Biofilters Used to Reduce Emissions from Livestock Housing – A Literature Review

R.E. Nicolai and R.M. Lefers South Dakota State University, Brookings, South Dakota Abstract This paper reviews the literature on the development of biofilters for use on confined livestock facilities. More specifically the paper addresses the history, current and accepted design parameters, and status of research. Biofilters offer one potential solution to reduce nuisance odors and pollutants emitted from confined livestock housing. Typical biofilters used in agriculture consist of an organic media mixture of wood chips and compost. Barn exhaust air is blown through this media, allowing the microorganisms contained within the media to break down the gaseous compounds. Biofilters have been used in agriculture in Europe since the 1970’s and in the United States since the 1990’s. Much advancement has been made in terms of biofilter design since their introduction to agriculture. Design parameters have been established to minimize cost and maximize effectiveness. Some of these design parameters include bed thickness, media type, empty bed contact time, moisture control, and media bed orientation. These design parameters also influence factors such as pressure drop, microbial ecology, air channeling, foot print size, and gas/odor removal efficiency. Overall, properly designed biofilters used in agriculture have been shown to reduce hydrogen sulfide emissions by up to 95% and ammonia emissions by up to 65%. Biofilters are an effective air pollution control option for agriculture.