title: Fouling mechanisms of gel layer in a submerged membrane bioreactor.
abstract: The fouling mechanisms underlying gel layer formation and its filtration resistance in a submerged membrane bioreactor (MBR) were investigated. It was found that gel layer rather than cake layer was more easily formed when soluble microbial products content in sludge suspension was relatively high. Thermodynamic analyses showed that gel layer formation process should overcome a higher energy barrier as compared with cake layer formation process. However, when separation distance <2.3 nm, attractive interaction energy of gelling foulant-membrane combination was remarkably higher than that of sludge floc-membrane combination. The combined effects were responsible for gel layer formation. Filtration tests showed that specific filtration resistance (SFR) of gel layer was almost 100 times higher than that of cake layer. The unusually high SFR of gel layer could be ascribed to the gelling propensity and osmotic pressure mechanism. These findings shed significant light on fouling mechanisms of gel layer in MBRs.
authors.affiliation: College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, PR China.
authors.forename: Huachang
authors.initials: H
authors.lastname: Hong
authors.affiliation: College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, PR China.
authors.forename: Meijia
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Materials Physics, Zhejiang Normal University, Jinhua 321004, PR China.
authors.forename: Yiming
authors.initials: Y
authors.lastname: He
authors.affiliation: College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, PR China.
authors.forename: Jianrong
authors.initials: J
authors.lastname: Chen
authors.affiliation: College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004, PR China. Electronic address: linhonjun@163.com.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Lin
mesh_terms: D057219:Biofouling; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology*; D003102:Colloids / Q000737:chemistry*; D024202:Electrophoretic Mobility Shift Assay; D005374:Filtration; D008567:Membranes, Artificial; D056951:Photoelectron Spectroscopy; D013816:Thermodynamics; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods
chemical_list: D003102:Colloids; D008567:Membranes, Artificial
keywords: Gel layer formation; Interaction energy; Membrane fouling; Osmotic pressure; Specific filtration resistance