Priority bacteria causing biofouling of reverse osmosis membranes: Potential disinfection-resistant bacteria and control strategies

What bacteria cause membrane biofouling in engineering practice? This is the fundamental question in the research on biofouling, which is the Achilles' heel of the reverse osmosis (RO) system. If this question is not addressed clearly, the subsequent research on mechanism interpretation and possible control technologies is questionable due to the lack of appropriate research objects. However, a uniform conclusion has not yet been given, as it varied considerably in different studies. Here, to better cope with RO membrane biofouling introduced by microbiomes, 46 genera of residual microorganisms that tend to adhere to the surface of RO membranes were summarized. Interestingly, disinfection-resistant bacteria (DRB) accounted for 75 % of those reported with high and medium frequency. From the perspective of frequency of occurrence, phylogenetic relationship, and co-occurrence network analysis of membrane-attached residual microorganisms, the fundamental characteristics were identified to recognize the priority bacteria in common. Further, a series of undesirable risks posed by DRB on the level of harmful genes transfer were highlighted. Correspondingly, feasible control strategies to effectively alleviate biofouling and their application in RO systems were discussed. This work identified priority species and their detrimental effects on RO membrane biofouling and provided new insights to solve the inevitable issue.