A wastewater treatment plant discharges 1.0m3/s of effluent having an ultimate BOD of 40.0mg/L into a stream flowing at 10.0m3/s. Just upstream from the discharge point, the stream has an ultimate BOD of 3.0mg/L. The deoxygenation constant kd is estimated at 0.22/ day. (a) Assuming complete and instantaneous mixing, find the ultimate BOD of the mixture of waste and river just downstream from the outfall. (b) Assuming a constant cross-sectional area for the stream equal to 55m2, what uttimate BOD would you expect to find at a point 10,000m downstream