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环境工程专业外文翻译啤酒废水处理
英文原文
Sludgereductionduringbrewerywastewatertreatmentbyhydrolyzation-foodchainreactorsystem
Abstract:
Duringbrewerywastewatertreatmentbyahydrolyzation-foodchainreactor(FCR)system,sludgewasrecycledtotheanaerobicsegment.Withthefunctionofhydrolyzationacidificationintheanaerobicsegmentandtheprocessesofaerobicoxidationandantagonism,predation,interactionandsymbiosisamongmicrobesinmultileveloxidationsegment,residualsludgecouldbereducedeffectively.The6-monthdynamicexperimentsshowthattheaveragechemicaloxygendemand(COD)removalratiowas92.6%andaveragesludgeproductionoftheaerobicsegmentwas8.14%,withtheCODoftheinfluentat960–1720mg/Landhydraulicretentiontime(HRT)of12h.Sincetheproducedsludgecouldberecycledandhydrolyzedintheanaerobicsegment,noexcesssludgewasproducedduringthesteadyrunningforthissystem.
Keywordshydrolyzation,multileveloxidation,excesssludge,reduction
1.Introduction
Duringthe1980s,themainbrewerywastewatertreatmentlocallyandabroadwastheaerobictechnique,thenthehydrolytic-aerobictechniquesshowedupinthelate1980s.Currently,themaintechnologyforbrewerywastewatertreatmentaretheactivatedsludgeprocess,contactoxidationprocess,andhydrolytic-aerobictechniques.Althoughthesetechniqueshavesomeadvantagesoftheirown,theyallhaveaproblemwithsludgedisposal[1].Thesludgeproductionisabout60%ofthechemicaloxygen
demand(COD)removalamountforconventionalactivatedsludgetechnology,andabout30%forconventionalbiofilmmethod[2].Thecostofsludgedisposalhadbecomeaneconomicburdenofthesewageplant.Thesludgeproducedmaybringaboutsecondarypollution.Therefore,thestudyonwatertreatmentprocessesthatcanleadtosludgereductionisbecomingoneoftheimportantissuesinsewagetreatment.
Thisstudyadoptedprinciplesofcleanerproduction.Withthehydrolyzation-acidificationinanaerobicsegments,residualsludgecouldbetranslatedintosolubleorganicmatterandsmallorganicmolecules,thenentertheaerobicsegmentasorganicload.Aseriescontactoxidationsystemforfoodchainreactor(FCR)wasappliedintheaerobicsegmenttoformamanualbiogeocenoseandfoodchain.Basedonbiologicaltheory,thelongerthefoodchainis,themoreenergylost,andthuslessenergythatcanbeusedforgrowthoftheorganisms,andlessbiomassleftintheecosystemasaresult.Therefore,prolongingthefoodchainandstrengtheningthepredationofmicrozoansinthefoodchainarebotheffectiveinsludgereduction.‘‘ZeroDischarge’’ofresidualsludgewasachievedduringthebrewerywastewatertreatmentbyahydrolyzation-FCRsystem.Thisstudyexploredthemechanismofsludgereductionduringthehydrolyzationprocessandmultileveloxidationprocess。
2Materialandmethods
2.1Characteristicsofwastewater
Theexperimentalwaterisaman-madesimulantbrewerywastewater,whichcontainsbottledbeer,NH4Cl,KH2PO4,MgSO4,andCaCl2.Thebiodegradabilityindex,theratioofconcentrationsofbiochemicaloxygendemandfor5days(BOD5)andCOD,isabout0.4–0.5.Table1showsthemainwaterqualityproperties.
2.2Experimentalapparatusandexperimentalflow
Theexperimentalapparatuswasahybridbiologicalreactor(ShanghaiBestEnvironmentalTechnologyCorporation,Shanghai,China)asshowninFig.1.TheaerobicsectofFCRwasdividedintofourpartsalongthetreatmentprocessandtheirefficientvolumeswerew0.12,0.09,0.09,and0.06m3,respectively(theateris0.97mdeep).Sewagewaspouredintothereactor,thenflowedintoeachtank,withthefunctionofgravitationalactionandarotameteradjustingtheflow.Volumetricratioofthehydrolyzationsegmentandmultileveloxidationsegmentwas0.8:
1.Sewagewastreatedduringthehydrolyzationsegmentandalltanksofthemultileveloxidationsegment,thenflowedintoasedimentationtankwheresludgeandwaterwereseparated.Theexcessivesludgewasdischargedregularly,andrecycledintothehydrolyzation-acidificationsegment.Atthebottomofthemultileveloxidationsegmentwasanaerationdevice.
Fig.1Diagramoftheexperimentaldevice
1.high-positionedflume,2.volume-constantflume,3.hydrolyzationtank,4.multileveloxidationFCRsystem,5.fillers,6.baffle,7.entering-waterpipeforsedimentationtank,8.sedimentationtank,9.outletpipe,10.dischargepipe,11.aerationdevice,12.rotameter,13.ride,14.aerationdiffuse
2.3Operationparameters
Duringthetwo-monthexperimentalduration,theroomtemperaturewasintherangeof14–27uC.Thetotalhydraulicretentiontime(HRT)ofthissystemwas12h,andtheHRTofthehydrolyzationsegmentwas5.5h.
Concentrationsofdissolvedoxygenwere2–6mg/L.
2.4Analysismethods
Theindicatorsofsourcewaterweremeasuredaccordingtomonitoringandanalyticalmethodsofwaterandwastewater[3].
3Experimentalresultsanddiscussion
3.1RemovaleffectofCOD
Figure2showstheCODremovaleffectofthehydrolyzation-FCRsystemduringthesteadyrunningtimeperiodWhentheconcentrationsofCODintheinfluentwere960–1720mg/L,andHRTwas12h,theremovalratio
ofCODwasabove90%,andtheconcentrationofCODintheeffluentwas45–95mg/L.ThewaterqualityoftheeffluentmetthefirstclassoftheIntegratedWastewaterDischargeStandard[4].
Fig.2CODremovalefficiencyduringthecontinuousrunningtimeperiod
3.2Sludgeremovaleffect
Sludgeproducedbythissystemwasrecycledtothehydrolyzationsegmentwhereitwashydrolyzedandtranslatedintoorganicloadandpouredintothemultileveloxidationsegment.Thispartoftheorganicmatterwasmostlyreleasedasenergyexceptforarelativelysmallportion
translatedintoorganism.Inarealoperation,theremightbenegativegrowthofsludgeinthehydrolyzationsegmentsincethemicrobeofwhichneedslotsofenergyaswell.Asaresult,therecycledsludgecouldbeasupplyforthehydrolyzationsegment.Theoretically,‘‘ZeroDischarge’’
ofresidualsludgecouldbeachievedandtheexperimentalresultshaveverifiedthispoint.
ThesludgeproductionoftheFCRsystemwascontinuouslyinvestigatedduringthetwo-monthsteadyrunningperiod,andtherelationshipbetweentotalsludgeproductionandtotalCODremovalamountwasanalyzed.Figure3showsthattheratioofsludgeproductionwas6%–10%,andtheaveragesludgeproductionwas8.15%,whichisabout15%ofconventionalactivatedsludgetechnologyand25%ofconventionalbiofilmmethod.TheresultsshowthattheFCRsystemhasgreateffectonsludgereduction.
Fig.3Sludgeproductionofthemultileveloxidationsegmentduringthesteadyrunningtimeperiod
4Mechanismanalysis
ThebiologicalfunctionofthecarrierandtherunningmodeofmultileveloxidationFCRmadetheconcentrationofthesewagegradientalonewithcurrent,whichformedthreedifferentzonesinthetank:
polysaprobic,mesosaprobic,andoligosaprobiczones.Eachzonehasadifferentmicroorganismcommunity(fromthebasictoadvanced),whichformedarelativelyintegratedecologicalstructureandafoodchainasbacteria-protozoa-metazoa-daphnia.BytheanalysisoftheFCRsystem,muchmoremicrobesindifferentkindsandqualitywerefoundthantheconventionalaerobicprocess.Asaresult,thefoodchaininthissystemwasmorecomplicatedthanotherprocesses.Figure4showsthecompositionsofthefoodchainoftheFCRsystem.Basedonbiologicaltheory,thefoodchainisgettinglongerandmorecomplex,therelationshipbetweenmicrobesinthefoodchainismorecomplex.Throughtheprocessofantagonist,predation,interactionandsymbiosis
amongmicrobes,themicrobesystemisbalanced,andnoneofthespecificpopulationcouldover-develop[8,9].Highertrophicdegreeofthepredator,moreenergyconsumed,andlessenergythatcanbeusedforthegrowthoforganisms[10–12].Withtheeffectofallthesefactors,theecosystemcouldmaintainarelativelystableterm.Asaresult,lesssludgewouldbeproducedinpractice.
Fig.4CompositionsofthefoodchainoftheFCRsystem
5Conclusions
(1)WhentheconcentrationsofCODintheinfluentwere1200–1800mg/L,HRTwas12h,andaverageCODremovalratiowas92.6%.‘‘ZeroDischarge’’ofresidualsludgewasachievedduringthesteadytimerunningforthissystem,sincetheproducedsludgecouldberecycledandhydrolyzedtotheanaerobicsegment.Withoutsludgedisposalequipmentadded,thismethodcouldhavebotheconomicandenvironmentalprofitinpractice.
(2)TheprocessofmultileveloxidationFCRcouldformamicrobeecosystemjustlikethenaturalmicrobeecosystem,andafullydevelopedfoodchain.Throughtheprocessesofantagonism,predation,interaction,andsymbiosisamongmicrobes,sludgewaseffectivelyreduced.DuringthesteadyrunningofmultileveloxidationFCR,theaveragesludgeproductionoftheFCRsystemwas8.15%.
1DepartmentofEnvironmentalEngineering,UniversityofScienceandTechnologyBeijing,Beijing100083,China
2DepartmentofEnvironmentalScience&Engineering,HarbinInstituteofTechnology,Harbin150090,China
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