Emerging investigator series: photocatalytic membrane reactors: fundamentals and advances in preparation and application in wastewater treatment

Abstract

Photocatalytic membrane reactors (PMRs) are a promising treatment technology for degradation of organic compounds discharged from wastewater treatment facilities. This review presents information about TiO₂ nanoparticles, which are the widely used photocatalyst semiconductor in PMRs, and how doping can be used to make TiO₂ able to absorb part of the visible spectrum. Then, many examples are presented showing PMR applications for various feedwater types ranging from dyes, oils, pharmaceuticals, and antibiotic resistant bacteria, either in simulated wastewater or water from real matrices. Although the results are dependent on the feed, photocatalyst, and type of reactor, the PMR technology can achieve removal efficiency higher than 95% for some situations. PMRs have also shown antimicrobial properties in removing 99.9% of antibiotic-resistant bacteria in one study presented. Additionally, PMRs have demonstrated antifouling properties due to their surface modification – resulting in their reuse and extended lifespan. Although photocatalytic membrane reactors can achieve quantitative removal in some feed water types, more development is needed before employing them for more widespread wastewater treatment. In this sense, the article ends with a perspective section where some possible advances in the photocatalyst and reactor design are suggested which can expand the range of PMR applications.