RAPID: Assessing microbiological quality across point-of-use filters deployed in Flint, Michigan

1632974爱水和废水处理行业面临的主要问题之一是老化的基础设施，有人估计这是一个万亿美元的问题，需要在未来几年解决。密歇根州弗林特市目前正遭受一场“完美风暴”，原因是其饮用水分配系统的腐蚀失控。除了对铅的担忧外，水中还有过量的消毒副产物，而且，与饮用水相关的细菌质量差也令人担忧。作为保护消费者的一项措施，安装在垃圾桶上的使用点过滤器正在以前所未有的规模在城市中长期使用。该项目将调查弗林特水的使用点过滤器，特别关注夏季水和基础设施变暖时可能发生的变化。维护良好的使用点设备肯定会去除一些化学水污染物;然而，微生物污染物通常相反。此前，PI在多次重复测试中显示，即使按照制造商指南使用过滤器，使用点过滤器也会增加饮用水中微生物群落的丰度并改变其组成。PI的工作还表明，微量的替代不受管制的消毒副产品改变了使用点过滤器流出物中微生物群落的组成，这表明饮用水中的污染物与使用点设备的使用相结合改变了消费者暴露的微生物风险。在弗林特的情况下，不知道从腐蚀期恢复分配系统和房屋管道将如何影响应用于使用点过滤器的微生物水质，以及进水变化将如何反过来影响过滤器产生的水的微生物质量。此外，认为水龙头上的单个使用点装置就足够了是不合理的，因为它没有实现传统的饮用水处理范例，即使用多个处理屏障来保护公众健康免受多种污染物的影响。PI拥有丰富的经验，可以使用一系列现有方法询问弗林特使用的过滤器，以了解水质、微生物丰度和成分的变化，并可以快速动员。PI建议在2016年春季，夏季和秋季在密歇根州弗林特完成水龙头安装的使用点过滤器的采样活动，以评估使用点处理水的微生物质量变化。这些分析将包括基于培养和不依赖培养的方法，以确定可能影响公共卫生的微生物群落组成、特定物种和/或基因。据推测，在夏季，整个系统中的微生物生长水平会更高。先前的研究表明，过滤器外壳中的分枝杆菌（已知包括机会致病菌的细菌家族）水平显著升高，过滤器流出物中的水平中度但显著增加。使用点过滤器在减轻化学污染物方面的重要性是公认的，但需要平衡以实现可接受的微生物水质。鉴于弗林特饮用水管道腐蚀损坏对分布式水中微生物质量和消毒剂残留的未知后果，重要的是要评估使用点过滤器的微生物质量，以建立良好的监测和过滤器维护实践，以帮助制定弗林特使用点过滤器维护策略，这是我们提出的努力的主要成果。这一点尤其重要，因为过滤器的使用预计将持续数月，因此必须立即并在今年剩余时间内进行。

1632974LoveOne of the major issues facing the water and wastewater industry is aging infrastructure, some estimate that this is a one trillion dollar issue to be solved in the coming years. Flint, MI, is currently suffering from a "perfect storm" attributable to out-of-control corrosion of its potable water distribution system. In addition to concerns about lead, there are excessive disinfection by-products in the water, and, the poor bacterial quality associated with drinking water is also of concern. As one measure of protection to consumers, faucet-mounted point-of-use filters are being deployed for long-term use in the city at a scale not previously seen in the US. This project will investigate point-of-use filters for Flint water, with particular attention to the potential for changes as the water and infrastructure warm in the summer months.Well maintained point-of-use devices will certainly remove some of the chemical water contaminants; however, the opposite is typically true for microbiological contaminants. Previously, the PIs have shown in multiple and repeated tests that point-of-use filters increase the abundance and alter the composition of microbial communities in drinking water, even when filters are used in accordance with manufacturer guidelines. The PIs work has also shown that trace levels of a surrogate unregulated disinfection by-product altered the composition of the microbial community in the effluent of a point-of-use filter, suggesting that contaminants in the drinking water coupled with use of a point-of-use device alters the microbial risk a consumer is exposed to. In the case of Flint, it is not known how recovery of the distribution system and premise plumbing from the corrosion period will impact the microbial water quality applied to the point-of-use filters, and how influent changes will, in turn, influence the microbial quality of the water produced by the filter. Furthermore, it is unreasonable to think that a single point-of-use device on a faucet is sufficient, given that it does not achieve the conventional drinking water treatment paradigm that is to use multiple treatment barriers to protect public health from multiple contaminants. The PIs have extensive experience interrogating point-of-use filters like those used in Flint for changes in water quality, microbial abundance and composition using a range of current methods and can mobilize quickly. The PIs propose to complete a sampling campaign of faucet mounted point-of-use filters in Flint, Michigan over the spring, summer and fall 2016 to evaluate changes in the microbiological quality of point-of-use-treated water. The analyses will include culture-based and culture-independent methods to determine microbial community composition, specific species and/or genes that can impact public health. It is hypothesized that there will be higher levels of microbial growth across the system during the summertime. Previous studies showed significantly elevated levels of Mycobacterium, a family of bacteria known to include opportunistic pathogens, in the filter housing and moderate yet significant increases in the filter effluent. The importance of point-of-use filters in mitigating the chemical contaminants of concern is acknowledged, but a balance is needed to achieve acceptable microbiological water quality. Given the unknown consequences of the corrosion damage of Flints drinking water pipes on the microbial quality and disinfectant residuals in the distributed water, it is important to evaluate the microbiological quality of point-of-use filters in order to establish good monitoring and filter maintenance practices to assist in setting a point-of-use filter maintenance strategy for Flint, which is a major outcome of our proposed effort. This is particularly important to engage in immediately and through the rest of this year since the use of filters is expected to continue for several months.