The 3rd problem requires the reference of problem 2 so problem 2 is given above

2. In the secondary treatment unit of a WWTP, two activated sludge aeration tanks are operated in series. Each tank has the following dimensions: 7.0 m wide by 30.0 m long by 4.3 m effective liquid depth. The plant operating parameters are as follows: Flow = 0.0796 m/s Soluble BOD5 after primary settling = 130 mg/L = MLVSS = 1,500 mg/L MLSS = 1.40 x (MLVSS) Settled sludge volume after 30 min = 230.0 mL/L Determine the following: (a) BOD loading (kg/d), (b) F/M ratio, (c) SVI, (d) aeration period (HRT) 3. Using the following assumptions, determine the solids retention time, the cell wastage flow rate, and the return sludge flow rate for the WWTP in Problem 2. Assume: Allowable BOD in effluent = 25.0 mg/L Suspended solids in effluent = 25.0 mg/L (30% of SS account for BOD) Yield coefficient (Y) = 0.60 mg VSS/mg BOD5 removed Decay rate of microorganisms (ka) = 0.060 d-l