A municipal activated sludge wastewater treatment plant with primary clarification and anaerobic digestion has the follo

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A municipal activated sludge wastewater treatment plant with
primary clarification and anaerobic digestion has the following
influent characteristics:
Flow=20,000m^3/d
BOD5=200mg/L @ 20 degree C
Suspended Solids = 200mg/L
The following data apply:
waste sludge flow rate= 400m^3/d
mixed liquor suspended solids = 2500mg/L
return sludge concentration = 6000mg/L
waste activated sludge concentration = 6000mg/L
aeration basin hydraulic residence time = 10 hr
Primary clarifier overflow rate = 900gal/d-ft ^2
a) if the plant’s BOD5 removal efficiency is 95% and the primary
clarifier removes 35% of the influent BOD5, the amount of BOD5
removed (kg/d) in the aeration tank is most nearly?
b) Calculate the aeration basin volume (m^3)?
c) Calculate Food to microorganisms ration (1/d)?
d) what is the mean cell residence time (days)?
e) if the MLSS is reduced to 1500mg/L, what is the mean cell
residence time (days)?
f) what is the organic loading rate (kg/m^3/d)?