英文英语文章-Comparative evaluation of mass transfer of oxygen

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1、ComparativeevaluationofmasstransferofoxygeninthreeactivatedsludgeprocessesoperatingunderuniformconditionsVenkatramMahendraker,DonaldS.Mavinic,andKennethJ.HallAbstract:Thisinvestigationwasconductedinthreelaboratory-scaleactivatedsludgeprocesses,namely,theconventionalcompletelymi

2、xedactivatedsludgeprocess(CMAS),themodifiedLudzack-Ettingerprocess(MLE),andtheUniversityofCapeTown(UCT)process.Thesesystemswereoperatedundercontrolledconditionsbyfeedingauniforminfluentatasingle10-dsolidsretentiontime(SRT).Theoxygentransferparameters(KLaf,OTRf,andOTEf)determine

3、dindicatedthatthealpha(α)andoxygentransferefficiency(OTEf)inprocesseswheretheenhancedbiologicalphosphorusremoval(EBPR)mechanismwasactivewerehigherthanintheconventionalcompletelymixedactivatedsludge(CMAS)process,wheresuchamechanismwasabsent.Thus,presentingaclearevidenceofimprove

4、doxygenutilizationinactivatedsludgeprocessescontainaerobic,anoxic,andanaerobicselectorzones.Keywords:biologicalnutrientremoval,completelymixedactivatedsludgeprocess,oxygenuptakerate,oxygentransferefficiencyMaterialandmethodsFig.1.Schemesfor(a)completelymixedactivatedsludge(CMAS

5、)process,(b)modifiedLudzackEttinger(MLE)processand(c)UniversityofCapeTown(UCT)process.TheCMAS,MLE,andUCTprocessschemesemployedinthisstudyareshowninFig.1.Intheseprocesses,theaerobic,anoxic,andanaerobicreactorvolumeswere16L,8.55L,and3.85L,respectively,whereas,theclarifiervolumew

6、asequalto5.25L.Thepercentageofanoxicreactorvolumewasequalto35％ofthetotalprocessvolume(excludingtheclarifier)intheMLEprocess,whereas,thepercentagesofanoxicandanaerobicvolumeswereequalto30％and13.5％(excludingtheclarifier),respectively,intheUCTprocess.Theinfluentandbiomassrecircula

7、tionflowrates(includingreturnactivatedsludge)wereconstantat3L/h,inallsystems.Eachofthereactorshadamixeroperatingat60rpmformixingthereactorcontents,andtheclarifierhadaninternalscraperrotatingat4rpmtodislodgetheattachedbiomass.Theentiresetupwaslocatedwithinatemperaturecontrolle

8、droomsetat20±0.5℃andthesystemswereoperatedata10dSRT.T