上升流速对CANON工艺稳定性及微生物群落的影响

上升流速对CANON响CNNCNN系统中的亚硝化反应器和反硝化反应器的氨氧化和硝化效率及总氮去除效率均有显著的影响。此外，上升流速CNN系统中微生物群落的结构和序列，导致微生物间竞争、CNN系统的优化和稳定化过程中，应考虑上升流速的影响。CANON(CompletelyAutotrophicNitrogenRemovalOverNitrite)technology,whichcombinestheanammoxandthenitriteoxidizingbacteria,hasattractedwidespreadattentionduetoitsadvantagesoflowenergyconsumptionandhighefficiencyinnitrogenremoval.ThekeytothesuccessofCANONtechnologyistocreateastableandbalancedmicrobialcommunityinthereactor.However,theinfluenceofhydrodynamicconditionsontheCANONsystemhasnotreceivedenoughattention.Theupflowvelocityisoneofthemostimportantfactorsaffectingthehydrodynamicconditionsinthereactor.Ithasbeenreportedthatupflowvelocityaffectsmicrobialcommunitystructureandoxygentransferefficiency(Wangetal.,2016;Zhangetal.,2019).However,fewstudieshavefocusedontheinfluenceofupflowvelocityonthestabilityoftheCANONprocessandthemicrobialcommunitystructure.Therefore,thisstudyaimedtoinvestigatetheeffectsofupflowvelocityonthestabilityofCANONprocessandthemicrobialcommunitystructure,providinginsightsforoptimizingandstabilizingCANONMaterialsandmethodsExperimentalsetupTheCANONreactorwasacolumnwithaninnerdiameterof14cmandaheightof120cm,madeoftransparentacrylic.Thereactorwasfilledwithpolyethylenecylinderswithadiameterof1cmandaheightof1.5cm.Thetotalpackedbedvolumewas26L.Theinfluentnitrogenconcentrationwas200mg/L,andtheinfluentorganicmatterconcentrationwasbelow50mg/L.Thesystemwasoperatedataconstanttemperatureof30±1°C,andthepHwasmaintainedat7.5±ExperimentalTheupflowvelocitiesof2,4,6,and8m/hwereappliedtofourindependentcolumns.Thestableoperationofthereactorwasconfirmedbymaintainingthetotalnitrogenremovalefficiencyabove60%foratleast30days.Watersampleswerecollectedtwiceaweekfromtheinfluent,effluent,andintermediatepositions.Theinfluentandeffluentnitrate,nitrite,andammoniumconcentrationsweremeasuredusinganionchromatographysystem(DIONEXICS-900).MicrobialcommunityThemicrobialcommunitystructurewasanalyzedbyhigh-throughputsequencingofthe16SrRNAgene.Thesampleswerecollectedfromindependentcolumnsonday60whenthereactorhadstabilizedunderdifferentupflowvelocities.ThesequencingdatawereanalyzedwiththesoftwareQIIME2.0andRsoftware.ResultsandEffectofupflowvelocityonCANONAsshowninFigure1,theupflowvelocityhadasignificanteffectontheammoniaoxidationrate,nitriteoxidationrate,andtotalnitrogenremovalefficiencyoftheCANONsystem.Withtheincreaseofupflowvelocity,theammoniaoxidationratedecreasedsignificantly,whilethenitriteoxidationrateincreasedsignificantly.Whentheupflowvelocitywas2m/h,thenitrateandnitriteconcentrationswereverylow,indicatingthatthenitrificationprocesswasinhibited.Whentheupflowvelocitywas8m/h,thenitrateconcentrationwashigh,indicatingthatthedenitrificationprocesswasnotsufficient.Thetotalnitrogenremovalefficiencydecreasedgraduallywiththeincreaseofupflowvelocity,andtheoptimalupflowvelocitywas4m/h.EffectofupflowvelocityonmicrobialcommunityThemicrobialcommunitystructurewasanalyzedatthephylumandgenuslevels.AsshowninFigure2(a),theupflowvelocityhadsignificanteffectontherelativeabundanceofdifferentphyla.Whentheupflowvelocitywas2m/h,therelativeabundancesofProteobacteria,Nitrospirae,andWD272werehigherthanthoseunderotherupflowvelocities.Whentheupflowvelocitywas8m/h,therelativeabundanceofPlanctomyceteswashigherthanthatunderotherupflowvelocities.AsshowninFigure2(b),theupflowvelocityhadasignificanteffectontherelativeabundanceofdifferentgenera.TherelativeabundancesofNitrosomonas,Nitrosospira,Candidatus_Kuenenia,andNitrospirawerehigheratlowerupflowvelocities.TherelativeabundancesofPlanctomyces,Phycisphaera,andPseudomonaswerehigherathigherupflowvelocities.ThisstudyinvestigatedtheeffectsofupflowvelocityonthestabilityoftheCANONprocessandthemicrobialcommunitystructure.Theresultsindicatedthatupflowvelocityhadasignificanteffectontheammoniaoxidationrate,nitriteoxidationrate,andtotalnitrogenremovalefficiencyoftheCANONsystem.Theoptimalupflowvelocitywas4m/h.TheupflowvelocityalsoaffectedtherelativeabundanceofdifferentphylaandgenerainthemicrobialcommunityoftheCANONsystem,suggestingthatupflowvelocityaffectedthecompetition,cooperation,andsymbiosisrelationshipsamongmicroorganisms.ThesefindingsprovideinsightsforoptimizingandstabilizingCANONThisstudywasfinanciallysupportedbytheNationalNaturalScienceFoundationofChina(No.31972754)andtheShanghaiMunicipalScienceandTechnologyMajorProject(No.2017SHZDZX01).Wang,S.,Peng,Y.,&Wang,S.(2016).Effectsofupflowvelocityonnitrification,denitrification,andcombinationofthetwoinanairliftinternalcirculationmembranereactor