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

饮用水分配系统（DWDSs）储存和运输处理过的饮用水给全国数百万的客户。细菌在dwds内管道表面定植并覆盖，形成生物膜，导致许多问题，包括腐蚀，味道和气味问题，致癌消毒副产物（DBPs）的形成，保护水免受病原微生物侵害的氯残留量的损失。所有这些问题都给美国带来了严重的财政和公共卫生后果。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的机制有一个基本的理解。这项研究将用于制定从dwds中去除生物膜的战略，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。该项目还旨在吸引阿拉斯加土著本科生参与工程研究，其长期目标是增加和扩大阿拉斯加土著学生和毕业生参与工程的数量。本CAREER项目的研究目标是加强对生物膜力学特性的理解，并具体应用于饮用水分配系统（DWDSs）中的生物膜。为了实现这一总体目标，该提案有三个目标：(1)研究生物膜外聚合物（EPS）基质成分与DWDS中生物膜强度之间的相关性；(2)测试新的生物膜弱化策略，并研究这些弱化策略对生物膜对DWDS DBP形成的贡献的影响；(3)评价配电系统水力学和消毒对污水处理厂生物膜脱离、生物膜簇形成和再附着的影响。本计画的主要教育目标是让阿拉斯加原住民本科生参与工程研究。生物膜将在特殊的实验规模的生物膜生长反应器中生长，该反应器提供可控和良好定义的环境条件，模拟分布系统。先进的显微和光谱学技术（如核磁共振光谱学、荧光光谱学、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方法将被用于测定EPS的成分分析和力学性能。PI还将研究一种新的生物膜弱化策略，即通过靶向生物膜EPS来取代传统的使用杀菌剂灭活生物膜细菌的方法。为此，我们将对DWDSs中生物膜的一套强度调节剂和分离促进剂进行评估。通过对生物膜内聚强度的机理研究，可以明确各种EPS大分子在生物膜内聚强度和结构方面的作用，有助于设计有效的生物膜调控策略。对生物膜强度和分离机制基础的深入了解将提高我们在各种环境系统（如生物过滤器、废水处理、dwds）和其他环境系统（如医疗生物膜）中控制和操纵生物膜的能力。了解dwds中的生物膜动力学和脱离将有助于设计更好的策略，提供改善的饮用水质量，显著有利于公众健康。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

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.