Pilot Plant Studies of Oxygen Utilization, Sludge Production and Respiration Heat in Nitrogen Removal of Night Soil Using The U-tube Bioreactor with a Membrane Filter.

Oxygen utilization, respiration heat and sludge production in biological nitrification and denitrification of night soil were studied in the pilot and full-scale plants using a U-tube bioreactor with a membrane filter for separation of activated sludge from purified night soil. The U-tube bioreactors were operated under conditions of high MLSS (21kg·m-3) and high aerobic SRT (29days). Heterotrophic respiration rates and heat in the bioreactor were measured. The experimental equations for prediction of oxygen utilization and heat production rate for nitrification and denitrification of night soil was proposed and verified by using our full-scale plants. It was found that the growth rate of microorganisms was approximately equal to the decay rate of microorganisms under the operating conditions of high aerobic SRT and the amount of excess sludge was approximately equal to the content of non-oxidizable solids in night soil pretreated by a centrifuge.