Understanding Mechanisms of Membrane Biofouling in Anaerobic Membrane Bioreactors Using Polymer Surface Dissection

厌氧膜生物反应器（AnMBR）可用作废水处理的低能耗方法，以产生可再生能源和高质量的水用于再利用。然而，这些生物反应器受到膜污染的限制，所述膜污染部分地由废水中细菌的附着引起，所述细菌的附着导致在膜表面形成生物膜。这种结垢占AnMBR能源使用的50%。该项目的目标是发现和表征在AnMBR膜表面上启动生物膜形成的关键细菌，了解这些细菌如何在污染过程中修改膜，并确定膜的物理特性，使其易于生物污染。从这些研究中获得的知识将为改进的膜和膜处理策略的设计提供信息，这些策略将使AnMBR在废水处理设施，农业工业和限制动物饲养操作中的经济和可持续使用取得进展。该项目将利用堪萨斯路易斯斯托克斯少数民族参与联盟和发展中学者计划，从堪萨斯农村社区学院招募和留住少数民族学生，在堪萨斯州立大学进行为期一年的暑期实习，为他们在可持续环境研究和技术方面的职业生涯做准备。如果成功，该项目将有助于推进水处理技术，以保护国家的水供应和能源安全。本研究的目的是发现微生物，启动生物污染的膜在厌氧膜生物反应器（AnMBR）和表征其分子污染策略。虽然许多努力都集中在开发化学和物理处理方法，以减轻生物污垢，驱动生物膜形成的基本机制的理解有限的长期战略，以减轻这些膜表面的污垢。核心假设是，早期生物污损是由AnMBR社区成员的一个亚组驱动的，该亚组通过分泌胞外多糖和可溶性微生物产物来局部修饰膜表面。为了检验这一假设，将研究使用一种新型的非破坏性方法，该方法使用生物相容性聚合物材料从膜表面去除活细胞，称为聚合物表面解剖（PSD）。PSD方法将能够以空间受控的方式从膜表面精确地切片早期定殖体，用于细胞培养和微生物鉴定。这将与使用扫描电子显微镜和能量色散X-射线光谱对膜表面上的相应污染位点的物理化学分析相结合。PSD方法将用于表征使用合成废水的实验室环境中的污垢。这些研究结果将与中试规模AnMBR反应器系统的数据进行比较，以了解现实的环境变量对膜生物污损的影响。从这些研究中获得的知识将为抑制特定生物的合理AnMBR操作和处理策略提供信息，并将导致开发改进的防污膜材料。除了这些实验室和中试规模的系统，PSD方法也可以用来揭示其他废水处理系统中的微生物组装机制，其中生物污垢是一个限制性的问题。该奖项反映了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。

Anaerobic membrane bioreactors (AnMBRs) can be used as a low-energy approach to wastewater treatment to produce renewable energy and high-quality water for reuse. However, these bioreactors are limited by membrane fouling caused in part by the attachment of bacteria in wastewater that leads to formation of biofilms at the membrane surface. This fouling accounts for 50% of the AnMBR energy use. The goal of this project is to discover and characterize the key bacteria that initiate biofilm formation on AnMBR membrane surfaces, learn how these bacteria modify the membrane during the fouling process, and identify the physical characteristics of the membrane that make it prone to biofouling. The knowledge gained from these studies will inform the design of improved membranes and membrane treatment strategies that will progress AnMBRs toward economical and sustainable use in wastewater treatment facilities, agro-based industries, and confined animal feeding operations. The project will use the Kansas Louis Stokes Alliance for Minority Participation and the Developing Scholars Program to recruit and retain minority students from rural community colleges in Kansas for summer and year-long internships at Kansas State University, preparing them for careers in sustainable environmental research and technology. If successful, this project will help advance water treatment technologies to protect the Nation's water supply and energy security.The objective of this research is to discover microorganisms that initiate biofouling on membranes in anaerobic membrane bioreactors (AnMBRs) and to characterize their molecular fouling strategies. While much effort has focused on developing chemical and physical treatment methods to alleviate biofouling, a poor understanding of the fundamental mechanisms that drive biofilm formation limit long-term strategies to mitigate fouling over these membrane surfaces. The central hypothesis is that early-stage biofouling is driven by a sub-group of AnMBR community members that locally modify the membrane surface through secretion of exopolysaccharides and soluble microbial products. To test this hypothesis, the use of a novel, non-destructive method that uses biocompatible polymeric materials to remove live cells from the membrane surface, termed polymer surface dissection (PSD), will be investigated. The PSD method will enable precise sectioning of early colonizers from the membrane surface in a spatially controlled manner for cell cultivation and microbial identification. This will be coupled with physicochemical analyses of the corresponding fouling sites on the membrane surface using scanning electron microscopy and energy dispersive X-ray spectroscopy. The PSD approach will be used to characterize fouling in a laboratory setting using synthetic wastewater. These findings will be compared with data from a pilot-scale AnMBR reactor system to understand the effect of realistic environmental variables on membrane biofouling. The knowledge gained from these studies will inform rational AnMBR operation and treatment strategies that inhibit specific organisms, and will lead to the development of improved anti-fouling membrane materials. Beyond these bench and pilot scale systems, the PSD method can also be used to uncover microbial assembly mechanisms in other wastewater treatment systems where biofouling is a limiting issue.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.