Combininganoxicdenitrifyingabilitywithaerobic

InternationalBiodeterioration&Biodegradation57(2006)121–128Combininganoxicdenitrifyingabilitywithaerobic–anoxicphosphorus-removalexaminationstoscreendenitrifyingphosphorus-removingbacteriaHoi-PingShi,Chi-MeiLee
DepartmentofEnvironmentalEngineering,NationalChung-HsingUniversity,No.250,GuoguangRd.,NanChiu,Taichung,Taiwan402,ROC.Received3October2005;receivedinrevisedform2January2006;accepted6January2006AbstractAnaerobic–aerobic(oranaerobic–anoxic)enhancedbiologicalphosphorus-removal(EBPR)processesweregenerallyconsideredforPremoval.However,someisolatedpolyphosphate-accumulatingorganisms(PAOs)ordenitrifyingP-removalbacteria(DPB)mayhavevariedP-removalcharacteristicsunderdifferentconditions.ThisstudyinvestigatedproperscreeningproceduresforisolatingDPBfrompiggerysludge,enrichedsludge,andwinerysludge.Wecombinedanoxicdenitrifyingabilitywithaerobic–anoxicP-removalexaminationstoscreentheDPBsascomparedwithconventionalanaerobic–aerobicandanaerobic–anoxicP-removalexaminations.Itwasconcludedthatdenitrificationabilitydetectionwasrecommendedasthefirststepofscreening.Subsequently,denitrifierswereculturedunderanaerobic–anoxicsingle-stageprocessusingoxygenandnitratesimultaneouslyase
acceptorstoexamineP-removalabilities.Wechosesingle-stageaerobic–anoxicP-uptakedenitrifiers(TypesIandII)accordingtothepurposeofPremoval,whereaswell-growndenitrifierswithoutobviousPremovalmightbeinducedbyconsiderablePHBformation.Moreover,underanaerobic–anoxicP-removalexaminations,mostoftheisolatedDPBshadnoobviousanaerobicPrelease,butdidhavesignificantanoxicPuptake.PureisolatedDPBculturesbehavedlikeenrichedsludge,whichshowednoanaerobicPreleasebutachievedrespectiveN-andP-removalefficienciesof96%and86%.r2006PublishedbyElsevierLtd.Keyword:Anaerobic–aerobic(oranaerobic-anoxic)processes;Denitrifyingphosphorus-removalbacteria;P-removalmechanism;Polyphosphate1.IntroductionPhosphorus(P)removalfromwastewatercanbeachievedbychemicalprecipitation,orbybiologicalmechanismsinaprocesscalledenhancedbiologicalphosphorusremoval(EBPR).SeveralresearchershavereportedthatP-removalmechanisminEBPRprocessesincludesanaerobicPreleaseandaerobicPuptake(Minoetal.,1987;Comeauetal.,1987).Polyphosphate-accumu-latingorganisms(PAOs)involvedinanaerobic-aerobicEBPRprocessesarecapableofphosphateuptakeinexcessoftheirmetabolicrequirementsandstorephosphateintern-allyaspolyphosphate(poly-P)polymers.SeveralinvestigatorshavementionedthatnitrateisbeneficialforbiologicalP-removalprocesses(vanLoosdrechtetal.,1992;Kerrn-JespersenandHenze,1993;Kubaetal.,1993,1994;Wagneretal.,1994).DenitrifyingP-removalbacteria(DPB)capableofPremovalunderalternatinganaerobic–anoxicconditionshavethesamepotentialforPremovalasconventionalaerobicP-removalbacteriainanaerobic–aerobicprocesses(Kubaetal.,1993).DPBwererecentlyisolatedtoinvestigatetheP-removalmechanismsinanaerobic–anoxicprocesses.Poly-Paccu-mulationbyParacoccusdenitrificanswasexaminedunderaerobic,anoxic,andanaerobicconditionsandinthepresenceofanexternalcarbonsource.ItwasconcludedthatthecombinationofPandNremovalscanbecompletedwithoutalternatinganaerobic/aerobicoranaerobic/anoxicswitches(BarakandvanRijn,2000a).Moreover,thepoly-PaccumulatingdenitrifierPseudomonassp.JR12wasalsoisolatedandexhibitedsimilarP-removalbehavior(BarakandvanRijn,2000b).ARTICLEINPRESS:10.1016/j.ibiod.2006.01.001
Correspondingauthor.Tel:[phone];fax:[phone].E-mailaddresses:[e-mail],[e-mail](H.-P.Shi),[e-mail](C.-M.Lee).Anaerobic–aerobic(oranaerobic–anoxic)EBPRpro-cessesweregenerallyconsideredforPremoval.However,someisolatedPAOsorDPBmighthavevariedP-removalcharacteristicsunderdifferentconditions(Nakamuraetal.,1995a,b;vanNieletal.,1999;BarakandvanRijn,2000a,b;Mullanetal.,2002),andtheremightbedisagreementoverP-removalmechanismsunderdifferentcultureconditions.ThisstudyattemptedtoisolateDPBfrompiggeryandwinerysludgebycombininganoxicdenitrifyingabilitywithaerobic–anoxicP-removalexam-inationstoscreentheDPBs.Furthermore,alternatinganaerobic–anoxicsemi-continuousbatchP-removalexam-inationswereusedtoclarifythesignificanceofanaerobicmechanismcomparedwithconventionalEBPRprocess.2.Materialsandmethods2.1.ActivatedsludgeandenrichmentreactorThreetypesofactivatedsludgewereselectedforDBPisolation:(1)rawpiggerysludge,(2)winerysludge,and(3)enrichedsludgefrompiggerysludge.Eachsludgesourcehaduniqueenvironmentalcharacteristics.Thepiggerysludgewasobtainedfromananaerobic–aerobicsequencebatchreactor(AO-SRB)wastewatertreatmentsystem,includinganaerobi-c–aerobicreactorandreturnedsludge.Thewinerysludge,obtainedfromthereturnedsludgeofthewinerywastewatertreatment,hadpronouncedpoly-PobservedviaDAPIstaining(Streichanetal.,1990).Theenrichedsludgewasobtainedfromanalternatinganaerobic–anoxiclab-scalechemostatoperatedfor1monthbyinoculatingrawpiggerysludge.The2-LchemostatforDPBenrichmentwasoperatedat301Cfora24-hcycle.Eachcycleconsistedoftwophases:a4-hanaerobicstageanda20-hanoxicstage.Thesyntheticmedium