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Abstract：
The ubiquitous presence of biofilms in premise plumbing and stagnation, which commonly occurs in premise plumbing, can exacerbate the decay of chlorine residual in drinking water. Using biofilms grown in a simulated premise plumbing setup fed directly with freshly treated water at two full-scale water treatment plants, we previously determined the mass transfer coefficients for chlorine decay in premise plumbing. These coefficients coupled with inactivation kinetics of L. pneumophila released from biofilms reported previously were integrated into a Monte Carlo framework to estimate the infection risk of biofilm-derived L. pneumophila from 1 to 48 h of stagnation. The annual infection risk was significantly higher when water stayed stagnant for up to 48 h in pipes covered internally with biofilms, compared to clean pipes without biofilms. The decay of residual chlorine due to biofilms during 48-hour stagnation led to up to 6 times increase in the annual infection risk compared to the case where biofilms was absent. Global sensitivity analysis revealed that the rate of L. pneumophila detachment from biofilms and the decay of chlorine residual during stagnation are the two most important factors influencing the infection risks. Stagnation caused by water use patterns and water-saving devices in the premise plumbing can lead to increased infection risk by biofilm-derived L. pneumophila. Overall, this study\'s findings suggested that biofilms could induce chlorine decay and consequently increase L. pneumophila infection risk. Thus, reducing stagnation, maintaining residual chlorine, and suppressing biofilm growth could contribute to better management of L. pneumophila infection risk.
摘要：
在管道和停滞前提下普遍存在生物膜，通常发生在前提管道中，会加剧饮用水中残留氯的腐烂。在两个全面的水处理厂中，使用在模拟的前提管道装置中直接用新鲜处理的水喂养的生物膜，我们先前确定了前提管道中氯衰变的传质系数。这些系数与先前报道的从生物膜中释放的嗜肺乳杆菌的失活动力学相结合，被整合到MonteCarlo框架中，以估计停滞1至48小时内生物膜衍生的嗜肺乳杆菌的感染风险。当水在内部覆盖有生物膜的管道中停滞长达48小时时，年度感染风险显着升高。与没有生物膜的清洁管道相比。与没有生物膜的情况相比，在48小时停滞期间由于生物膜而导致的残留氯的衰减导致年度感染风险增加了多达6倍。全球敏感性分析显示，嗜肺杆菌从生物膜中脱离的速率和停滞期间氯残留的衰减是影响感染风险的两个最重要因素。由前提管道中的用水模式和节水装置引起的停滞可导致生物膜衍生的嗜肺乳杆菌感染风险增加。总的来说,这项研究的结果表明，生物膜可以诱导氯气衰变，从而增加嗜肺乳杆菌感染的风险。因此，减少停滞，保持余氯，抑制生物膜的生长可能有助于更好地控制嗜肺乳杆菌感染的风险。
