A comparative assessment of ammonia emissions from water-holding structures at swine facilities with different technologies for animal waste treatment

Currently, animal waste on swine farms in the United States is managed utilizing the conventional lagoon and spray technology (LST). In response to the increasing concerns about the adverse environmental impacts of concentrated swine farms in some areas, such as the eastern North Carolina, a number of potential environmentally-superior technologies (ESTs) have recently been developed and evaluated as alternative technologies for treatment of animal waste. Although evaluations of potential ESTs under the project OPEN (Odor, Pathogens, and Emissions of Nitrogen)included odor and pathogens also, this comparative assessment will be focused particularly on the nitrogen-ammonia (NH3-N) emissions from water-holding structures at swine facilities with several different ESTs. Emissions of NH3-N at ESTs are compared with the projected emissions from waste treatment lagoons at two LST farms, under similar environmental conditions, using an observational-statistical model.

This assessment is based on the extensive field measurements of ammonia flux, lagoon temperature, pH, and other lagoon parameters, as well as meteorological parameters, during two intensive observational periods, representing warm and cold seasons, at each of the LST and EST swine facilities. Estimated emissions of NH3-N from water-holding strucures at an EST or LST farm were normalized to the live animal weight and the nitrogen excretion rate (E) based on the animal feed analysis at the farm. Normalized emissions (%E) were used to determine the percentage reduction, if any, in the emission of NH3-N by each EST from that of the LST. Only a few of the evaluated ESTs are found to be effective in substantially reducing ammonia emissions in both seasons.