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Goali: A New Strategy For Biofouling Control Of Water Filtration Membranes Using D-Amino Acids


<p>Biofouling remains the biggest barrier to application of membrane technology in water and wastewater treatment despite intensive research in the past decades. Inspired by the recent discovery that D-amino acids (D-AAs) commonly produced by bacteria can trigger bioiflm disassembly at very low concentrations, the researchers propose a university-industry collaborative project to develop a novel, highly effective and environmentally friendly approach to biofouling control in membrane systems using D-AAs. The main objective of the proposed research is to assess the potential of and develop strategies for using D-AAs to control biofouling in wastewater treatment membrane systems. Their central hypothesis is that D-AAs are common interspecies signal compounds used by different bacteria to mediate biofilm disassembly; careful manipulation of this regulation process can prevent biofilmformation and remove preformed biofilms. The long term goal of our collaboration is to develop and commercialize a highly effective, environmentally benign membrane cleaning method for biofouling control in membrane bioreactors (MBR) and reverse osmosis (RO) systems. They will first screen all 19 D-AAs individually and in combinations for their individual and synergistic effects on biofilm-formation and disassembly of model bacterial single cultures as well as mixed cultures from conventional activated sludge and MBR. Using well characterized model bacteria, they will investigate the key mechanisms involved by probing bacterial responses to D-AAs in cell growth, peptidoglycan synthesis, surface proteins and lipopolysaccharides, and relating them to cell-cell and cellsurface adhesion as well as biofilm structural integrity. The potential of bacteria developing resistance over long term exposure will also be investigated and corresponding mitigation strategies evaluated. Information obtained from these fundamental researches will be used to develop practical biofouling control strategies, which will be tested in laboratory membrane units, a small scale MBR-RO system, and a pilot MBR system. The proposed study explores a new paradigm of membrane biofouling control based on a recent scientific discovery. It will determine the commonality in bacteria?s use of D-AAs as interspecies signals for biofilm mediation and provide a mechanistic understanding of the process at the cellular level. This will not only advance our knowledge in biofilm formation and regulation, but also open a window of opportunity for developing biofouling control strategies utilizing this specific signal pathway. It is the first study to systematically examine all 19 D-AAs, the first to assess the impact of DAAs on multi-species biofilms, the first to investigate the connection between D-AA induced cell physiological changes and biofilms formation/ disassembly, and the first to seek engineering application of this new science. Industry participation makes it possible to test the biofouling control methods using realistic conditions and at pilot scale, facilitating industry application of the scientific research. From the fundamental aspect, the project contributes to our understanding of chemical signal pathways used by bacteria to regulate biofilms, which has great impact on many scientific fields including microbiology, biochemistry, environmental, biomedical, and chemical engineering. From the application point of view, D-AA or D-AA analogue based biofilm control strategies could be used in a large number of environmental, biomedical and industrial systems, e.g., sensors, medical implants, water/wastewater treatment and distribution systems, cooling towers and food processing equipment, to prevent detrimental impact of biofilms. The university-industry collaboration provides a much needed bridge from fundamental research to technology development and implementation. The education and research activities proposed will enrich our undergraduate and graduate curricula through a new lab module and guest lectures, and provide research training to graduate and undergraduate students with special effort in recruiting women and minority students. Students will be involved in industry R&D to take the state-of-the-art academic research directly to industrial technology development, work closely with practitioners on real engineering systems, and learn effective communication across disciplines. The PI and the industry co-PI will also jointly provide educational experiences to high school teachers and environmental engineers.</p>

Li, Qilin; Liu, Charles
Rice University
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