VUV coupled with low-dose H 2 O 2 as pretreatment prior to UF: Performance, mechanisms, DBPs formation and toxicity evaluation.

Ultrafiltration (UF) is widely used in drinking water plants; however, membrane fouling is unavoidable. Natural organic matter (NOM) is commonly considered as an important pollutant that causes membrane fouling. Herein, we proposed VUV/H ₂ O ₂ as a UF pretreatment and used UV/H ₂ O ₂ for comparison. Compared to UV/H ₂ O ₂ , the VUV/H ₂ O ₂ system presented superior NOM removal. In the VUV/H ₂ O ₂ system, the steady-state concentration of HO• was approximately twice that in the UV/H ₂ O ₂ system, which was ascribed to the promoting effect of the 185 nm photons. Specifically, 185 nm photons promoted HO• generation by decomposing mainly H ₂ O at a low H ₂ O ₂ dose or by decomposing mainly H ₂ O ₂ at a high H ₂ O ₂ dose. The VUV/H ₂ O ₂ pretreatment also demonstrated better membrane fouling mitigation performance than did UV/H ₂ O ₂ . An increase in the H ₂ O ₂ dose promoted HO• generation, thereby enhancing the performance of NOM degradation and membrane fouling alleviation and shifting the major membrane fouling mechanism from cake filtration to standard blocking. The VUV/H ₂ O ₂ (0.60 mM) pretreatment effectively reduced disinfection byproducts (DBPs) formation during chlorine disinfection. Additionally, the oxidant H ₂ O ₂ affected the membrane surface morphology and performance but had no evident effect on the mechanical properties. In actual water treatment, the VUV/H ₂ O ₂ pretreatment exhibited better performance than the UV/H ₂ O ₂ pretreatment in easing membrane fouling, ameliorating water quality, and reducing DBPs formation and acute toxicity.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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