SusChem: Collaborative Research: Role of Biofilms in Engineered Infiltration Systems in the Removal of Bacteria in Urban Stormwater

1511915(陈)和1511941(李)城市化导致地表显著增加，防止雨水渗入地下并向地下水补给。相反，雨水以地表径流的形式积累，可能导致河床侵蚀和洪水事件。径流还可以从表面吸收污染物(例如病原体)，最终进入并污染自然水生系统。本研究的一个重要组成部分是研究雨水化学成分的变化和干燥时间的长短对生物膜的化学性质和微生物多样性的影响，以及生物膜修饰的工程渗滤系统在暴雨中去除细菌的效率。本研究首次系统地研究了工程渗滤系统中环境相关条件下生长的生物膜对雨水中细菌的去除效果。通过激光共聚焦扫描显微镜和高通量测序，首次揭示了在各种环境条件下生长的多孔介质中生物膜的结构、分布和微生物多样性的变化。利用原子力显微镜测量细菌胶体探针和生物膜之间的界面力，将揭示各种生物膜结构将如何影响细菌和生物膜修饰表面之间的界面相互作用，以及细菌附着在生物膜上的倾向。通过耦合孔隙尺度和连续尺度模拟，本工作将把生物膜对孔隙尺度流体动力学的影响与细菌在连续尺度上的迁移和附着速率定量地联系起来。这项研究将为细菌在过滤过程中的滞留机制以及在生物膜修饰的工程渗透系统中的排水过程中细菌的再动员提供新的见解。这项研究具有变革性，因为它揭示了环境条件、生物膜的物理化学性质和微生物多样性以及细菌-生物膜相互作用之间的复杂关系，这将与环境、化学和生物医学工程领域相关。具体任务包括：1)微流控细胞中环境相关条件下生长的生物膜的表征；2)使用原子力显微镜探测细菌-生物膜的相互作用；3)柱过滤实验，包括在环境相关条件下生长的生物膜；以及4)工程渗透系统中流体动力学和细菌去除的孔和连续尺度模拟。研究成果还将被纳入本科生和研究生课程材料，并通过私人投资机构及其研究生参与为巴尔的摩市中心以非裔美国人为主的小学/中学的三年级至五年级学生组织科学活动而进一步得到加强。还将为内布拉斯加州EPSCoR的年轻内布拉斯加州科学家夏令营开发与雨水回用相关主题的短期课程，K-12学生参加夏令营，其中很大一部分是代表不足的少数族裔。

1511915(Chen) & 1511941(Li)Urbanization has resulted in a significant increase in surfaces which prevent stormwater from infiltrating the subsurface and recharging the groundwater. Instead, stormwater accumulates as surface runoff that can result in streambed erosion and flooding events. The runoff can also pick up contaminants (e.g., pathogens) from the surfaces, which eventually enter and contaminate natural aquatic systems. An important component of this research is to investigate the influence of variation in stormwater chemistry and length of drying periods on the chemical properties and microbial diversity of the biofilms and the efficiency of biofilm-modified engineered infiltration systems to remove bacteria during a storm event.This research is the first to systematically study the effects of biofilms grown under environmentally relevant conditions in engineered infiltration systems on the removal of bacteria from stormwater. The changes in the structure, distribution, and microbial diversity of biofilms in porous media grown under a variety of environmental conditions will be revealed for the first time through confocal laser scanning microscopy and high throughput sequencing. The use of atomic force microscopy for the measurements of interfacial forces between a bacterial colloid probe and biofilms will shed light on how a variety of biofilm structures will influence the interfacial interactions between bacteria and biofilm-modified surfaces and the propensity for bacteria to adhere to biofilms. By coupling pore scale and continuous scale modeling, this work will quantitatively link the influence of biofilms on pore scale hydrodynamics with the rate of bacteria transport and attachment at continuum scale. This research will provide new insights on the mechanisms for bacterial retention during filtration, as well as the remobilization of bacteria during draining in biofilm-modified engineered infiltration systems. This research is transformative because it reveals the intricate relationship between environmental conditions, physicochemical properties and microbial diversity of biofilms, and bacteria-biofilm interactions, which will be relevant to the fields of environmental, chemical, and biomedical engineering. The specific tasks include: 1) characterization of biofilms grown under environmentally relevant conditions in microfluidic cells; 2) probing bacterium-biofilm interactions using atomic force microscopy; 3) column filtration experiments including biofilms grown under environmentally relevant conditions; and 4) pore- and continuum-scale modeling of hydrodynamics and bacterial removal in engineered infiltration systems. Research findings will also be incorporated into undergraduate and graduate course materials and further augmented by the involvement of the PIs and their graduate students in organizing scientific activities for third through fifth-grade students in predominantly African American elementary/middle schools in inner-city Baltimore. Short courses on stormwater reuse-related topics will also be developed for the Nebraska EPSCoR's Young Nebraska Scientists summer camps which are attended by K-12 students, a large fraction of them to be underrepresented minorities.