m Problem 3 A perfectly mixed flow activated-sludge plant is to treat 10,000 m3/d of industrial wastewater. The wastewater has a BOD5 of 1200 mg/L that must be reduced to 200 mg/L prior to discharge to a municipal sewer. Pilot-plant analysis indicates that a mean cell- residence time of 5 d maintaining MLVSS concentration of 5000 mg/L produces the desired results. The value of Y is determined to be 0.7 kg/kg and the value of kd is found to be 0.03 d-1. Determine (a) The volume of the reactor (b) The mass and volume of solids wasted each day at 12,000 mg/L (C) The sludge recirculation ratio