Nitrifying-Moving-Bed-Biofilm-Reactor-Biofilm-and-Biomass-Response-to-Long-Term-Exposure-to-1oC

MANUSCRIPTACCEPTEDACCEPTEDMANUSCRIPTGraphicalAbstractAirMorphology&ThicknessofMBBRCarriersMixingPatternViabilityofBiomassatdepth,Live(green)&Dead(red)MixingPatternMANUSCRIPTACCEPTEDACCEPTEDMANUSCRIPT1Title:NitrifyingMovingBedBiofilmReactor(MBBR)BiofilmandBiomass1ResponsetoLongTermExposureto1oC2V.Hoanga,R.Delatolla*a,T.Abujamelb,W.Mottaweab,A.Gadboisc,E.Laflammec,A.3Stintzib4aDepartmentofCivilEngineering,UniversityofOttawa,Ottawa,Ontario,K1N6N55bOttawaInstituteofSystemsBiology,DepartmentofBiochemistry,Microbiology,and6Immunology,UniversityofOttawa,Ontario,K1H8M57cJohnMeunierInc.,Montreal,Quebec,H4S2B38*Correspondingauthor:DepartmentofCivilEngineering,UniversityofOttawa,Ottawa,9ON,161LouisPasteur,K1N6N5;E-mail:robert.delatolla@uottawa.ca,Phone:613-562-105800ext.267711MANUSCRIPTACCEPTEDACCEPTEDMANUSCRIPT212ABSTRACT13Thisstudyaimstoinvestigatemovingbedbiofilmreactor(MBBR)nitrificationrates,14nitrifyingbiofilmmorphology,biomassviabilityaswellasbacterialcommunityshifts15duringlong-termexposureto1oC.Long-termexposureto1oCisthekeyoperational16conditionforpotentialammoniaremovalupgradeunitstonumerousnorthernregion17treatmentsystems.TheaveragelaboratoryMBBRammoniaremovalrateafterlong-term18exposureto1oCwasmeasuredtobe18±5.1%ascomparedtotheaverageremovalrate19at20oC.Biofilmmorphologyandspecificallythethicknessalongwithbiomassviability20atvariousdepthsinthebiofilmwereinvestigatedusingvariablepressureelectron21scanningmicroscope(VPSEM)imagingandconfocallaserscanningmicroscope22(CLSM)imagingincombinationwithviabilitylive/deadstaining.Thebiofilmthickness23alongwiththenumberofviablecellsshowedsignificantincreasesafterlong-term24exposureto1oC.Hence,thisstudyobservednitrifyingbacteriawithhigheractivitiesat25warmtemperaturesandaslightlygreaterquantityofnitrifyingbacteriawithlower26activitiesatcoldtemperaturesinnitrifyingMBBRbiofilms.UsingDNAsequencing27analysis,NitrosomonasandNitrosospira(ammoniaoxidizers)aswellasNitrospira28(nitriteoxidizer)wereidentifiedandnopopulationshiftwasobserv