1. A conventional activated sludge plant without primary clarification operates under the following conditions: Design flow : 8100 m/d : 185 mg/L : 212 mg/L : 4 units, 12 m square x 4.5 m deep : 2600 mg/L Influent BOD Suspended Solids Aeration basins Mixed liquor Suspended solid : 3800 m/d : 150 m/d Recirculation flow Waste sludge quantity Suspended solids in waste sludge : 8600 mg/L : 15 mg/L : 15 mg/L Effluent BOD Suspended Solids Calculate: a) Aeration period b) BOD loading c) Return activated sludge (%) d) F/M ratio e) Suspended solids and BOD removal efficiencies f) Sludge age