A review on oxidation pretreatment for mitigating ultrafiltration membrane fouling caused by natural organic matter in water treatment.

Ultrafiltration (UF) is a promising water treatment technology due to its low energy consumption, cost-effectiveness, and efficient removal of microbial contaminants. However, membrane fouling caused by natural organic matter (NOM), which is ubiquitous in aquatic environments, remains a major operational challenge. Oxidation pretreatment prior to UF enhances performance by integrating oxidative degradation with membrane separation, offering an effective strategy for fouling mitigation. This work provides a review of various oxidation pretreatment technologies prior to UF, from the perspective of unitary to multicomponent systems, based on an understanding of NOM characteristics and membrane fouling mechanisms. Binary and ternary oxidation systems demonstrate superior membrane fouling mitigation efficacy compared to unitary oxidation systems due to the combined contributions of multiple components, with binary pretreatment being the most extensively studied. Furthermore, oxidation pretreatment mitigates fouling mainly by oxidation, and potentially also by coagulation or adsorption. This potential combined effect plays a crucial role in mitigating membrane fouling by altering the properties of NOM in UF influent and/or modifying the membrane surface characteristics, with oxidation serving as the dominant function. To further advance the application of UF process, upcoming studies ought to concentrate on the following areas: the impact of pretreatment residues, the influence of pretreatment on effluent quality, the enhancement of pilot-scale studies, the integration of artificial intelligence assistance, and comprehensive evaluation. Overall, this review offers a comprehensive analysis of oxidation pretreatment in mitigating UF membrane fouling, providing valuable guidance for the development and application of oxidation pretreatment technologies in UF membrane-based water treatment.