandpreventsscalinginthedigesterandthedewateringapparatus.From

Wastewater

in

Fluidized

Bed

ReactorsTECHS

FOR

P-RECOVERYBritton,A.(2023).P-recoveryinNorthAmerica–Ostara’sPEARLTMprocess.PhosphorusRecyclingandGoodAgriculturalManagementPracticeBerlin,Germany,September28–30.Koch,F.A.,Mavinic,D.S.,Yonemitsu,N.,andBritton,A.T.(2023).Fluidizedbedwastewatertreatment.U.S.PatentNo.7622047B2.75%70%55%AIRPREXSEABORNETHERMOCHEMICAL

&

ELECTROTHERMALpH

increases

by

stripping

carbon

dioxideInternal

recycle

allows

the

structive

crystal

to

grow.The

recovered

struvite

quality

is

conform,

except

for

the

water

solubility.An

acidification

of

the

sludge

by

the

addition

of

sulfuric

acidThe

sulfur-rich

digester

gas

is

used

to

precipitateNutrient

are

recycled

Forthedryprocess,phosphorusis

recoveredbymeltingtheash.Used

assecondary

materialinthephosphateindustryfortheproductionofelementary(white)

phosphorusTwothermalprocesses

arerunningfullscale.Theremainingash(afterP-recovery)canbemixedwithcement

or

concrete.Bricksorsomeotherobjectscanbemadeofashortheashcanbe

melted

andsolidifiedasaceramic

materialSewage

Sludge

(Ash)From

Sewage

Sludge

(Ash)TECHS

FOR

P-RECOVERY4PARTFOURDISCUSSIONDISCUSSIONThe

Liquid

Phase

Vs.

The

Sludge

(Ash)The

Liquid

PhaseThe

Sludge

(Ash)a

simple

processrecycled

rate

40-50%Structive

or

calcium

phosphate

percipitated

in

a

stirred

tank

reactor

(much

simpler

to

operate)

or

fluidized

bed

reactor.Calcium

phosphate

are

seldom

used

at

full

scalea

complex

processhigher

recovery

rateslarge

amount

of

chemicals

and/or

energy

and

process

steps

requiredhigh

investment

and

operational

costsADDYOURTEXTSimpletechniquessuchastheprecipitationofphosphatefromtheliquidphaseseemtobepreferred(Satoriusetal.,2023),i.e.lesscostlyapproachesevenattheexpenseofloweryields.Phosphorusrecyclingfromashhastobeconsidered,forthehighcostofincinerationisnotassignedtotherecoveryofphosphorus.aluminumsaltsareproposedasanalternativetoprecipitatephosphatefromthewastewater.thephaseoutofthedirectuseofsludgetofarmlandinmanycountries.Theuseofphosphorusrecoverytechniqueswillincreaseinthefuture.Inthatcase,theuseofalternativeenergywouldbebeneficialifstruviteisprecipitatedfromwastewater.DISCUSSIONFuture

PerspectivesSatorius,C.,vonHorn,J.,andTettnborn,F.(2023).Phosphorusrecoveryformwastewater:ExpertsurveyonPresentuseandfuturepotential.WaterEnvironmentResearch,84,313–323.DISCUSSIONConclusionTherecovery

source

ofphosphorus

must

include

municipal

and

industrialwastewaterandsubsequentlyusingitasafertilizer.P-recoveryhasbeenwidelystudiedandanumberoffull-scaleinstallations

forP-recoveryarealreadyoperational,showingthat

P-recoveryistechnicallyfeasiblePhosphatecanberecoveredfromthe

liquidphase

(40-50%

recovery

rate),sludgephase(ash;

80-90%)

of

awastewatertreatmentplant.

P-recoveryfromtheliquidphaseisasimpleprocess,whereasP-recovery

fromthesewagesludgeashhasahigherenergyconsumptionandhigher

investmentcost.Themostappropriatewayvaries.Britton,A.(2023).P-recoveryinNorthAmerica–Ostara’sPEARLTMprocess.PhosphorusRecyclingandGoodAgriculturalManagementPracticeBerlin,Germany,September28–30.Cordell,D.,Rosemarin,A.,Schr¬oder,J.J.,andSmit,A.L.(2023).Towardsglobalphosphorussecurity:Asystemsframeworkforphosphorusrecoveryandreuseoptions.Chemosphere,84,747–758.Cornel,P.,andSchaum,C.(2023).Phosphorusrecoveryfromwastewater:needs,