寒冷天气下新型复合式生物生态系统省略艺处理生活污水的协同作用英文张鹏

ChineseJournalofChemicalEngineering,19(5)881—890(2011)SynergismofNovelSequenceBio-ecologicalProcessandBiologicalAeratedFilterforSewageTreatmentinColdClimate*ZHANGPeng(张鹏),HAIReti(海热提)**,ZHOUDongkai(周东凯),HEYiqun(何一群)andBAIZhiyuan(白志远)DepartmentofEnvironmentalScienceandTechnology,CollegeofChemicalEngineering,BeijingUniversityofChemicalTechnology,Beijing100029,ChinaAbstractAlab-scaleintegratedtreatmentsystemincludingthenovelsequencebio-ecologicalprocess(SBEP)andbiologicalaeratedfilter(BAF)forasewagemixture(chemistrylaboratorywastewateranddomesticsewage)waspresentedinthispaper.Themainobjectiveofthestudywastotestthecontributionofartificialaeration,recir-culationratioandmassconcentrationofsteelslagonpollutantremovalinwinterwhentheplantsaredormant.IthadbeenshownthatSBEPandBAFplaydifferentrolesinremovingcontaminantsfromwastewater.Duringtheairflowexperiment,theremovalefficiencyofCODandTPinSBEPwashigherthanthatinBAF,whereasBAFcancompensateforthedeficiencyofSBEPwherenosignificantimprovementonammoniumnitrogenremovalisob-served.Yet,theremovalefficienciesofCOD,TPand4NH+-NinSBEPcouldbeimprovedapparentlywhendiffer-entrecirculationratioorvariousmassconcentrationofsteelwereapplied.Especially,whentheairflowof0.06L·h−1,therecirculationratiorateof80%andthemassconcentrationofsteelof2.2-2.4g·L−1wereapplied,thehighestefficiencyof94.6%,77.9%and80.7%forCOD,TPand4NH+-Nwereachieved,respectively.Theinte-gratedtreatmentsystemofSBEPandBAFwasprovedtobeaneffectivewastewatertreatmenttechniqueandabet-teralternativetotreatdomesticsewage.Keywordsverticalsubsurfaceconstructedwetlands,biologicalaeratedfilter,bio-contactoxidationprocesscar-bonfiber,aeration,recirculationratio1INTRODUCTIONConstructedwetlands(CWs)areanecologicallyengineeredsystemandakintonaturalwetlands(NWs),andhasbeenrecognizedasacost-effectiveapproachtoremovethebiologicaloxygendemand(BOD),totalsuspendedsolids(TSS),bacteria(Escherichiacoli,totalcoliforms),nitrogen(N)andmetalsfromdiffer-entkindsofwastewaters[1-7].Incurrentresearches,althoughCWshavebeenappliedwidelyinUSA,Finland,Italy,NewZealand,BelgiumandPolandasasuccessfultechnology[8-17],therearesomeproblemsneedtobeimproved.InCWs,thebiologicalprocessesaretemperaturedependant,andtheremovalperformancesofbothni-trogenandsolubleorganicmatterarehighlydrivenbybiologicalactivity.Inaddition,althoughoxygensolu-bilityishigherincolderwater[18],gasexchangemaybereducedbytheadditionalinsulationlayerwhenplantsaredormant.Therefore,inwinter,CWsshowalittlepurificationefficiency[19].Consideringthecouplednitrification-denitrificationprocessinCWs,generally,totalnitrogen(TN)canberemovedefficientlyasitcanbeconvertedtogaseousnitrogenandbeemitted.However,tobetterremoveTPinCWs,thereisanextraneedtoharvestplantsandremovethesaturatedfiltermedia.Inmanypreviousstudies,ithasbeenprovidedthattheapplicationofvariousmediaincludinglimestone,shale,slag,gravel,flyash,blastfurnaceslag,lightexpandedclayaggre-gates(LECA)andotherartificialmaterialsinCWshasmadeitsTPremovalreachto98%-100%[20-23].However,thevastamountofprecipitationwrappingonthefiltermediainCWswillhamperthereleasingprocessofCa2+andFe3+,andcauseloweradsorptionefficiencyofthefiltermedia.Ontheotherhand,oncethematerialissaturatedinCWs,itwillhavetobeeitherwashedor,moreprobably,replaced,orelse,whichwillresultincloggedwetlandsiffailuretodoanythingatall.Therefore,itisdifficulttoremoveTPthoroughly.InCWs,cloggingmaybecausedbydepositionoforganicandinorganicsolids,whichdevelopsabiologicalmat,leadingtoanouterblockageofsoilpores[24].Cloggedwetlandscancreatepreferentialflowpatterns,short-circuitingandodors[25].There-fore,failureofwetlandtreatmentsystemoftenoccurswhenthewetlandiscloggedandpreferentialflowpathsarecreated[25,26].Asanotherwastewatertreatmenttechnology,biologicalaeratedfilters(BAFs)isanovel,flexibleandeffectivebioreactorthatprovidesasmallfootprintprocessatvariousstagesofwastewatertreatment[27].Withhighamountofactivebiomassandvarietyofmicrobialpopulationsinpackingmedia,BAFsisin-troducedasapowerfulsystemtotreatthestreamwithhighorganiccontent.However,BAFsisdifficulttotreattherawwastewatercontaininghighconcentrationofsuspendedsolid(SS).Ontheotherhand,inordertoremovetheaccumulatedSSandtheexcessbiomassthoroughly,BAFsmustbebackwashedmorefre-quentlythroughacounter-currentmanner,andinthisReceived2011-01-10,accepted2011-08-20.*SupportedbytheImportantNationalScience&TechnologySpecificProjects(2009ZX07526-005-05).**Towhomcorrespondenceshouldbeaddressed.E-mail:[e-mail].,Vol.19,No.5,October2011882way,moreenergyinputandadditionalcostarerequired.Accordingly,inthispaper,weintroducedanin-tegratedtreatmenttechnologyofthenovelsequencebio-ecologicalprocess(SBEP)andbiologicalaeratedfilter(BAF),whichcanimprovetheremovaleffi-ciencyofammoniumnitrogenandTP,avoidwetlandclogging,anddecreaseenergyconsumptionunderahighhydraulicload.Theaimofthisstudyistoevalu-atetheremovalofchemicaloxygendemand(COD),ammonianitrogen(4NH+-N)andTPinalab-scaleSBEP-BAFfortreatmentofdomesticsewageusingdifferentconcentrationofairflow,recirculatio