Evaluating Draft EPA Swine Emission Models – Part II: Open-Source Manure Storage

Highlights Draft EPA emission models for swine open-source manure storage were systematically evaluated. Draft EPA models performed poorly on estimating pollutant emissions when input variables were beyond NAEMS data. An unanticipated sensitivity of the draft EPA model outputs to climate was identified. Draft EPA models may need further revision and improvement before being adopted by the swine industry. ABSTRACT. In August 2021, the United States (U.S.) Environmental Protection Agency (EPA) released draft models to estimate daily NH 3 and H 2 S emissions from open-source swine manure storages (swine facilities are evaluated in Part I of this series), that is, breeding/gestation lagoons, and grow-finish lagoons and storage basins using inputs of daily mean ambient temperature and wind speed. These models were developed by the EPA using refined datasets generated by the National Air Emissions Monitoring Study fieldwork completed in 2009. This paper evaluated the robustness of the EPA draft models using a “one-factor-at-a-time” sensitivity analysis. Also, annual emission estimates were calculated using inputs reflective of typical U.S. swine housing practices and ambient conditions of representative swine producing regions in the U.S. Draft model outputs predicted NH 3 emissions from lagoons to be greater than values reported in the current literature, depending on ambient temperature and magnitude of wind speed. The draft models predicted significantly greater NH 3 emissions from storage basins than those reported in the current literature. These current draft emission models cannot be used to accurately characterize the wide range of swine open-source manure storages where management across regions varies considerably. Revisions are suggested to accommodate a greater range of climates and scale for practical emission estimations. While these models may provide some insight into estimating emissions, they may not fully encapsulate the complexity and variability of emissions from swine open-source manure storages. Keywords: Air quality, Ammonia, Basin, Hydrogen sulfide, Lagoon, Pigs, Slurry.