Making waves: Rethinking our mission for N2O emissions at WRRFs

Abstract

Nitrous oxide (N₂O) is a potent greenhouse gas with a global warming potential 273 times that of CO₂, and it is a significant contributor to ozone depletion. Water resource recovery facilities (WRRFs) have been identified as a major source of N₂O emissions, leading to significant research and policy efforts to mitigate these emissions. As WRRFs undertake these N₂O mitigation efforts, important questions remain regarding the impact of more intensive nitrogen removal for pollution prevention and public health protection and how reactive nitrogen discharges are emitted as N₂O in receiving waterways. To answer these questions, this perspective highlights the importance of balancing facility-scale emission factors to estimate N₂O emissions from wastewater while considering the impacts of nitrogen if discharged to receiving water bodies. This perspective suggests more comprehensive approaches to manage N₂O emissions, emphasizing the need to account for the reduction in N₂O emissions achieved through nitrogen removal at WRRFs compared to direct discharge into receiving water bodies. By considering the overall impact of nitrogen from wastewater on N₂O emissions from both WRRFs and receiving water bodies, WRRFs can reduce their impact on the environment while maintaining their important role in removing nitrogen from wastewater.