College of Engineering, Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, Columbus, OH 43210, USA.
Division of Environmental Health Sciences, College of Public Health, The Ohio State University, Columbus, OH 43210, USA; Sustainability Institute, The Ohio State University, Columbus, OH 43210, USA.
Water Res. 2023 Mar 1;231:119612. doi: 10.1016/j.watres.2023.119612. Epub 2023 Jan 15.
Ultraviolet disinfection is a promising solution for decentralized drinking water systems such as communal water taps. A potential health risk is enzymatic photorepair of pathogens after UV disinfection, which can result in regrowth of pathogens. Even though photorepair is a known issue, no formal risk assessments have been conducted for photorepair after UV disinfection in drinking water. The main objective was to construct a quantitative microbial risk assessment (QMRA) of photorepair after UV disinfection of drinking water in a decentralized system. UV disinfection and photorepair kinetics for E. coli were modelled using reproducible fluence-based determinations. Impacts of water collection patterns, and wavelength-dependent water container material transmittance, sunlight intensity, and photorepair enzyme absorbance were quantified. After UV disinfection by 16 or 40 mJ/cm of < 5-log microorganisms per L, risk of infection did not exceed 1-in-10,000 under conditions permitting E. coli photorepair. Risk from photorepair was less than 1-in-10,000 for photorepair light exposure < 0.75 h throughout the day for UV fluence 16 mJ/cm or greater. UV disinfection followed by solar disinfection surpassing photoreactivation during storage reduced risk below 1-in-10,000 for photorepair light exposure > 2.5 h between modelled times of 9 AM - 3 PM. The model can be expanded to other pathogens as UV fluence and photorepair fluence response kinetics become available, and this QMRA can be used to inform the placement of community water access points to reduce risk of photorepair and ensure adequate shelf life of UV disinfected water under safe storage conditions.
紫外线消毒是分散式饮用水系统（如公共水龙头）的一种有前途的解决方案。紫外线消毒后病原体的酶促光修复是一个潜在的健康风险，可能导致病原体再生。尽管光修复是一个已知的问题，但在饮用水紫外线消毒后，尚未对光修复进行正式的风险评估。主要目标是构建分散式系统中饮用水紫外线消毒后光修复的定量微生物风险评估 (QMRA)。使用可重复的基于剂量的测定来模拟大肠杆菌的紫外线消毒和光修复动力学。量化了集水模式、波长相关的水容器材料透过率、阳光强度和光修复酶吸收率的影响。在 16 或 40 mJ/cm 的 < 5 对数微生物/升的紫外线消毒后，在允许大肠杆菌光修复的条件下，感染风险不超过 1/10000。在 16 mJ/cm 或更高的紫外线剂量下，每天暴露于光修复光< 0.75 小时，从光修复中获得的风险小于 1/10000。紫外线消毒后，在储存过程中太阳能消毒超过光复活，可将暴露于光修复光> 2.5 小时的风险降低到 1/10000 以下，模拟时间为上午 9 点至下午 3 点。随着紫外线剂量和光修复剂量响应动力学的发展，该模型可以扩展到其他病原体，并且可以使用此 QMRA 来告知社区供水接入点的位置，以降低光修复风险并确保在安全储存条件下紫外线消毒水的保质期。
