VUV-activated periodate pretreatment for membrane fouling mitigation in secondary effluent: performance and mechanisms

Vacuum ultraviolet/periodate (VUV/PI) was proposed to pretreat secondary effluent. • VUV/PI oxidation pretreatment achieved a 48% removal of DOC in secondary effluent. • VUV/PI pretreatment increased the flux of ultrafiltration membrane by 82.8%. • VUV/PI mitigated surface fouling by reducing pollutant concentration and adhesion. • • OH, 1 O 2 , and O 3 were the primary reactive species to degrade BPA in VUV/PI. Ultrafiltration (UF) membrane fouling caused by dissolved organic matter from secondary effluent is a thorny problem. To address this issue, this study constructs a vacuum ultraviolet/periodate (VUV/PI) advanced oxidation pretreatment system. The synergistic system operates via direct photolysis of water and indirect oxidation, while VUV enhances the activation efficiency compared with conventional UV. Following VUV/PI pretreatment, fluorescent components in the water samples were reduced. The DOC removal rate reached 48%, indicating that the natural organic matters, the dominant membrane foulants in secondary effluent, was partially eliminated. The terminal specific flux was effectively improved by 82.8%, and the total fouling resistance decreased by 60%. The reactive species generated by VUV radiation activation of PI, such as • OH, 1 O 2 , and O 3 , contributed to organic matter degradation; concurrently, the interfacial free energy between contaminants and membrane surface decreased from −55.22 to −40.98 mJ/m 2 , which also reduced the attractive force between them in part. The results indicate that the VUV/PI system can effectively improve effluent water quality and significantly mitigate membrane fouling. This study provides an efficient pretreatment technology for UF membrane fouling control in the advanced treatment of secondary effluent. Download: Download high-res image (198KB) Download: Download full-size image