Greenhouse Gas Abatement Potential of U.S. Municipal Water and Wastewater Treatment

Producing drinking water and treating municipal wastewater generate greenhouse gasses (GHGs) that contribute to climate change. Carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are emitted directly by these facilities (Scope 1), especially through biological treatment processes, and indirectly as a result of electricity usage and natural gas combustion (Scope 2). At water treatment plants, energy consumption is the dominant source of emissions but in wastewater treatment facilities, direct process emissions can make substantial contributions to emissions depending on the technologies being used. Current methods of accounting for these emissions often neglect the impacts of CO2 emissions by assuming they are all biogenic, though fossil-based carbon can be an important contributor. Accounting for all sources of GHGs associated with water and wastewater treatment is critical for identifying cost-effective ways to decarbonize this sector. We will present a bottom-up accounting of the scope 1 and 2 GHGs from the water and wastewater treatment sectors, including biogenic emissions. We will also discuss promising strategies for reducing the GHG impacts associated with water and wastewater treatment in the U.S.