Temporal dynamic of biofouling on the ultrafiltration membrane for wastewater reclamation and strategy for biofouling pertinence mitigation

Abstract

Biofouling deteriorates water quality, increases energy consumption after long-term porous membrane filtration, and shortens membrane lifespan. However, the mechanism of long-term biofouling and corresponding effective anti-biofouling strategies used in municipal wastewater reclamation remains unclear. Herein, the biofouling mechanism was unveiled through revealing the biofouling development and temporal shifts of microbial communities, and correspondingly strategy to mitigate biofouling was proposed to improve initial anti-attachment and to reduce the extracellular matrix content. At the initial stage of biofouling, a sharp drop (68%) in the energy barrier was found according to XDLVO theory, which was attributed to the change of membrane surface due to the formation and colonization of biofilm by Dojkabacteria, Saprospiraceae, Mycobacterium with high EPS secretion capabilities. At the second stage, we demonstrated EPS-protein as the key factors as the main sources that resulted in irreversible community adhesion by Hydrogenophaga and Acinetobacter. At the maturation and aging stage, Bacilli played a vital role in the mature biofilm with fragmentation of the biofouling layer aggregates occurred. Based on the biofouling mechanism, the target anti-biofouling strategy combining PES-PDA-Ag membranes with d-tyrosine was proposed to control biofouling development at the initial and stable stages. This strategy prolonged filtration time about 129%, contributing to at least 94.1% antimicrobial properties and 1.43 times improvement in the energy barrier by disrupting the biofilm integrity to minimize membrane resistance. This finding provides an in-depth understanding of biofouling development and benefits effective and feasible biofouling control.