高氨氮猪场废水的亚硝酸型脱氮研究英文杨朝晖

ArticleID:1005-0930(2004)02-0161-08　　CLCnumber:X703.1　　Documentcode:A①RemovingtheNitrogenfromHighlyNitrogenousPiggeryWastewaterviaNitriteYANGZhaohui,　GAOFeng,　ZENGGuangming,　XIEGengxin,　LIChen(DepartmentofEnvironmentalScienceandEngineeringofHunanUniversity,Changsha410082,China)Abstract:Anaerobicdigestioniscommonlyusedtoremovetheorganicmatterfromthepiggerywastewater.Completedigestioncanremovemostoftheorganicmattersinthewastewater,butthiscanalsolowertheCOD/NH+4-Nratio(1～3).Basedonthetheoryoftwo-stepdigestion,wecankeephighCOD/NH+4-Nratio(7～10)inthewastewaterbystoppingthedigestionatthestepofhydrolysis,whichbenefitsthedenitrificationlater.Anoxic/AerobicSBRwasusedtotreatthesetwokindsofwastewater.Intheexperimentnitritenitrification/denitrificationwasfound.ThestudyresultsindicatedthatCOD/NH+4-Nratiowasanimportantfactorfornitrogenremoval.Andthenitrogenremovalofpartlydigestedwastewaterwasmoreefficaciousthanthatofthecompletelydigestedwastewater.FurthermoretheeffluentCODconcentrationwasalsolower.Keywords:nitritenitrification/denitrification;Anoxic/AerobicSBR;piggerywastewater;digestAnaerobicdigestioniswidelyusedtoremoveorganicmatterfromhighlyconcentratedwastewaterssuchaspiggerywastewater,becauseofitslowsludgeproductionandlowenergydemands[1-4].Completeanaerobicdigestioncanremovemosttheorganicmatters.Atthemeantime,organicnitrogenouscompoundsinthewastewater,suchasproteinsandaminoacids,areturnedintoammoniawhichcanleadtoexcessiveoxygendemandinthereceivingwater.Theammoniaremovalisneededasapost-treatment,inwhichbiologicalnitrification-denitrificationisthemostwidelyusedprocess[5].ButafterthecompleteanaerobicdigestiontheCOD/NH+4-Nratioofthewastewaterreduces,organiccarboncontentofthedigestedeffluentisnotenoughtofulfillcompletedenitrification,andtheexternalcarbonsourceisthenrequired[6].Theprocessofanaerobicdigestioncanbedividedintotwobasicsteps:(1)hydrolysis12220046　　JOURNALOFBASICSCIENCEANDENGINEERING　　Vol.12,No.2June2004①Manuscriptreceived:2003-10-24;Revised:2004-05-10Foundationitem:SupportedbytheNationalNatureScienceFoundationofChina(No.70171055).Authorbriefintroduction:YANGZhaohui(1963—),Male,Professor.DOI:10.16058/j.issn.1005-0930.2004.02.007andfermentationofcomplexorganicmatterintosimpleorganicacidsandhydrogen,and(2)theconversionoftheorganicacidsandhydrogenintomethane[7].Ifwecanstopthedigestionatthestepofhydrolysis,notonlycanpartoftheorganiccarbonberemovedandthegermwhichcancausediseaseinthewastewaterbekilled,butalsotheCOD/NH+4-Nratiointhewastewatercanremainathighlevel,thentheorganiccarboncontentofthedigestedeffluentwillbesufficienttoachievecompletedenitrification.Nitrogenremovalthroughnitrification-denitrificationcanbeachievedinthenitritepathway(NH+4※NO-2※N2)orthenitratepathway(NH+4※NO-2※NO-3※NO-2※N2).Thenitritepathwayresultsina25%reductionoftheoxygenrequirementsfornitrificationanda40%reductionoftheCODrequirementsfordenitrification.1　MaterialsandMethods1.1　MaterialsThewastewaterfortheexperimentwasobtainedfromUASBreactorfromawastewaterFig.1　Schematicsofthelaboratory-scalereactor1.airpump　2.timecontroller　3.stirrer　4.thermoscope5.effluent　6.sludge　7.influenttreatmentplantofapigfarmlocatedinHunanprovince,China.Themanureinthisfarmwascollectedbywashing.Thetwo-stageanaerobicdigestionUASBreactorwasusedforthewastewatertreatmentplantofthisfarm.HydrolysisstepofanaerobicdigestionmainlytookplaceinthefirstanaerobicdigestionUASBtankandmethane-producingstepofanaerobicdigestionmainlytookplaceinthesecondanaerobicdigestionUASBtank.Table1indicatesthecharacteristicsofthewastewaterfromtwodifferentsourcerespectively.ThecharacteristicsofthetwokindsofwastewaterweresimilarexceptthevalueofCODCrandBOD5.ThelowvalueofCODCrandBOD5inthesecondUASBtankcanbeattributedtothemorecompleteanaerobicdigestionandmostoftheorganiccarbonhadbeenremovedfromthewastewater.Table1　ThequalityofwastewaterWastewatersourceCODCrBOD5NH+4-NNO-x-NpHFirstUASBtank7000～110003000～80001000～14008～127.5～8.5SecondUASBtank2000～35001000～17001000～13007～107.0～8.01.2　ExperimentalequipmentTheschematicsoftheexperimentalequipmentispresentedinFig.1.Tworeactorsofthesamekindwereusedinthisstudy.Thefirstone(SBR1)wasusedtotreatthewastewaterobtainedfromthefirstUASBtankandthesecondone(SBR2)wasusedtotreatthewastewaterobtainedfromthesecondUASBtank.Thereactorhadanactiveliquidvolumeof7.5L.Thetemperaturewaskept162　　　　　　　　　　　　　　Vol.12constantat25℃byathermoscopeandaheater,andthewastewaterwasmixedbya7312-typestirrer.Aminitypeairpumpwasusedtosupplyoxygentothereactor.Stirrerandairpumpwereoperatedalternativelybyatimecontroller.1.3　SequencingbatchreactorsoperationsTable2　TheprocedureofSBR1andSBR2SBR1SBR2Fillingandmixing13Reaction66Mixing42Reaction62Setting22Withdrawing11Thereactorswereoperatedinasequencingbatchmodeinordertoimprovetheactivityofthesystem.ThebestprocedureofSBR1andSBR2wasaccordingasthecharacteristicsofthetwodifferentkindsofthewastewater(Table2).Thecyclelasted20hforbothSBR1andSBR2.Thevolumeoftheinfluentwastewaterwas2L.1.4　AnalyticalmethodsAmmonianitrogen(NH+4-N),nitritenitrogen(NO-2-N)andnitratenitrogen(N