Wastewater plants emit twice the greenhouse gases, US study finds

A recent Princeton-led study reveals that wastewater treatment plants in the U.S. emit significantly more greenhouse gases—methane and nitrous oxide—than previously estimated by the Environmental Protection Agency (EPA). The researchers found that these facilities produce 2.4 times more methane and 1.9 times more nitrous oxide than EPA calculations, accounting for approximately 2.5% of U.S. methane and 8.1% of nitrous oxide emissions. Given that these gases have contributed to about 22% of global warming since 1850, the study highlights wastewater plants as a more substantial source of climate pollution than recognized. The research team conducted extensive field measurements over 14 months using a mobile lab equipped with advanced sensors, visiting 96 plants that process about 9% of U.S. wastewater. Their findings showed emissions vary widely with environmental conditions such as temperature and rainfall, and that most emissions come from a relatively small number of plants. This suggests targeted interventions could effectively reduce emissions without