title: Floatation of granular sludge and its mechanism: a key approach for high-rate denitrifying reactor.
abstract: A high-rate denitrifying automatic circulate (DAC) reactor has been developed recently, and it is promising to become an alternative in nitrogen removal from wastewaters. However, the performance of DAC reactor was disturbed by the floatation of granular sludge at high-loads. The results showed that: the floatation of granular sludge led to a serious biomass washout and a sharp decrease of biomass concentration. The floatation of granular sludge was ascribed to a low sludge density originated from the holdup of gaseous products. The average density and average gas holdup ratio of floated granular sludge were 913 kg m(-3) and 11.8% (by volume), respectively. The floatation of granular sludge could disappear by releasing gas when sludge was in the state of elastic expansion, but it would become worse by holding gas when it entered the plastic expansion state. The plastic expansion of granules was significantly correlated with the less content of extracellular polymeric substances.
authors: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China.
authors: Wei
authors: W
authors: Li
authors: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China. Electronic address: pzheng@zju.edu.cn.
authors: Ping
authors: P
authors: Zheng
authors: College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China.
authors: Junyuan
authors: J
authors: Ji
authors: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China.
authors: Meng
authors: M
authors: Zhang
authors: College of Environmental Science and Engineering, Tongji University, Shanghai 200000, China.
authors: Jun
authors: J
authors: Guo
authors: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China.
authors: Jiqiang
authors: J
authors: Zhang
authors: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China; Department of Chemical Engineering, University of Gujrat, Gujrat, Pakistan.
authors: Ghulam
authors: G
authors: Abbas
mesh_terms: D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D058440:Denitrification; D005740:Gases / Q000032:analysis; D009584:Nitrogen / Q000378:metabolism; D012722:Sewage / Q000382:microbiology; D014865:Waste Disposal, Fluid
chemical_list: D005740:Gases; D012722:Sewage; D009584:Nitrogen
keywords: Floatation mechanism; Granular sludge floatation; High-rate DAC reactor; Working performance