This is a sample problem to prepare for an exam, not for any points, just for preparation. We weren't given the solution, and I want to be sure to get the most points for it. Please help if you can.
An activated sludge aeration tank has a width of 14m, a length of 15m and an effective liquid depth of 4.5m. The secondary clarifier has a diameter of 25m. The plant operating parameters are as follows.
Flow = 0.15 m^3/s, soluble BOD_5, after primary settling = 150 mg/L, MLVSS = 2,500 mg/L, MLSS = 1.4 (MLVSS), settled sludge volume after 30 min = 490 mL/L, wastewater temperature = 20°C, yield coefficient = 0.50, decau constant = 0.05 d^-1, effluent soluble BOD_5 = 10.0 mg/L,
a) Determine the aeration period, F/M ratio, solids concentration in the return sludge, return sludge rate, sludge age, and sludge wastage flow rate.
b) Determine the overflow rate, solids loading, weir loading, and side water depth of the secondary clarifier.