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Calculation of the Common Characteristics of a Complete-Mix Activated-Sludge System with Recycle

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Calculation of the Common Characteristics of a Complete-Mix Activated-Sludge System with Recycle

This online calculator gives an impression of some common characteristics for modelling a simple suspended growth process. The process will take place after a primary sedimentation and follows two stages: it will pass an aeration tank and a clarifier. Commonly some settled sludge from the clarifier will returned into the aeration tank to keep the process activated. To help you picturing it, you could visit the page with more information about the Activated-Sludge Process.

To use this calculator please fill in the input value data of your sewer wastewater and as a result some basic plant design and effluent BOD data will follow out of the calculations. If the normal sewer water characteristics are unknown, please press the "typical data" button for an auto fill of the input fields.
Under Related Calculators in the menu besides, you can find separated calculations of the results computed on this page. On the pages of these related calculations, there's some theory about the calculation.

Hover your cursor over the descriptions of the Kinetic Coefficients or Characteristics of Complete-Mix Suspended Growth Process and click on the link for more information.

Characteristics of Primary Sedimentation Effluent
wastewater flowrate Q = m3/d
influent soluble substrate concentration (bsCOD) S0 = BOD or bsCOD g/m3
nbVSS concentration in influent X0,i = g/m3 or mg/l
inert inorganics Total Suspended Solids (iTSS) iTSS = g/m3
total MLVSS concentration XT = g/m3 or mg/l
Sedimentation Retention Time (SRT) SRT = d
Kinetic Coefficients
maximum rate of soluble substrate utilization k = g COD/g·d
biomass yield Y = g VSS/g COD used
endogenous decay coefficient kd = g VSS/g VSS·d
half-velocity constant Ks = g COD/m3
fraction of biomass that remains as cell debris fd = g VSS/g VSS
biomass fraction VSS/TSS =
Characteristics of Complete-Mix Suspended Growth Process
effluent soluble substrate concentration (bsCOD) S = g bsCOD/m3
Hydraulic Retention Time (HRT) t = d
daily sludge production PX,T,VSS = kg VSS/d
PX,T,TSS = kg TSS/d
fraction of biomass in the MLVSS X/XT = kg/d
observed solids yield removed Yobs,VSS = g VSS/g bsCOD
Yobs,TSS = g TSS/g bsCOD
oxygen requirement R0 = kg/d

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