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

1511915(Chen) & 1511941（Li）城市化导致地表面积显著增加，从而防止雨水渗入地下并补充地下水。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），这些污染物最终进入并污染天然水生系统。本研究的一个重要组成部分是研究暴雨期间雨水化学变化和干燥时间长短对生物膜化学性质和微生物多样性的影响，以及生物膜改性工程渗透系统去除细菌的效率。本研究首次系统地研究了在环境相关条件下在工程渗透系统中生长的生物膜对去除雨水中细菌的影响。通过激光共聚焦扫描显微镜和高通量测序技术，将首次揭示不同环境条件下多孔介质中生物膜的结构、分布和微生物多样性的变化。使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粘附在生物膜上的倾向。通过耦合孔隙尺度和连续尺度模型，本工作将定量地将生物膜对孔隙尺度流体动力学的影响与连续尺度上细菌的运输和附着速率联系起来。该研究将为生物膜修饰工程渗透系统中细菌在过滤过程中的滞留机制以及在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，因为它揭示了生物膜的环境条件、物理化学性质和微生物多样性之间的复杂关系，以及细菌与生物膜的相互作用，这将与环境、化学和生物医学工程领域有关。具体任务包括：1)在环境相关条件下在微流体细胞中生长的生物膜的表征；2)利用原子力显微镜探测细菌与生物膜的相互作用；3)柱过滤实验，包括在环境相关条件下培养的生物膜；4)工程渗透系统中流体动力学和细菌去除的孔隙和连续尺度模型。研究结果也将纳入本科和研究生课程材料，并将通过pi及其研究生参与为巴尔的摩内城主要是非裔美国人小学/中学的三年级至五年级学生组织科学活动而得到进一步加强。还将为内布拉斯加州EPSCoR的内布拉斯加州青年科学家夏令营开发与雨水再利用相关的短期课程，该夏令营由K-12学生参加，其中很大一部分是代表性不足的少数民族。

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.