UV irradiation and chlorination have been widely used for water disinfection. However, there are some limitations, such as the risk of generating viable but nonculturable bacteria and bacteria reactivation when using UV irradiation or chlorination alone. This study comprehensively evaluated the feasibility of the UV/chlorine process in drinking water disinfection, and Pseudomonas aeruginosa was selected as the target microorganism. The number of culturable cells was effectively reduced by more than 5 orders of magnitude (5-log₁₀) after UV, chlorine, and UV/chlorine treatments. However, intact and VBNC cells were detected at 10³ to 10⁴ cells/mL after UV and chlorine treatments, whereas they were undetectable after UV/chlorine treatment due to the primary contribution of reactive chlorine species (Cl^•, Cl₂^•–, and ClO^•). After UV/chlorine treatment, the metabolic activity determined using single cell Raman spectroscopy was much lower than that after UV. The level of toxic opr gene in P. aeruginosa decreased by more than 99% after UV/chlorine treatment. Importantly, bacterial dark reactivation was completely suppressed by UV/chlorine treatment but not UV or chlorination. This study suggests that the UV/chlorine treatment can completely damage bacteria and is promising for pathogen inactivation to overcome the limitations of UV and chlorine treatments alone.

中文翻译：

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铜绿假单胞菌消毒中紫外线/氯过程的评估：效率和机制

紫外线照射和氯化已广泛用于水消毒。但是，也存在一些限制，例如单独使用紫外线照射或氯化时会产生可存活但不可培养的细菌和细菌再激活的风险。本研究综合评估了紫外线/氯工艺在饮用水消毒中的可行性，并选择铜绿假单胞菌作为目标微生物。经过紫外线、氯和紫外线/氯处理后，可培养细胞的数量有效减少了 5 个数量级以上 (5-log ₁₀ )。然而，在 10 ³至 10 ⁴检测到完整和 VBNC 细胞UV 和氯处理后的细胞/mL，而由于活性氯物质（Cl ^•、Cl ₂ ^•–和 ClO ^•）的主要贡献，它们在 UV/氯处理后无法检测到。UV/氯处理后，使用单细胞拉曼光谱测定的代谢活性远低于UV处理后的代谢活性。铜绿假单胞菌毒性opr基因水平紫外线/氯处理后降低了 99% 以上。重要的是，紫外线/氯处理完全抑制了细菌暗激活，但紫外线或氯化处理却没有。这项研究表明，紫外线/氯处理可以完全破坏细菌，并有望使病原体灭活，以克服单独使用紫外线和氯处理的局限性。