COLLABORATIVE RESEARCH: Virus removal in membrane bioreactors: Role of virus aggregation and adhesion

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1236672/1236393Nguyen/Tarabara Aerobic membrane bioreactors (MBRs) have become a state-of-the-art technology for municipal and industrial wastewater treatment. Compared to traditional activated sludge reactors, advantages of MBR include smaller footprint and better effluent quality. MBRs have become a particularly attractive treatment choice for water reuse. In reuse applications or when the effluent is released to sensitive water bodies such as recreational water, it is especially important that viral pathogens are removed so that public health is not threatened. Comprehensive studies of virus fate in MBRs are currently lacking yet required for wider application of MBR technology, including decentralized water reuse with variable influent quality. The PIs will systematically investigate the role of virus adhesion and aggregation on virus removal in MBRs. The central hypothesis is that the extent of virus adhesion to extracellular polymeric substances (EPS) and soluble microbial products (SMP) counter-correlates with virus passage through the membrane. The experimental plan consists of the following tasks: (1) conduct bench-scale aerobic MBR studies with flat sheet and hollow fiber membranes of varied pore size; in a subset of tests operating conditions will mimic those used in the CH2M Hill full-scale MBR facility in Traverse City, MI, (2) characterize SMP, EPS, and membrane biofilm harvested from the bench-scale MBR system and the full-scale MBR plant, (3) quantify virus aggregation and adhesion to fouled membranes using SMP and EPS characterized in Task 2, (4) correlate adhesion and aggregation with the removal of virus by fouled membranes at different stages of biofilm development, and (5) evaluate virus removal in MBRs using cell culture-dependent methods and quantitative PCR. Adenovirus is selected as target virus for this study. The findings will have the potential for transforming MBR design criteria particularly as they pertain to membrane selection. While MBR-based treatment relies on the membrane to ensure an appropriate separation barrier, virus removal has not been a criterion in designing MBRs. As our technological, economic and social attitudes and approaches toward water shift from the unidirectional resource-to-waste approach toward the concept of sustainable reuse, stricter control over microbiological quality of treated used water becomes a question of when rather than if. With this in mind, we see the practical end of the research we propose in informing the decision-making process reqiered for the development of water reuse policies and regulations of the near future. Successful completion of this project will provide scientific basis for re-conceptualizing MBR design and operation to accommodate virus removal as one of design criteria and treatment goals. The project brings together a diverse team of PIs with a complimentary set of skills including interfacial science, membrane processes, and environmental microbiology and an industrial partner representing a full-scale MBR facility. A group of graduate and undergraduate students co-advised by all PIs will be provided a range of learning opportunities in an environment that combines academic studies, laboratory research in collaboration with the industrial sector, and international work. We will organize annual mini-symposia - at UIUC (year 1), MSU (year 2), and at the Traverse City MBR facility (year 3) where project participants will present their findings, discuss future research and receive feedback from the industrial partner.