7/30/2019 F-M Ratio - Activated Sludge
2/2
FLORIDAWATERRESOURCESJOURNAL MARCH199921
Equation3,is2500x8.34x0.25=5210lb.TheF/Mratioisthen992/5210=0.19,which
isbelowthestandardrangeof0.25to0.50.Theprocesshastoomuchsludge(weightofmicro-organisms)underaerationforthefoodbeingprovided.TheoperatorshouldwastesludgetolowertheMLTSSinaeration.DeterminingOptimalMLTSSTheoptimalMLTSSisbasedontheratio-
proportionformula,R1:R2::P1:P2,wheretheproductofthemeansisequaltotheproduct,or:
(R1xP2)=(R2xP1) (Equation4)whereR1 =thedesiredF/Mratio
=0.25fortheaboveexample.R2 =theMLTSScorrespondingto
thedesiredF/Mratio,or1.0pounds for an F/M ratio of0.25.
P2 =optimalMLTSSP1 =weightoffoodinaerationfrom
Equation3,or992lb/day intheaboveexample.
Therefore,fortheexampleplant:(0.25xP2)=(1.0x992)or,P2=(1.0x992)/0.25=3968lbsMLTSS.TheoptimalaerationMLTSSconcentration
canbefoundbyrewritingEquation3as:ppm=(poundsperdayMLTSS)/(8.34xMG)ppm=(3968lb/day)/(8.34x0.25MG)=1900.Therefore,1900ppmisthemaximumcon-
centrationofMLTSStoachieveaF/Mratioof0.25.
AnumberofyearsagowhenIwasayoungbuckinthewaterandwastewaterindustry,Iwrotesomearticlesonactivatedsludgeopera-tionfortheOverflowMagazine.Iamnowanold-timer,
but I still see a need for
someemphasisonunderstandingactivatedsludgeprocessoperation.
January WaterTreatment:Membranes.FSAWWAOfficers.
FebruaryWaterDistribution.FWPCOAOfficers
March WastewaterCollection.April
AnnualConferenceIssue.Misc.technicalarticles.
May WaterTreatmentJune FSAWWA&FWEAAwards.
Miscellaneoustechnicalarticles.July Disinfection.
August Conservation.
September IndustrialWastewater/ResidualsManagement.
October
WaterResourcesManagement/FWPCOAAwards.FSAWWAConference.
November Reuse.December WastewaterTreatment.FWEA
Officers.
EditorialCalendar
