Membrane fouling in photocatalytic membrane reactors (PMRs) for water and wastewater treatment: A critical review

Photocatalytic membrane reactors (PMRs), as an efficient, low cost and environmentally friendly treatment technology, have shown a great potential to become a zero waste process in water/wastewater industry. At present, the main technical barrier to its commercialization is membrane fouling, which usually increases operating costs and decreases treatment efficiency. This paper reviews R&D progresses in membrane fouling mechanisms of PMRs, relationship between photocatalytic process and membrane fouling, and different fouling control strategies. Fouling evolution, fouling types and fouling consequences in PMRs for different kinds of water/wastewater treatments are summarized. The effects of key operating parameters on fouling behavior, in particular photocatalytic reaction conditions, are discussed, while the role of photocatalysis in membrane fouling mechanism, including pore blocking and cake layer, are critically examined. Furthermore, fouling control strategies in PMRs are reviewed by category. Finally, on the basis of reported results, future research perspectives regarding the development of PMRs and fouling control strategies are proposed. (C) 2016 Elsevier B.V. All rights reserved.