title: New insight into influence of mechanical stirring on membrane fouling of membrane bioreactor: Mixed liquor properties and hydrodynamic conditions.
abstract: Although membrane bioreactor is widely used in wastewater treatment, the problem of membrane fouling remains to be resolved. This paper focused on the influence of mechanical stirring on membrane fouling. Ammonium removal decreased with viscous bulking when stirring rates slowed down. Trans-membrane pressure increased more rapidly when the stirring rate decreased. The resistance of the gel layer increased significantly under low stirring rates, which indicated that the fouling rates of MBR in different stages were attributed to gel layer variation. The proportion of small particles increased when stirring rates slowed down. Furthermore, 16S rRNA gene amplicon sequencing showed that Proteobacteria and Actinobacteria were dominant in the mixed liquor. The relative abundance of Actinobacteria increased from 41% to 50% in the entire experiment. The computational fluid dynamics model was used to simulate the fluid flow characteristics. The model indicated velocities and directions of the fluid flow changes with different stirring rates.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse & School of the Environment Nanjing University, Nanjing 210023, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Qi
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse & School of the Environment Nanjing University, Nanjing 210023, China; Yancheng Institute of Environmental Technology and Engineering of Nanjing University, Yancheng, China. Electronic address: wjnnju@163.com.
authors.forename: Jinnan
authors.initials: J
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse & School of the Environment Nanjing University, Nanjing 210023, China.
authors.forename: Yaohua
authors.initials: Y
authors.lastname: Lin
mesh_terms: D064751:Ammonium Compounds / Q000032:analysis; D001419:Bacteria / Q000378:metabolism; D057219:Biofouling; D057919:Biological Oxygen Demand Analysis; D001704:Biopolymers / Q000737:chemistry; D019149:Bioreactors; D057446:Hydrodynamics; D008567:Membranes, Artificial; D010316:Particle Size; D010802:Phylogeny; D011312:Pressure; D012722:Sewage / Q000737:chemistry; D012995:Solubility; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000302:isolation & purification
chemical_list: D064751:Ammonium Compounds; D001704:Biopolymers; D008567:Membranes, Artificial; D012722:Sewage; D014874:Water Pollutants, Chemical
keywords: Hydrodynamic conditions; Mechanical stirring; Membrane bioreactor; Membrane fouling; Mixed liquor properties