Nitrous Oxide Emissions Research

Nitrous Oxide Emissions Testing equipment at the Brightwater Treatment Plant

Nitrous oxide (N2O) is a powerful greenhouse gas that is emitted from biological wastewater treatment processes and especially from those processes which convert or remove nitrogen (e.g. ammonia). However, there are few studies that have continuously measured N2O emissions from full-scale wastewater treatment plants for significant periods.

This project aims to measure nitrogen (N2O) emissions from the biological nitrogen conversion (nitrification) process at the Brightwater Treatment Plant before and after a process improvement project. We also measure N2O from the South Treatment Plant during times when the biological process partially removes nitrogen (summer/fall) and doesn't (winter/spring). In addition, we measure N2O emissions from aerobic granular sludge in a laboratory setting, a novel nitrogen removal technology.

This work will better inform King County and the broader wastewater community on how future nitrogen removal requirements will impact greenhouse gas emissions. The work includes applied research conducted by the University of Washington Department of Civil and Environmental Engineering under the existing Graduate Research Fellowship Program.

Final report HERE