Engineering a stable water microbiome in direct potable reuse distribution systems

许多城市面临日益严重的缺水问题。作为回应，这些城市正在制定创新战略，以利用当地替代的饮用水来源。一个有希望的本地来源是经过处理的废水，可以通过高级处理工艺进行净化。与淡化海水一样，这种纯净水也缺少了所有其他饮用水水源中存在的自然细菌群落。纯净水中缺乏天然细菌可能会为不健康的细菌提供滋生的机会。这项研究将比较海水淡化净化饮用水中细菌的稳定性与传统水源水中细菌的稳定性。此外，这项研究还将进行实验室测试，以确定故意向净化废水中添加良性细菌是否可以防止细菌群落的不稳定，就像在供水基础设施中发现的那样。这项工作的发现将帮助工程师计划高纯度水的安全分配，以保护公众，并帮助确保国家的供水。这项研究将通过为代表性不足的学生提供研究和职业发展的机会，扩大对工程学的参与。废水的深度处理可用于直接饮用回用(DPR)，可产生极其纯净的水。虽然DPR水的化学调节以防止管道腐蚀的研究已经在进行中，但很少有人研究DPR对饮用水配水系统(DWDS)微生物的潜在影响。所有的DWDS都有生物膜，添加含有少量细胞的DPR水可能会造成生物不稳定，并有可能滋生机会性病原体。通过播种将良性微生物接种到水中可能有效地降低DWDS中的微生物风险。这项研究将检验故意在深度处理后的水中播种滤料衍生的微生物群落是否会产生更稳定的分配系统微生物群。科学目标是：1)调查美国的全规模分配系统，以检查当前的生物稳定性；2)比较当前两个系统的微生物群落，一个是常规系统，另一个是使用反渗透处理水的系统，在分配过程中；3)表征模拟分配系统在引入混合常规水和DPR水(无论是微生物播种还是非播种)期间微生物群落的变化；以及4)检查消毒剂残留浓度对播种和非播种模拟分配系统中微生物群的影响。本研究将使用基于流式细胞术的细胞计数结合分子方法，包括扩增和元基因组测序，来观察全规模和模拟饮用水配水系统中的微生物变化。这项研究将提供对理论微生物生态学、水微生物组的洞察，并提供有价值的信息，以改进高级处理厂的设计和运营，以供直接饮用。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Many cities face growing water scarcity. In response, these cities are developing innovative strategies to tap into alternative local sources of drinking water. One promising local source is treated wastewater that can be purified through advanced treatment processes. Like desalinated seawater, this purified water is also missing a natural community of bacteria that is present in all other drinking water sources. A lack of natural bacteria in purified water could provide an opportunity for unhealthy bacteria to grow. This study will compare the stability of bacteria in purified drinking water from seawater desalination to bacteria in water from traditional water sources. Additionally, the study will conduct laboratory tests to determine whether deliberately adding benign bacteria to purified wastewater can prevent instability of bacterial communities like those found in water infrastructure. The findings of this work will help engineers plan for the safe distribution of highly purified water to protect the public and help secure the Nation's water supply. The research will broaden participation in engineering by providing opportunities for research and career advancement for underrepresented students. The advanced treatment of wastewater for direct potable reuse (DPR) generates extremely pure water. While the chemical conditioning of DPR water to prevent pipe corrosion is already under study, little work has investigated the potential impacts of DPR on the microbiology of drinking water distribution systems (DWDS). All DWDS harbor biofilms, and the addition of DPR water containing few cells may create biological instability and the potential for growth of opportunistic pathogens. Inoculating water with benign microorganisms via seeding may be effective for decreasing microbial risks in the DWDS. This study will examine whether deliberately seeding advanced treated water with a filter media-derived microbial community results in a more stable distribution system microbiome. The scientific objectives are to: 1) survey full-scale distribution systems in the U.S. to examine current biostability; 2) compare the microbial communities of two current systems, one conventional and one that uses RO-treated water, during distribution; 3) characterize changes to the microbial communities of mock-distribution systems during the introduction of blended conventional water and DPR water that is either microbially seeded or unseeded; and 4) examine the effect of disinfectant residual concentrations on the microbiome in seeded and unseeded mock-distribution systems. This study will use flow cytometry-based cell counting coupled to molecular methods, including amplicon and metagenomic sequencing, to observe microbiological changes in the full-scale and mock drinking water distribution systems. This study will provide insight into theoretical microbial ecology, the water microbiome, and produce valuable information to improve the design and operation of advanced treatment plants for direct potable reuse.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.