活性污泥模型Activated Sludge Models.pdf

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1、4-ActivatedSludgeModels_F11.docBacterialGrowthKineticsµmµµm/2KsSrdth(3:DC350;4DC459Fig.6-18)MonodgrowthrateconstantasafunctionoflimitingfoodconcentrationTheMonodModel:µSmµ=(1)K+Ss-1whereµ=specificgrowthrate,d-1µm=maximumspecificgrowthrate,dS=ratelimitingsubs

2、trate(food)concentration,mg/LKs=half-saturationcoefficient,mg/L=MonodConstant=half-velocityconstantµSmµ==KS'ifS<>Ks(1b)mS14-ActivatedSludgeModels_F11.docdXBacterialgrowthrater,gdtgdXµmSr==µX=X(2)gdtKsS+gwhere

3、X=bacteriaconcentration(inVSS),mg/LdSSubstrateUtilizationRate,r,sudtudXdS∞−dtgdtudXdS=−Y(3)dtgdtuwhereY=bacterialcellyield=yieldcoefficient,mgVSS/mgBODdXBacterialDeathRate,r,ddtddXr==kX(4)dddtd-1wherekd=deathratecons

4、tant=endogenousdecaycoefficient,dEndogenousphase-nearstarvationphaseNetGrowthRate=GrowthRate-DeathRatenet'dXdXdXr==−(5)gdtgdtgdtdwheredXdX=µX,=kXddtgdtdnet'dXr==(µ−kX)=µX(6)gdnetdtg24-ActivatedSludgeModels_F11.docµSYkSmµ=−

5、k=−k(7)netddK+SK+Sss-1wherek=maximumrateofsubstrateutilizationperunitmassofbiomass,dk=µm/Ynet'dXYkSr==µX=−kX(8)gnetddtK+SgsSubstrateUtilizationRate,rsudS1dX1µSmr===X(9)sudtYdtYK+SugsSincek=µm/Y,dSkSX=(10)dtK+SusAlso,inarea

6、ctordSSoS−=(11)dtuθSpecificSubstrateUtilizationRate,UdSdtudSU=or=UX(3)XdtudSdtSo−SSoSo(−S)QSoSo(−S)uU====XθXSoθXVXSoQSoSoS−FU==E(12)VXSoMwhereE=(So-S)/So=substrateremovalefficiencyθ=V/Q=hydraulicretentiontime=aeratio

7、ntime,hrF/M=Foodtomicroorganismsratio34-ActivatedSludgeModels_F11.docCombining(10)and(11)givesdSSoS−kSX==(13)dtθK+SusDividingEq.(13)byXyieldsdSdtSoS−kSu===U(14)XθXK+SskSU=(15)K+SsFrom(7)µSYkSmµ=−k=−knetddK+SK+Sssµ=YU−knetdCompletelyMixedActivated

8、SludgeProcessAssumptionsfortheformulationofthemassbalanceequations-Thefollowingconditionsareassumedintheformulationofthemassbalanceequations:(1)Steadystate-Flow,biomassconcentrations,andsubstrat