Aww plant has ww with 450 mg/l bod (the soluble bod is 250 mg/l) and 280 mg/l ss. the biological tower treatment process consists of high-density, cross-flow packing media with dimensions of 480 sq ft by 20 ft high. the packing has a specific area of 42 sq ft/cubic ft, n = 0.5 and k20 =0.0035 (gpm/sq ft)0.5. the primary clarifier effluent is 0.8 mgd at 18oc. the recirculation ration is 1.0. calculate the effluent soluble bod at 20oc, then correct the calculation for actual temperature. calculate the soluble and total effluent bod assuming that the effluent has 0.54 soluble bod/total bod.

Liquid flows at steady state at a rate of 2 lb/'s through a pump, which operates to raise the elevation of the liquid 100 ft from control volume inlet to exit. the liquid specific enthalpy at the inlet is 40.09 btu/lb and at the exit is 40.94 btub. the pump requires 3 btu/s of power to operate. if kinetic energy effects are negligible and gravitational acceleration is 32.174 tt/s, the heat transfer rate associated with this steady state process is most closely 1)-2,02 btu/s from the liquid to the surroundings 2)-3.98 btu/s from the surroundings to the liquid. 3)-4.96 btu/s from the surroundings to the liquid. 4)-1.04 btu/s from the liquid to the surroundings.