A completely mixed activated-sludge process is being designed for a wastewater flow of 10,000 m3/d (2.64 mgd) using the kinetics equations. The influent BOD5 of 180 mg/l is essentially all soluble, and the design effluent BOD5 is 20 mg/L. The effluent biosolids concentration is 15 mg/l, of which 80% is volatile and 65% is biodegradable. For sizing the aeration tank, the SRT is selected to be 8 d and the MLVSS 3000 mg/L. The kinetic constants are as follows:
Y=0.6 mg VSS/mg BOD, ka = 0.06 d-1, Ks = 60 mg/L of BOD, and k = 5.0 day-1.
Determine the efficiency of soluble BOD removal, using the formula
E=S0-Se/S0 X 100
Here, S0 is influent soluble BOD concentration and Se is influent soluble BOD concentration.