title: Single-stage versus two-stage anaerobic fluidized bed bioreactors in treating municipal wastewater: Performance, foulant characteristics, and microbial community.
abstract: This study examined the receptive performance, membrane foulant characteristics, and microbial community in the single-stage and two-stage anaerobic fluidized membrane bioreactor (AFMBR) treating settled raw municipal wastewater with the aims to explore fouling mechanisms and microbial community structure in both systems. Both AFMBRs exhibited comparable organic removal efficiency and membrane performances. In the single-stage AFMBR, less soluble organic substances were removed through biosorption by GAC and biodegradation than those in the two-stage AFMBR. Compared to the two-stage AFMBR, the formation of cake layer was the main cause of the observed membrane fouling in the single-stage AFMBR at the same employed flux. The accumulation rate of the biopolymers was linearly correlated with the membrane fouling rate. In the chemical-cleaned foulants, humic acid-like substances and silicon were identified as the predominant organic and inorganic fouants respectively. As such, the fluidized GAC particles might not be effective in removing these substances from the membrane surfaces. High-throughout pyrosequencing analysis further revealed that beta-Proteobacteria were predominant members in both AFMBRs, which contributed to the development of biofilms on the fluidized GAC and membrane surfaces. However, it was also noted that the abundance of the identified dominant in the membrane surface-associated biofilm seemed to be related to the permeate flux and reactor configuration.
authors.affiliation: Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore, 637141, Singapore. Electronic address: wubing@ntu.edu.sg.
authors.forename: Bing
authors.initials: B
authors.lastname: Wu
authors.affiliation: Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore, 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
authors.forename: Yifei
authors.initials: Y
authors.lastname: Li
authors.affiliation: Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore, 637141, Singapore.
authors.forename: Weikang
authors.initials: W
authors.lastname: Lim
authors.affiliation: School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
authors.forename: Shi Lin
authors.initials: SL
authors.lastname: Lee
authors.affiliation: Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore, 637141, Singapore.
authors.forename: Qiming
authors.initials: Q
authors.lastname: Guo
authors.affiliation: Singapore Membrane Technology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore, 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.
authors.forename: Anthony G
authors.initials: AG
authors.lastname: Fane
authors.affiliation: Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 Cleantech Loop, CleanTech One #06-08, Singapore, 637141, Singapore; School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore. Electronic address: cyliu@ntu.edu.sg.
authors.forename: Yu
authors.initials: Y
authors.lastname: Liu
mesh_terms: D000693:Anaerobiosis; D018441:Biofilms; D001704:Biopolymers; D019149:Bioreactors / Q000382:microbiology; D008567:Membranes, Artificial; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater
chemical_list: D001704:Biopolymers; D008567:Membranes, Artificial; D062065:Wastewater
keywords: Anaerobic MBR; Bacterial diversity; Granular activated carbon; Membrane fouling; Scouring