Department of Civil and Environmental Engineering, Northeastern University, Boston, MA, United States of America.
Department of Civil and Environmental Engineering, Virginia Tech, Blacksburg, VA, United States of America.
Sci Total Environ. 2020 Jun 10;720:137451. doi: 10.1016/j.scitotenv.2020.137451. Epub 2020 Feb 20.
After flooding events, well users are encouraged to disinfect their private wells. However, well disinfection strategies are not consistently applied or proven effective. This study examines the science-based evidence that disinfection procedures reduce microbial loading in well water; reviews inclusion of disinfection principles in state-level emergency protocols; and explores research gaps potentially hindering disinfection efficacy. Emergency well disinfection protocols from 34 states were reviewed based on instructions for creating chlorine solutions; circulating chlorine solutions throughout the distribution system; achieving effective CT disinfection (chlorine dose*contact time); and post-disinfection guidance. Many protocols were missing key information about fundamentals of disinfection. Only two protocols instructed well users to verify chlorine residuals and three protocols instructed users to measure water pH. Most protocols recommended that high chlorine doses be introduced into the well, circulated throughout the system, and stagnated for several hours. A CT value estimated to inactivate at least 99.9% (3-log removal) of Cryptosporidium (255 mg-hr/L) was predicted to be achieved by 72.7% of protocols, and estimated CT values ranged from 35 to 16,327 mg-hr/L. Two research gaps identified were determining whether chlorine doses should differ based on well water chemistries and evaluating the appropriate chlorine dose that should be recommended for inactivating pathogens. This effort underscores a need for consistent, evidence-based messaging in emergency well disinfection protocols.
洪水事件后，鼓励水井用户对其私人水井进行消毒。然而，水井消毒策略并未得到一致应用或被证明是有效的。本研究考察了消毒程序可降低井水微生物负荷的科学依据；审查了将消毒原则纳入州级紧急预案的情况；并探讨了可能阻碍消毒效果的研究空白。根据制备氯溶液的说明、在分配系统中循环氯溶液、达到有效 CT 消毒（氯剂量*接触时间）以及消毒后指导，对 34 个州的紧急水井消毒预案进行了审查。许多预案缺少消毒基本原理的关键信息。只有两份预案指示水井用户验证余氯，三份预案指示用户测量水的 pH 值。大多数预案建议将高剂量的氯引入水井，在系统中循环，并停滞数小时。据预测，72.7%的预案能达到估计值为至少灭活 99.9%（3 对数去除）隐孢子虫（255 mg-hr/L）的 CT 值，估计 CT 值范围为 35 至 16327 mg-hr/L。确定是否应根据井水化学成分来调整氯剂量以及评估推荐用于灭活病原体的适当氯剂量这两个研究空白。这项工作强调了在紧急水井消毒预案中需要有一致的、基于证据的信息传递。
