Development of ultraviolet disinfection systems to reduce photoreactivation of microorganisms in water

用低压紫外灯(LP；254 nm)和中压紫外灯(MP，220 nm-580 nm)对大肠杆菌、微小隐孢子虫和嗜肺军团菌的紫外线灭活和光复活进行了比较。还对MP排放物进行了过滤，以考察波长对微生物灭活和光复活特性的影响。采用核酸内切酶敏感部位分析法检测紫外线诱导的嘧啶二聚体在基因组DNA中的数量，同时采用常规培养或感染力测定来研究微生物的生存能力。研究表明：(L)微小弧菌可以被紫外线有效灭活，而不需要光复活；(2)MP灯可能通过影响光解酶来抑制大肠杆菌的光复活；(3)嗜肺乳杆菌在LP灯或MP灯灭活后都表现出明显的光复活。这些结论可能会促进具有高消毒效率和低光复活风险的紫外线系统的发展。

Ultraviolet inactivation and photoreactivation of Escherichia coli, Cryptosporidium parvum and Legionella pneumophila were compared using a low-pressure UV lam (LP ; 254nm) or a medium-pressure UV lamp (MP ; 220nm-580nm). Filtration of the MP emissions was also carried out to investigate the effect of wavelengths on the characteristics of inactivation and photoreactivation of microorganisms. An endonuclease sensitive site (ESS) assay was applied to determine the number of UV-induced pyrimidine dimers in the genomic DNA, while a conventional cultivation or infectivity assay was also used to investigate the viability of microorganisms.This research indicated that (l) C. parvum can be effectively inactivated by UV without photoreactivation, (2) MP lamp can repress photoreactivation of E. coli probably by affecting photolyase (3) L. pneumophila performs evident photoreactivation either after LP or MP lamp inactivation. These conclusions may encourage a development of UV systems with high disinfection efficiency at low photoreactivation risk.