1. A complete mixed activated sludge process is operated with a clarifier and sludge recycle. The influent soluble BOD concentration is 300 mg/L and the flow is 1000 m3/day. The effluent soluble BOD is 20 mg/L and the effluent VSS concentration is 30 mg/L. What is the oxygen consumption rate of the aeration tank in kg/day? The sludge parameters are as follows: Um = 3 dl. Ks = 20 mg/L, ka = 0.1d"!, Y = 0.45 g VSS/g BOD