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Thisarticlewasdownloadedby:[InnerMongoliaUnivofST]On:28May2013,At:02:01Publisher:Taylor&FrancisInformaLtdRegisteredinEnglandandWalesRegisteredNumber:1072954Registeredoffice:MortimerHouse,37-41MortimerStreet,LondonW1T3JH,UKJournalofEnvironmentalScienceandHealth,PartA:Toxic/HazardousSubstancesandEnvironmentalEngineeringPublicationdetails,includinginstructionsforauthorsandsubscriptioninformation:(CAST)YaY.Wanga,ZhaoX.Zhanga,MinYana,NaiY.Gaoa,JianYanga&MingH.RenaaStateKeyLaboratoryofPollutionControlandResourcesReuse,CollegeofEnvironmentalScienceandEngineering,TongjiUniversity,SipingRoad,Shanghai,P.R.ChinaPublishedonline:28Jan2010.Tocitethisarticle:YaY.Wang,ZhaoX.Zhang,MinYan,NaiY.Gao,JianYang&MingH.Ren(2010):Impactofoperatingconditionsonnitrogenremovalusingcyclicactivatedsludgetechnology(CAST),JournalofEnvironmentalScienceandHealth,PartA:Toxic/HazardousSubstancesandEnvironmentalEngineering,45:3,370-376Tolinktothisarticle::(2010)45,370–376CopyrightC
Taylor&FrancisGroup,LLCISSN:1093-4529(Print);1532-4117(Online)DOI:10.1080/10934520903467964Impactofoperatingconditionsonnitrogenremovalusingcyclicactivatedsludgetechnology(CAST)YAY.WANG,ZHAOX.ZHANG,MINYAN,NAIY.GAO,JIANYANGandMINGH.RENStateKeyLaboratoryofPollutionControlandResourcesReuse,CollegeofEnvironmentalScienceandEngineering,TongjiUniversity,SipingRoad,Shanghai,P.R.ChinaInthisstudy,thenitrogenremovalperformanceofamunicipalwastewatertreatmentplantthatemployscyclicactivatedsludgetech-nology(CAST)wasevaluated.Theimpactofkeyoperationalconditionssuchastemperature,dissolvedoxygen(DO)concentrationsandoperatingmodeswereexaminedinparallel.Duringsummer,whentheoperatingtemperaturerangedfrom27–30◦C,theNH+4-Nandtotalnitrogen(TN)removalefficiencieswere51±7%and42±7%,respectively,andsimultaneousnitrificationanddenitrification(SND)wasconsideredtobethemajornitrogenremovalmechanism.Incontrast,atalowoperatingtemperatureof10–15◦C,theDOconcentrationincreasedfrom0.7to3.0mg/L;however,theNH+4-NandTNremovalswerebothinefficientduetopoorbiomassactivities,whichwasdemonstratedbyalowerspecificoxygenuptakerate(SOUR)of1.2mgO2/gSS·h(15◦C).Moreover,a3h-modefortheCASTprocesswaspreferableduringwinterbecausetheeffluentwastewaterqualitywassimilartothatobtainedwhenthe4h-modewasused.TheextremelyloworganicloadingwastheprimaryreasonforthepoorbioactivityofthesludgeintheCASTsystem,andthiseventuallyledtodeteriorationofthenitrogenremovalefficiencies.Keywords:Cyclicactivatedsludgetechnology(CAST),municipalwastewatertreatment,nitrogenremoval,operatingmodes,simulta-neousnitrificationanddenitrification(SND).IntroductionCyclicactivatedsludgetechnology(CAST)generatedfromthesequencingbatchreactor(SBR)technologyconsistsofacombinationofabiologicalselectorandavariablevolumeprocessreactor.CASTsystemsarecharacterizedbycontin-uousinflowandperiodicaerationaswellasanadditionalsludgereturnfacility.Thisinnovativetechnologyutilizesasimplerepeatedtime-basedsequencethatnormallycon-sistsoffourhourspercyclecomposedoftwohoursoffill-aeration,onehouroffill-settleandonehourofdecanting.[1]Thesethreestepsareoperatedcontinuouslyinacompart-mentedvariablevolumereactorinwhichaninitialreactionvolumeactsasabiologicalselec.[2]ThespecificoperatingmodeimpartsmanyadvantagestoCASTprocesses,includ-inghighoperatingflexibility,lowoperatingcost,efficientnutrientremovalandlessfilamentousbulking.[1]AnotherimportantadvantageofCASTsystemsisthatsimultane-ousnitrificationanddenitrification(SND)canbeaccom-plishedbyoperatingatlowDOconcentrations.[3,4]SNDAddresscorrespondencetoYayiWang,CollegeofEnvironmentalScienceandEngineering,TongjiUniversity,P.R.China;E-mail:[e-mail]4,2009.isanattractivealternativetechnologyforN-removalduetoitspotentialtoeliminatetheneedforseparatetanksasrequiredinconventionaltreatmentplants,whichresultsinsimplifiedandsmallerplants.[5,6]CASTprocesseshavebeenasolutionforthetreatmentofindustrialandmunicipalwastewaterworldwide.Therefore,itisnotsurprisingthatCASThasbeenusedinlarge-scaletreatmentfacilitiesthroughoutNorthAmerica,EnglandandGermany,aswellasinpartsofAsiaandAustralia.[7]Basedonthecomparativelylowinve