Roles of initial bacterial attachment and growth in the biofouling development on the microfiltration membrane: From viewpoints of individual cell and interfacial interaction energy

In this study, bacterial adhesion and growth behaviors during biofouling development on the polyvinylidene fluoride (PVDF) microfiltration (MF) membrane were investigated. It is recognized that abundance of biomass is essential to the serious biofouling occurrence. The irreversible resistance of membrane increased to 5.2 × 1011 m−1 after filtration of 22 days, and then to 1.42 × 1012 m−1 at the end of 68 days. The growth of bacteria on the membrane surface conformed well to the pseudo second-order kinetic equation, and was mainly determined by the substrates concentration in the feeding. Based on the extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory, the interfacial energy between MF membrane and typical bacteria (Pseudomonas aeruginosa) decreased continuously from 11800 KT (0 h) to −8100 KT (16 h), and the energy barrier decreased gradually after short-term filtration. By chemical cleaning with NaClO and NaOH, the flux of MF membrane recovered to 92.3% and 80.2% of the initial flux, respectively, but the interface energy between membrane and bacteria decreased to −2550 KT and −280 KT, respectively, which accelerated the adhesion of bacteria. This work helps to understand the biofouling mechanisms and provides guidance for the mitigation and control of biofouling for membrane filtration.