CAREER: Quorum enhanced sustainable treatment of nitrogen (QuEST-N)

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).Environmental engineers have used microorganisms over a century to treat wastewater and protect public health. Biological wastewater treatment (WWT) also plays a critical role in ecosystem and environmental protection including the use of nitrifying and denitrifying bacteria to remove and convert excess nitrogen from wastewater to harmless nitrogen (N2) gas. Advances in environmental metagenomics are providing more detailed and in-depth information about microbial communities in WWT systems. Yet, environmental engineers and wastewater practitioners lack strategies and tools to leverage this new information to control the structure, composition, functional diversity, and metabolic pathways of nitrifying and denitrifying bacterial communities in WWT systems. The overarching goal of this CAREER proposal is to harness various forms of microbial communication signals, commonly referred to as quorum sensing (QS) molecules, to advance the design and operations of more efficient and sustainable biofilm reactors for nitrogen removal. The successful completion of this project will benefit society through the generation of new fundamental knowledge to advance the development and implementation of next generation biological nitrogen removal (BNR) processes in wastewater treatment plants (WWTPs) and water resource recovery facilities (WRRFs). Further benefits to society will be achieved through student education and training including the mentoring of a post-doctoral fellow, a graduate student, and three undergraduate students at Howard University.Advances in environmental microbiology, microbial ecology, and environmental biotechnology are providing unprecedented opportunities to design and build next generation biofilm reactors for the simultaneous removal of excess nutrients (nitrogen and phosphorus) from wastewater. Biofilm reactors are enabling WWTPs and WRRFs to harness slow growing microorganisms that are advantageous to BNR processes including anaerobic ammonium oxidizers (anammox) and denitrifying anaerobic methane oxidizers (DAMO). However, the design and operation of next generation biofilm reactors for BNR will require the control of the biofilm microbial ecology to achieve more efficient and cost-effective nitrogen removal from wastewater. The overarching goal of this CAREER project is to explore the use of quorum sensing (QS) to control and manipulate the microbial ecology of bacterial biofilms used in BNR reactors. QS involves the generation and release of signaling molecules known as autoinducers that enable bacterial communities to coordinate their behavior including the formation of biofilms. The guiding hypotheses of this research are that the presence of autoinducers changes the activity of nitrogen cycling bacteria and QS can be used to alter which organisms colonize a biofilm. The specific objectives of the proposed research are to: (1) Test the effect of autoinducers in cultures enriched for nitrogen cycling bacteria; (2) Evaluate the effect of autoinducers in nitrogen cycling bacteria in more complex biofilm communities; (3) Develop a biofilm model that incorporates QS; and (4) Evaluate a control strategy that uses autoinducer molecules in a membrane aerated biofilm reactor. The successful completion of this project has the potential for transformative impact through the generation of fundamental knowledge to advance the development and deployment of the new process of quorum enhanced sustainable treatment of nitrogen (QuEST-N) within WWTPs and WRRFs. To achieve the educational and training goals of this CAREER project, the Principal Investigator will leverage her ongoing collaboration with the Water Environment Federation (WEF) to 1) add a research training component to the InFLOW (Increasing Opportunities in Water) program at Howard University and 2) expand the program to other minority serving institutions (MSI) to advance diversity in STEM education and broaden participation in the water industry workforce.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.