Cyclicactivatedsludgetechnologyrecentoperatin

CYCLICACTIVATEDSLUDGETECHNOLOGY-RECENTOPERATINGEXPERIENCEWITHA90.000PEPLANTINGERMANYGunnarDemoulin*,AndreasRüdiger**,MervynC.Goronszy****SFCUmwelttechnik,JuliusWelserStr.15,A-5020Salzburg**AQUABIOTECGmbH,Maria-Goeppert-Straße1,D-23562Lübeck***TriTechInc.,P.O.Box189,LakeForest,CA92630,USAABSTRACTCyclicactivatedsludgetechnologywasselectedforthePotsdamWastewaterTreatmentPlant(90,000p.e.).Thecyclicactivatedsludgefacilitycomprisesfourmodulesintegratedintotwocircularbasins.ConstructionwascommencedinFebruary1998withseedingoftheplantforstartuptakingplaceinOctober1998.ProcessperformancehasbeenmetsinceSpring1999at80-90percentofdesignload.Inordertooptimizestart-upprocedures,respirationrateswereusedasaguidanceforprocessstabilizationandonlineprocessoptimizationduringnormaloperation.Operationforco-currentnitrificationdenitirificationprovidedanammoniaremovalof1.1mgNH4-N/gMLSS.h(150C)andacorrespondingnitraterespirationrateof0.85mgNO3-N/gMLSS.hunderaeratedconditions.Enhancedbiologicalphosphorusremovalgeneratedaneffluentmeantotalphosphorusconcentrationof0.38mg/Lwithoutprecipitantaddition.KEYWORDSCyclicactivatedsludgetechnology,CYCLAZURTM,SBR,operationexperience,co-currentnitrificationanddenitrification,phosphorusremoval.BACKGROUNDOverrecentyearstwodifferentgroupsofcyclicactivatedsludgeprocesseshavegainedincreasingimportanceinwastewatertreatment.OnegroupencompassestheprocessfamilyofCyclicActivatedSludgeTechnologieswhichrepresentsacertaintechnicaldevelopmentofaprocessphilosophy(Goronszy1979,1985,Demoulinetal1997,1999).ThisprocessfamilyisappliedinlargescaletreatmentthroughoutGermany,England,NorthAmerica,partsofAsiaandAustralia.Indifferentcountriesdifferenttradenamesareusedsuchase.g.CYCLAZURTMforPotsdamWWTP.ThesecondgroupofprocesseshasbeenmadepopularthroughtheworkofIrvine(Irvineet.al.,1983)andWilderer(Wildereret.al.,1986)andareknownbytheacronymofSBR(sequencingbatchreactor).SBRmethodologyisverycommonlyusedforscientificstudies,benchscaletesting,andfullscaleapplicationsofmainlysmallandmediumsizeplantsworldwide.DEVELOPMENTOF“CYCLICACTIVATEDSLUDGETECHNOLOGY“ThedevelopmentofthistechnologystartedinAustraliaasearlyas1965(Goronszy,1979).Inviewofthedesignatedapplicationforlargescaleplantsandtheusageoftheprocessadvantagesofferedbytheco-currentnitrification/denitrification(co-N/DN)thefollowingprocessfeaturesweredeveloped:-Shortcycletimes(4hoursandless),introductionofbiologicalselectorzonesusingtransversepartialbafflewalls,fillsequenceregulationforfilamentoussludgebulkingcontrolandco-currentnitrification/denitrification,meansofregulatingthekineticsofoxidationreductionpotentialdepletionforenhancedbiologicalphosphorusremoval(EBPR)(Goronszyetal1991).Throughprocessoperationforco-currentnitrification/denitrificationformalizedmixingsequencesandequipmentwereomitted.ThebiologicalselectoraddressedprocessneedsforfilamentoussludgebulkingcontrolandEBPR.-Processcontrolusingin-basinrespirationrates,whichallowedpermanentcontrolofthemetabolicactivityofthebiomassandconsequentlychangedtheprinciplesofprocessoperationfromatimebasedcontroltoademandorientedprocesscontrol.-Aclearwaterwithdrawalsystemforhighratedecantingofupto2.5mofsolidsfreeeffluentwithinashorttimefrombasinshavingsurfaceareasofupto8000m2(i.e.multiplebasinsandmultipledecanters).-Establishmentofadjustablenormalandhighflowoperatingprotocols.TheabovementioneddevelopmentswerecommencedinAustraliaandlateradaptedanddevelopedforNorthAmericaclimatesandextendedtomeetlocalclimateanddischargerequirementsofCentralEurope.Coldclimateco-currentnitrification/denitrificationandredoxcontrolledEBPRweredemonstratedintheAustrianGrossarlplant,(Demoulinetal,1997),in1994forthefirsttimeinEurope.ThefirstsuchplantstousethistechnologyinGermanyarethePotsdam(FRG,90,000pe)andNeubrandenburg(FRG,140,000pe)facilities(Demoulinetal,1999)whichcameonlineinearly1999.HISTORYOFSBRTECHNOLOGIESPioneersofwastewatertreatmentprocessingusingactivatedsludgewereArdenandLockett(1914).Becauseautomaticoperationaltaskswereyettobemastered,activatedsludgeprocessingsoonbecameacontinuouslyaeratedprocess.Throughthedevelopmentoftimecontrolledautomationsystems,togetherwithsubmergedaerationdevicesthatwereessentiallynon-foulingledtotheSBRprocess(Irvineetal;1983),(Wildereretal,1986).Thismethodologytypicallycomprisesthefollowingfeatures.-Timecyclesforseparateaerobic,anoxicandanaerobicsequencingwithinthesocalled„reactionphase“forstrictlyseparatednitrification,denitrificationandEBPR.Toobtainthesereactionconditionsinfluentequalizationandmechanicalmixingbecameaprocesscharacteristic-Processcontrolusingcycletimeswithseparateprogramsfordifferentoperatingconditions-Differenttypes,shapesandbrandsofclearwaterwithdrawalsystemsareusedsuchasropeguidedfloatingdecanters,simplesubmergedvalvingequipmentorbafflearrangements.IMPLEMENTATIONOFTHECYCLICACTIVATEDSLUDGETECHNOLOGYATTHEPOTSDAMWWTPThePotsdamfacilitywasdesignedtotreatprimarysettledsewageinafourbasinconfiguration,withanaerobicdigestionofthewastesludgemixture.Thefourbasinsareconfiguredastwo52.5mdiametercircularstructures,eac