Operational qarameters to keep high nitrification rate in activated sludge process under low temperature

Based on the five years operation of Chinese Daqing Chengfengzhuang Wastewater Treatment Plant, operational parameters to keep high nitrification rate at low water temperature were summarized. It was stated that, by keep high activated sludge concentration and low sludge loading(0.15kg(BOD 5)/(kg(MLSS)·d)), even when the wastewater temperature is 8—10℃, high nitrification rate (above 80%) and good organic removal can be reached.