a completely mixed activated sludge plant is to treat 10,000 m^3\day. the wastwater has a BOD5 of 1200 mg\liter that must be reduced to 200 mg\liter.if the mean cell residence time 5 days and suspended solids concentration of 5000 mg\liter and Y 0.7 kg\kg and kd 0.03 \day determine sludge recycle ratio R?