A wastewater treatment plant consists of primary treatment followed by an activated-sludge secondary system. The plant processes 7000 m3/d of wastewater with 180 mg/L of BOD5 and 150 mg/L of suspended solids. The primary sludge contains 500 kg of dry solids per day with 4.5% solids content. The plant produces 760 kg of total sludge (primary and secondary) per day. Assume 30% removal efficiency of the primary clarifier and F/M ratio of 0.2 for the aeration tank. Determine the following: a. Primary sludge volume and removal efficiency of primary clarifier
b. Influent and effluent BOD5 of the secondary activated-sludge system
c. Volume of secondary sludge with 1% solids content