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

厌氧膜生物反应器（anmbr）是一种低能耗的污水处理方法，可以产生可再生能源和高质量的水供回用。然而，这些生物反应器受到膜污染的限制，部分原因是废水中的细菌附着导致膜表面形成生物膜。这种结垢占AnMBR能耗的50%。该项目的目标是发现并表征引发AnMBR膜表面生物膜形成的关键细菌，了解这些细菌在污染过程中如何修饰膜，并确定膜的物理特性，使其易于发生生物污染。从这些研究中获得的知识将为改进膜和膜处理策略的设计提供信息，这些策略将推动anmbr在废水处理设施、农业工业和限制性动物饲养操作中实现经济和可持续的使用。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学者计划，从堪萨斯州农村社区学院招募和留住少数民族学生，让他们在堪萨斯州立大学进行暑期和一年的实习，为他们从事可持续环境研究和技术方面的职业做好准备。如果成功，该项目将有助于推进水处理技术，以保护美国的水供应和能源安全。本研究的目的是发现在厌氧膜生物反应器（anmbr）中引发膜生物污染的微生物，并表征它们的分子污染策略。虽然人们致力于开发化学和物理处理方法来减轻生物污染，但对驱动生物膜形成的基本机制的了解不足，限制了减轻这些膜表面污染的长期策略。核心假设是，早期的生物污染是由AnMBR群落成员的一个亚群驱动的，这些亚群通过分泌外多糖和可溶性微生物产物局部修饰膜表面。为了验证这一假设，将研究一种新的非破坏性方法，即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方法将能够以空间控制的方式从膜表面精确切片早期定植体，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射线光谱学对膜表面相应的污染部位进行物理化学分析相结合。PSD方法将用于表征实验室环境中使用合成废水的污染。这些发现将与中试规模的AnMBR反应器系统的数据进行比较，以了解实际环境变量对膜生物污染的影响。从这些研究中获得的知识将为合理的AnMBR操作和抑制特定生物的处理策略提供信息，并将导致改进的抗污染膜材料的发展。除了这些试验台和中试规模的系统，PSD方法还可用于揭示其他废水处理系统中的微生物组装机制，其中生物污染是一个限制问题。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。

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.