紫外联合过硫酸盐杀灭水中大肠杆菌

为提高UV杀菌效率并同时解决UV杀菌存在光复活现象的问题，以大肠杆菌为研究对象，采用UV-PS (紫外联合过硫酸盐) 体系杀灭水中大肠杆菌，研究了各因素对UV-PS体系杀菌效果的影响，并考察复活光强度(0~42 µW·cm⁻²)对不同体系处理后大肠杆菌复活的影响，最后分析其杀菌机理。结果表明：UV-PS体系杀菌效率高于单独UV及单独PS杀菌，15 mJ·cm⁻²紫外剂量下，0.3 mmol·L⁻¹ PS的加入较单独UV杀菌时大肠杆菌对数去除率增加1.0个对数级；且一定范围内大肠杆菌对数去除率随着PS初始浓度的增加而增加；中性条件更有利于大肠杆菌杀灭；Fe²⁺对大肠杆菌杀灭产生抑制效果；大肠杆菌经UV-PS体系处理后光复活能力明显下降，且仅在较强的复活光照下才会产生一定的光复活；UV-PS体系较单独UV杀菌时大肠杆菌细胞形态破坏更为严重，UV-PS体系产生的硫酸根自由基首先攻击细胞表面，使得细胞结构破损，细胞膜破裂，进而对其内容物进行氧化损伤，导致细胞死亡。UV-PS体系杀菌效率高且对大肠杆菌的光复活现象抑制明显，具有一定的应用前景。

Inactivation effect of Escherichia coli by ultraviolet combined with persulfate

In order to improve UV sterilization efficiency and solve the problem of photoreactivation in UV sterilization, ultraviolet (UV) and persulfate (PS) were combined for Escherichia coli (E.coli) inactivation. The effects of different factors on the inactivation were investigated, as well as the effects of different photoreactivating light intensities (0~42 μW·cm−2) on E.coli photoreactivation. The sterilizing mechanism was briefly analyzed. The results showed that E.coli inactivation by UV-PS was more effective than that by UV or PS alone. The addition of 0.3 mmol·L−1 PS elevated the logarithmic removal rate of E.coli by 1.0 lg compared with UV disinfection alone at the dosage of 15 mJ·cm−2. And the logarithmic removal rate of E.coli increased with the initial concentration of PS. The neutral conditions were more conducive to E.coli inactivation, while the presence of Fe2+ had the inhibition effect on E.coli inactivation. The photoreactivation rate of UV-PS disinfected E.coli was much lower than that of UV alone, and only high light intensity could cause the resurrection of some UV-PS disinfected E.coli. The morphological damage of E.coli cells in UV-PS process was more serious than that in UV process. Sulfate free radicals produced by UV-PS first attacked the cell surface, broke the cell structure and ruptured the cell membrane, and then oxidized and destroyed the cellular contents, eventually led to the death of E.coli cell. UV-PS showed high inactivation efficiency and strong inhibition effect on E.coli photoreactivation, and had a promising prospect for practical application.