CAREER: Fundamental Investigation of Biofilm Mechanical Properties in Drinking Water Distribution Systems

饮用水分配系统（DWDS）储存和运输经过处理的饮用水给全国数百万客户。在DWDS中，细菌在管道内表面定植并涂覆以形成生物膜，这是造成许多问题的原因，包括腐蚀、味道和气味问题、致癌消毒副产物（DBP）的形成、保护水免受病原微生物侵害的氯残留的损失。所有这些问题都对美国产生了严重的财政和公共卫生影响。该项目旨在对生物膜如何附着在管道上，它们有多强，以及它们如何容易从管道表面分离进行基本的机械理解。这项研究将用于制定从DWDS中去除生物膜的策略，以实现确保公民安全饮用水的国家目标。这项研究对社会的更广泛影响包括为水务公司和水厂运营商开发新的技术解决方案。该项目还旨在让阿拉斯加原住民本科生参与工程研究，长期目标是增加阿拉斯加原住民学生和毕业生的数量并扩大其参与工程的范围。该CAREER项目的研究目标是提高对生物膜机械性能的理解，具体应用于饮用水分配系统（DWDS）中的生物膜。为了实现这一总体目标，该提案有三个目标：（1）调查DWDS中生物膜外聚合物（EPS）基质组分与生物膜强度之间的相关性;（2）测试新的生物膜弱化策略并检查这些弱化策略对DWDS中生物膜对DBP形成的贡献的影响;以及（3）评估分配系统水力学和消毒对DWDS中生物膜脱离、生物膜簇形成和再附着的影响。该项目的主要教育目标是让阿拉斯加土著本科生参与工程研究。 生物膜将在特殊的实验室规模的生物膜生长反应器中生长，该反应器提供模拟分配系统的受控和明确定义的环境条件。先进的显微镜和光谱技术（例如，核磁共振光谱、荧光光谱、共聚焦扫描激光显微镜和原子力显微镜）和生物膜特异性微悬臂梁方法将用于测定EPS组成分析和机械性质。PI还将研究一种通过靶向生物膜EPS来削弱生物膜的新策略，而不是通过使用杀生物剂灭活生物膜细菌的传统方法。为此，将对DWDS中生物膜的一系列强度改性剂和脱附促进剂进行评价。生物膜内聚强度的机理研究将确定各种EPS大分子在提供强度和结构的生物膜中的作用，这将有助于设计有效的生物膜控制策略。对生物膜强度和分离的机械基础的了解将提高我们在各种环境系统中控制和操纵生物膜的能力（例如，生物过滤器、废水处理、DWDS）及其他（例如，医学生物膜）。了解DWDS中的生物膜动力学和分离将有助于设计更好的策略，以提供更好的饮用水质量，显着造福公众health.This奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Drinking water distribution systems (DWDSs) store and transport treated drinking water to millions of customers across the country. Bacteria colonize and coat the inside pipe surfaces in DWDSs to form biofilms that are responsible for a multitude of problems, including corrosion, taste and odor issues, formation of carcinogenic disinfection-by-products (DBPs), loss of the chlorine residual that protects the water from pathogenic microorganisms. All of these problems have serious financial and public health ramifications for the United States. This project aims to develop a fundamental mechanistic understanding of how biofilms attach to pipes, how strong they are, and how easily they can become detached from the pipe surfaces. This research will be used to develop strategies for removal of biofilms from the DWDSs to address the national goal of ensuring safe drinking water to the citizenry. The broader impacts of this research for society include the development of new technological solutions for water utilities and water plant operators. The project also aims to engage Alaska Native undergraduate students in engineering research, with the long-term goal of increasing the number and broadening the participation of Alaska Native students and graduates in engineering.The research goal of this CAREER project is to enhance the understanding of biofilm mechanical properties, with specific application to biofilms in drinking water distribution systems (DWDSs). To meet this overall goal, the proposal has three objectives: (1) investigate the correlation between the biofilm exopolymeric substance (EPS) matrix components and biofilm strength in the DWDS; (2) test novel biofilm weakening strategies and examine the impact of these weakening strategies on the contribution of biofilms to DBP formation in the DWDS; and (3) evaluate the impact of distribution system hydraulics and disinfection on biofilm detachment, biofilm cluster formation and reattachment in the DWDS. A primary educational objective of this project is to involve Alaska Native undergraduate students in engineering research. Biofilms will be grown in special bench-scale biofilm growth reactors that provide controlled and well-defined environmental conditions simulating distribution systems. Advanced microscopic and spectroscopic techniques (e.g., nuclear magnetic resonance spectroscopy, fluorescence spectroscopy, confocal scanning laser microscopy and atomic force microscopy) and biofilm-specific micro-cantilever methods will be employed for determination of EPS compositional analysis and mechanical properties. The PI will also investigate a novel strategy for biofilm weakening by targeting the biofilm EPS, instead of the traditional approach of inactivating biofilm bacteria by using biocides. For that purpose, a suite of strength modifiers and detachment promoting agents for biofilms in DWDSs will be evaluated. The mechanistic study of biofilm cohesive strength will identify the role of various EPS macromolecules in providing strength and structure to biofilms, which will be helpful in designing effective strategies for biofilm control. The insights into the mechanistic basis of biofilm strength and detachment will increase our ability to control and manipulate biofilms in various environmental systems (e.g., biofilters, wastewater treatment, DWDSs) and beyond (e.g., medical biofilms). Understanding biofilm dynamics and detachment in DWDSs will help design better strategies to provide improved drinking water quality, significantly benefitting public health.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.