Question

Determine the area required for a FWS constructed wetland used to treat primary treated wastewater with an influent BOD of 120 mg/L. To be assured of odorless operation, the maximum organic loading rate is to be equal to or less that 100 lb BOD/ac.d. Assume the overall first-order BOD removal rate constant is 1.0 d-1 at 20°C. The average wastewater temperature during the coldest month is about 10°C. The average water depth is to be 1.25 ft. Because of evaporation, the effluent flowrate is equal to 0.7 ´ the influent flow rate. Assume that the plant porosity if 0.60 and that the average BOD in the effluent due to plant decay is 8 mg/L. The combined effluent BOD (from plant decay and residual from influent) must be 25 mg/L or less. The observed temperature coefficient and COR values for a similar FWS system in the same temperature regime are 1.02 and 0.50 (at 99 percent), respectively.

Answer 1