Morphological visualization, componential characterization and microbiological identification of membrane fouling in membrane bioreactors (MBRs)

So far, membrane fouling in membrane bioreactors (MBRs) is still not fully understood due to the complex nature of membrane foulants. The challenge to the study of membrane fouling behavior and membrane fouling mechanisms calls for the use and/or development of novel approaches for clearer understanding of membrane foulants such as structure and configuration of fouling layer, physicochemical and biological nature of membrane foulants, and deposition behavior of microorganisms on membranes. As such, MBR fouling can be characterized by the following: (i) visualization of cake morphology, (ii) analysis of chemical composition and, (iii) identification of microbial community structure. The state-of-the-art approaches used for membrane fouling study are critically reviewed in this paper. The advantages and limitations of currently used approaches are discussed as well. Lastly, potential approaches that can be applied for the characterization of membrane fouling in MBRs in the future are mentioned.