Understanding process densification and fundamentals of nitrification inhibition in pure oxygen aerated activated sludge systems.

Municipal wastewater treatment plants often use the activated sludge process, which relies on groups of bacteria to remove harmful pollutants from wastewater. These bacteria break down organic matter and ammonia into safer substances, helping protect rivers, lakes, and human health. To keep the bacteria alive and working, air is pumped into the water to provide oxygen. However, this aeration step uses a large amount of energy—about 50–90% of the electricity used in treatment—because oxygen does not transfer efficiently from air into water. This problem becomes even harder when treatment plants try to handle larger water flows or meet stricter cleaning standards. This project will study the use of pure oxygen instead of air to support bacterial growth more efficiently. Researchers will also operate small laboratory reactors to encourage the formation of dense bacterial granules, which can treat wastewater faster. The project will support STEM education by training college students and providing research experiences for undergraduate and K–12 students, while also working with industry partners to apply the results in real systems. There are two major challenges associated with using pure oxygen (pure-Ox) in densified wastewater treatment plants (WWTPs): first, the process kinetics and operational strategies for sludge densification in activated sludge systems using pure-Ox are not well developed, creating a significant knowledge gap; second, activated sludge processes using pure-Ox typically fail to achieve nitrification, the biological oxidation of ammonia to nitrite and nitrate. Efficient nitrogen management is one of the 14 grand challenges identified by the National Academy of Engineering, and WWTPs that discharge into sensitive water bodies are increasingly required to control nitrogen more effectively. This project aims to address both challenges through a set of integrated research objectives, providing new tools for process intensification in space-limited urban treatment plants and improving nitrogen management in existing oxygen-fed systems. The project will pursue three objectives: (1) evaluate the feasibility of sludge densification supported by pure oxygen, (2) investigate the molecular mechanisms responsible for nitrification inhibition using functional gene expression analysis and advanced analytical chemistry under both open and closed reactor configurations, and (3) examine the ecophysiology of microbial communities in flocs, granules, and biofilms, and link microbial structure and function to process performance using ecological theory. The central hypothesis is that sludge intensification through granulation-based densification with pure oxygen can achieve high treatment rates while enabling effective nitrogen removal. Compact, densified granules are expected to protect nitrifying bacteria from low pH and other operational stresses associated with pure-Ox systems, thereby improving overall treatment performance. 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. NSF Award ID: 2602319 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Ramesh Goel | Institution: University of Utah, SALT LAKE CITY, UT | Award Amount: $468,590 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2602319 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2602319.html