Irreversible membrane fouling caused by free TEP: Mitigation performance and mechanism of the integrated MIEX/UF process

Free transparent exopolymer particles (TEP) are an important type of TEP. Researchers have recognized the significant contribution of free TEP to irreversible membrane fouling when treating algae-laden water. Constructing a reasonable process to effectively decelerate membrane fouling caused by free TEP is necessary for the ultrafiltration of algae-laden water. Our experiments indicate that the integrated process of magnetic anion exchange resin (MIEX)/ultrafiltration (UF) can effectively impede the irreversible membrane fouling caused by free TEP. Compared with independent UF, after multi-cycle filtration, the growth rate of hydraulically and chemically irreversible fouling decreased by 40 % and 21 %, respectively, during the MIEX/UF process. The interfacial forces between free TEP and polyvinylidene fluoride (PVDF)/MIEX were determined using atomic force microscopy, and the results showed that the interfacial force of MIEX–free TEP was 4.3-fold higher than that of PVDF–free TEP. Although the adsorption of free TEP by MIEX partly reduced membrane fouling during the MIEX/UF process, the MIEX dynamic layer contributed the most to the alleviation of irreversible membrane fouling during MIEX/UF. Our experimental results provide a more feasible process design for effectively controlling the TEP-induced irreversible membrane fouling.