title: Simultaneous nitrification/denitrification and stable sludge/water separation achieved in a conventional activated sludge process with severe filamentous bulking.
abstract: This study investigated the long-term treatment performance of a conventional activated sludge (AS) process operating at a microaerobic DO level (0.5-1.0mg·L-1) in the aeration tank and a long settling time of >10h in the clarification tank for sewage treatment. The microaerobic DO conditions led to severe sludge bulking. However, good sludge/water separation and excellent pollutant removal performance (COD, 95±2%; NH4+-N, 99±1%; and TN, 69±6%) were stably achieved in the microaerobic AS system during its 150days of continuous operation. This is the first report to demonstrate that a long settling time effectively overcame the effect of severe filamentous bulking in conventional AS process, and that microaerobic DO conditions achieved excellent simultaneous nitrification and denitrification reactions in the aeration tank. The process characteristics of the microaerobic AS system differed substantially from those existing biological denitrification processes, including A/O, CANON, and OLAND processes.
authors.affiliation: School of Environment, MOE Key Laboratory of Water and Sediment Sciences/State Key Lab of Water Environment Simulation, Beijing Normal University, Beijing 100875, China.
authors.forename: Xueyu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: School of Environment, MOE Key Laboratory of Water and Sediment Sciences/State Key Lab of Water Environment Simulation, Beijing Normal University, Beijing 100875, China. Electronic address: zsk@bnu.edu.cn.
authors.forename: Shaokui
authors.initials: S
authors.lastname: Zheng
authors.affiliation: School of Environment, MOE Key Laboratory of Water and Sediment Sciences/State Key Lab of Water Environment Simulation, Beijing Normal University, Beijing 100875, China.
authors.forename: Xuze
authors.initials: X
authors.lastname: Xiao
authors.affiliation: School of Environment, MOE Key Laboratory of Water and Sediment Sciences/State Key Lab of Water Environment Simulation, Beijing Normal University, Beijing 100875, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.affiliation: School of Environment, MOE Key Laboratory of Water and Sediment Sciences/State Key Lab of Water Environment Simulation, Beijing Normal University, Beijing 100875, China.
authors.forename: Yunjun
authors.initials: Y
authors.lastname: Yin
mesh_terms: D001420:Bacteria, Aerobic / Q000378:metabolism; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors; D058440:Denitrification; D058465:Nitrification; D009584:Nitrogen / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods*; D014867:Water; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification / Q000379:methods*
chemical_list: D009930:Organic Chemicals; D012722:Sewage; D014874:Water Pollutants, Chemical; D014867:Water; D009584:Nitrogen
keywords: Activated sludge process; Filamentous bulking; Microaerobic; Settling time; Simultaneous nitrification-denitrification