复合生物反应器亚硝酸型同步硝化反硝化脱氮英文王建龙

ChineseJournalofChemicalEngineering,16(5)778—784(2008)NitrogenRemovalbySimultaneousNitrificationandDenitrificationviaNitriteinaSequenceHybridBiologicalReactor*WANGJianlong(王建龙),PENGYongzhen(彭永臻)**,WANGShuying(王淑莹)andGAOYongqing(高永青)CollegeofEnvironmentalandEnergyEngineering,BeijingUniversityofTechnology,Beijing100022,ChinaAbstractSequencehybridbiologicalreactor(SHBR)wasproposed,andsomekeycontrolparameterswerein-vestigatedfornitrogenremovalfromwastewaterbysimultaneousnitrificationanddenitrification(SND)vianitrite.SNDvianitritewasachievedinSHBRbycontrollingdemandoxygen(DO)concentration.Therewasapro-grammeddecreaseoftheDOfrom2.50mg·L－1to0.30mg·L－1,andtheaveragenitriteaccumulationrate(NAR)wasincreasedfrom16.5%to95.5%in3weeks.Subsequently,furtherincreaseinDOconcentrationto1.50mg·L－1didnotdestroythepartialnitrificationtonitrite.Theresultsshowedthatlimitedairflowratetocauseoxygendefi-ciencyinthereactorwouldeventuallyinduceonlynitrificationtonitriteandnotfurthertonitrate.NitrogenremovalefficiencywasincreasedwiththeincreaseinNAR,thatis,NARwasincreasedfrom60%to90%,andtotalnitrogenremovalefficiencywasincreasedfrom68%to85%.TheSHBRcouldtoleratehighorganicloadingrate(OLR),CODandammonia-nitrogenremovalefficiencyweregreaterthan92%and93.5%,respectively,anditevenoper-atedunderlowDOconcentration(0.5mg·L－1)andmaintainedhighOLR(4.0kgCOD·m－3·d－1).Thepresenceofbiofilmpositivelyaffectedtheactivatedsludgesettlingcapability,andsludgevolumeindex(SVI)ofactivatedsludgeinSHBRneverhitmorethan90ml·g－1throughouttheexperiments.Keywordsnitrogenremoval,simultaneousnitrificationanddenitrification,nitriteaccumulation,demandoxygen,pH1INTRODUCTIONBiologicalnitrification-denitrificationisthemostcommonlyusedprocessfornitrogenremovalfromwastewater.Nitrificationistheautotrophicoxidationof4NH+-N,firstto2NO−-Nandthen,to3NO−-N,whereasdenitrificationistheheterotrophicandanoxicconversionof3NO−-N,firstto2NO−-Nandthen,togaseousnitrogencompounds[1].Therefore,twosepa-ratereactorsarerequiredtoprovidedifferentenvi-ronmentsforthetwokindsofbacteria:nitrifiersanddenitrifiers,suchasconventionalanoxic/oxicprocess.However,inrecentyears,thephenomenonofsimul-taneousnitrificationanddenitrification(SND)hasbeendescribedforvarioussystems[2,3].Suchproc-esseseliminatetheneedoftwoseparatereactors,thus,simplifythetreatmentsystem.Varioustypesoftreat-mentunitshavebeenproposedsofartorealizesuchasystem[4].Someothernovelnitrogenremovalprocesseshavearisenduringthelastfewyears,suchasshort-cutnitrificationdenitrificationandanaerobicammoniumoxidation(ANAMMOX)[5-7].Theshort-cutprocessisbasedonthefactthatnitriteisanintermediarycompoundinbothsteps:nitrificationanddenitrifica-tion.Thisapproachleadstosavingsofoxygenduringnitrificationandareductionoforganiccarbonre-quirementduringdenitrification,whichreducesthecostsfornitrogenremoval.Investigationoftheshort-enednitrogenremovalpathwayvianitriterevealed:(1)40%reductionofCODdemandduringdenitrification;(2)63%higherrateofdenitrification;(3)300%lowerbiomassyieldduringanaerobicgrowth;and(4)noapparentnitritetoxicityeffectsforthemicroorganismsinthereactor[8,9].IfSNDisaccompaniedbythein-hibitionofnitriteoxidizedtonitrate,theoreticallyasavingoforganicenergyofupto40%couldbereal-ized[9].Yooetal.[3]achievedtheSNDvianitritebycontrollingtheDOinanintermittently-aeratedsus-pendedreactor.Gaoetal.[10]observedthephe-nomenonofSNDvianitriteinthesuspendedSBRreactor,andthemaximumSNDefficiencyreachedupto54.6%bycontrollingtheDO.AlltheseresultsshowedthatitisfeasibletorealizetheSNDvianitritebycontrollingcertainoperationconditions.Theobjectiveofthisresearchistoextendtheconventionalsuspendedactivatedsludgenitrogenre-movalunitforSNDtoactivatedsludgeandbiofilmcombinedsystem.Asequencehybridbiologicalreac-tornitrogenremovalprocessutilizingSNDvianitritewasproposed,withoutananoxicperiod,toevaluateitsperformance.Somekeycontrolparametersandtheiroptimalvaluesweredeterminedinthelaboratorytoanalyzeandinvestigatetherelativeimportanceoffactorsaffectingnitriteaccumulationinthesequencehybridbiologicalreactor(SHBR)reactor.2MATERIALSANDMETHODS2.1ReactorsystemAschematicdiagramoftheexperimentalSHBRisshowninFig.1.Thereactorwasacolumntank,withamaximumworkingvolumeof12L.Thereactorwasequippedwithanaerator,aperistalticpump,aswellasprobestofollowvariationsofpHandDOconcentration.Allexperimentswereconductedatam-bienttemperature(23-25°C).MixedliquorsuspendedReceived2007-10-18,accepted2008-04-20.*SupportedbytheNationalKeyProjectofScientificandTechnicalSupportingProgramofMinistryofScienceandTechnologyofChina(2006BAC19B03),AcademicHumanResourcesDevelopmentinInstitutionsofHigherLeadingundertheJurisdictionofBeijingMunicipality,andtheSpecializedResearchFundfortheDoctoralProgramofHigherEducationofChina(20060005002).**Towhomcorrespondenceshouldbeaddressed.E-mail:[e-mail].,Vol.16,No.5,October2008779solids(MLSS)concentrationofSHBRwasmain-tainedapproximatelyat1500mg·L－1throughouttheexperimentalperiods.Thereactorwasoperatedintoquasisteadystatebeforedetailedexperiments(de-scribedbelow)comme