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)