A conventional nitrification-denitrification system consists of an anoxic basin and an aerobic basin. In an anoxic basin denitrification occurs, and nitrification occurs in an aerobic basin. However, the pilot plant of night soil treatment, using the10meter deep aeration tank, has demonstrated its ability to achieve simultaneous nitrification and denitrification under anoxic conditions. Denitrification of nitrified night soil was achieved with night soil organics with addition of methanol. The concentrations of BOD and T—N in final effluents were both less than 10mg/l without dilution. The results of the pilot-scale studies suggest that: (1) Oxygen transfer rate in the 10 m. deep aeration tank is in the 200 to 400 mg/l. h range. (2) Oxygen absorption efficiency is about 60% in the 10 meter deep aeration tank. (3) BOD removal in excess of 98% and T-N removal in excess of 90% are achieved in the 10 m. deep aeration tank at T-N sludge load of 0.067 to 0.093kg·T-N/kg.SS.day, BOD load of 2.0 to 3.4 kg.BOD/m3·day, and disolved oxygen concentrations of 0.5 to 1 mg/l.