Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/16/2008
Publication Date: 11/1/2008
Citation: Ro, K.S., Mcconnell, L.L., Johnson, M.H., Hunt, P.G., Parker, D. 2008. Livestock air treatment using PVA-coated powdered activated carbon biofilter. Applied Engineering in Agriculture. 24(6):791-798. Interpretive Summary: Reducing ammonia emission from livestock facilities is an important issue for many communities and livestock producers. In addition, ammonia and hydrogen sulfide may adversely affect the health of animals and humans. Biofiltration technology uses both natural and synthetic filter media to provide the surface for the attachment of microorganisms that can remove these air-borne contaminants. Natural filter media such as compost, soil, peat, and woodchips have been frequently used in biofiltration technology. Although costs are low, the natural filter media will decompose, settle, and compact with time. Specially designed synthetic media may overcome these structural limitations of the natural filter media. The objective of this study was to evaluate the efficacy of a synthetic biofilter medium, powered activated carbon particles coated with polyvinyl alcohol gel (PVA), for removing ammonia and hydrogen sulfide from livestock facilities. The PVA biofilters required significantly lower energy to push the air through the biofilter than widely used compost biofilters. The PVA biofilters produced small quantities of a greenhouse gas nitrous oxide; however, they removed most of ammonia (80%) and hydrogen sulfide (97%).
Technical Abstract: Ideal biofilter media provide surface for attachment of microorganisms responsible for removing air-born contaminants while facilitating passage of air. This study evaluated the efficacy of polyvinyl alcohol (PVA)-coated powdered activated carbon particles as a biofiltration medium. This material exhibited excellent properties as a biofiltration medium with a water holding capacity of 1.39 g H2O/g-dry PVA; wet porosity of 0.53; and significantly lower pressure drop than that of commonly reported biofilter media such as compost. Bench-scale biofilters treating off-gas by aerating flushed swine manure samples were used to evaluate ammonia and hydrogen sulfide removal capacities along with greenhouse gas production potentials. Although ammonia adsorption capacity was much lower than granular activated carbon, the PVA biofilter medium retained its ammonia removal capacity because of biological nitrification. The PVA biofilters continued to remove 80% of ammonia in the air for the entire 37 days of operation. While the biofilters produced 0.14 g N2O-N/L-wet PVA, another greenhouse gas methane production was negligible. Hydrogen sulfide was effectively removed (97%) by the PVA biofilters.