含铁污泥处理

Thisarticlewasdownloadedby:[BeijingUniversityofTechnology]On:15April2012,At:19:43Publisher:Taylor&FrancisInformaLtdRegisteredinEnglandandWalesRegisteredNumber:1072954Registeredoffice:MortimerHouse,37-41MortimerStreet,LondonW1T3JH,UKEnvironmentalTechnologyPublicationdetails,includinginstructionsforauthorsandsubscriptioninformation:‐dosedwasteactivatedsludgebyanaerobicdigestionD.K.Johnsona,C.M.Carliell‐Marqueta&C.F.ForsteraaSchoolofEngineering,UniversityofBirmingham,Edgbaston,Birmingham,B152TT,UKAvailableonline:17Dec2008Tocitethisarticle:D.K.Johnson,C.M.Carliell‐Marquet&C.F.Forster(2003):Anexaminationofthetreatmentofiron‐dosedwasteactivatedsludgebyanaerobicdigestion,EnvironmentalTechnology,24:8,937-945Tolinktothisarticle::©SelperLtd,2003ANEXAMINATIONOFTHETREATMENTOFIRON-DOSEDWASTEACTIVATEDSLUDGEBYANAEROBICDIGESTIOND.K.JOHNSON,C.M.CARLIELL-MARQUETANDC.F.FORSTER*SchoolofEngineering,UniversityofBirmingham,Edgbaston,BirminghamB152TT,UK(Received22August2002;Accepted20February2003)ABSTRACTAnaerobicdigestionisanimportantsludgetreatmentprocessenablingstabilisationoftheorganicfractionofsewagesludgepriortolandapplication.AnypracticewhichmightretardtheanaerobicdigestionprocesswilljeopardizethestabiKtyoftheresultingdigestedsludge.Thispaperreportsonaninvestigationintotherelativedigestibilityofiron-dosedwasteactivatedsludge(WAS)fromasewagetreatmentworks(STW)withchemicalphosphorusremoval(CPR),incomparisontoWASfromaworkswithoutphosphorusremoval.Twolaboratoryscaleanaerobicdigesters(51)werefedinitiallywithnoniron-dosedWAS(WorksM)atasolidsretentiontimeof19days.After2monthstheiron-dosedCPRsludge(WorksR)wasintroducedintotheseconddigester,resultingina32%decreaseinbiogasproductionandanincreaseinthemethanecontentofthebiogasfromanaverageof74%to81%.Pre-treatmentoftheCPRsludgewithsodiumsulphideandshear,bothaloneandincombination,causedthegasproductiontodeterioratefurther.Pre-acidificationandpre-treatmentwithEDTAdidresultinanenhancedgasproductionbutitwasstillnotcomparablewiththatofthedigesterbeingfedwithnon-iron-dosedsludge.Thedailygasproductionwasfoundtobelinearlyrelatedtotheamountofboundironinthesludge.Keywords:Activatedsludge,irondosing,anaerobicdigestion,gasproduction.INTRODUCTIONThephasingoutofthemarinesitesforthedisposalofsludgein1998meantthattherewasaneedtofindadditionaldisposalroutesforsome200,000tonnesofsludgeeachyearintheUK.Traditionally,asignificantproportionofthesludgeproducedduringthetreatmentofmunicipalsewagehasbeenappliedtoagriculturallandandthisisstillconsideredtobetheBestPracticalEnvironmentalOption[1].However,thecombinationofincreasedenvironmentalawareness,publicconcernandEuropeanlegislationhasresultedinattentionbeingre-focussedonmanyaspectsofsludgeprocessing.Arguably,themostsignificantaspectswhichmustbeconsideredaretherequirementsoftheSafeSludgeMatrix,togetherwiththeproposedEUDirective,theMunicipalWastewaterTreatmentDirectiveandtheCodesofPracticeforAgriculturalUseofSewageSludge[2,3].Inotherwords,thereisaneedtoconsiderthestabilityofthesludgeandthefateofinorganicnutrients,particularlyphosphate.Theremovalofphosphatefrommunicipalsewagecanbeachievedbiologically[4,5]orbytheuseofinorganicsalts,suchasferroussulphate,toforminsolublephosphateswhichcanthenberemovedbysettlement[5,6].Intheactivatedsludgeprocess,theseinorganicphosphatesareincorporatedintothesludgefloesandchangetheircharacteristicsappreciably.Theprecisespeciationoftheironwhichisformedinthesludgefloeswhenphosphateisremovedinthiswayisnotclearbutitislikelytobeacomplexhydroxyironphosphate[7].Mesophilicanaerobicdigestionhasalwaysbeenoneoftheoptionsfortreatingsewagesludgepriortolandapplicationinthatitstabilisestheorganicfractionofthesludgeand,whilsttherewillbeaneedtoconsideradditionalpasteurisingprocessesforsomesludgestoconformtothespecificationsforextendedtreatment[2],itislikelytohaveanappreciableroleforsometime.Wasteactivatedsludgeswhichhavebeengeneratedinachemicalphosphateremoval(CPR)processwillalsohavetobetreatedbyanaerobicdigestiontoacquirethestatusoftreatedsludgeasdefinedbytheSafeSludgeMatrix.Althoughsomeearlierworkhasshownthatthistypeofsludgewillhavenoeffectondigestion[8,9],thereisastrongbodyo