ABSTRACT
Tree buffers are a potential low cost sustainable odor mitigation strategy used by animal feeding operations; however, there is little to no data on their effectiveness. This study was designed to evaluate how tree buffers affect air flow patterns at a swine facility and measure their effectiveness in controlling odor from the facility. Wind tunnel experiments were used to determine the effect buffers had on wind flow patterns within the facility. Odor mitigation analysis measure both particulate matter and vapor phase odorants before and after tree buffer. Particle concentrations were measured with optical particle counters (OPC) and odorous compound concentrations were measured using sorbent tubes with thermal desorption (TDS) GC-MS analysis. Both particle filters and plant material from tree buffers were analyzed for sorption of odorous compounds with TDS-GC-MS analysis. The wind tunnel experiments indicated that the effect of both buildings and trees on wind velocity and turbulence would potentially enhance trapping of odorous material by slowing wind velocity and increasing mixing near trees. For particulates, tree buffers reduced concentrations by 44% when winds came from the south (main buffer ran east-west on the north side of the facility). Most particles were classified in the smaller size fraction (0.30-0.49 μm); however, the tree buffers removed the larger size particles more effectively than smaller size fraction. The buffer removed volatile fatty acids (VFAs) in the air stream by over 50%, while aromatic odorants were not as easily removed with the summer sampling showing little to no difference in terms of concentrations of these compounds and Fall sampling showing reduced levels. Odorants sorbed to both particulate filters and plant material also support this finding in that VFA were significantly higher than odorous aromatic compounds. Plant material taken from trees in the buffer showed significantly
higher loadings of odorous VFAs, phenolic, and indole compounds for samples taken from 8 ft compared to samples taken from either 2 or 4 ft.
