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Field Tests of Biofilters in Reducing Aerial Pollutant Emissions from Commercial Finishing Barn

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2011 Louisville, Kentucky, August 7-10, 2011  1111336.(doi:10.13031/2013.37792)
Authors:   Teng-Teeh Lim, Yaomin Jin, Ji-Qin Ni, Albert J Heber
Keywords:   Mitigation, ammonia, hydrogen sulfide, particulate matter, methane, pig

Two elevated-bed, wood-chip biofilters were tested at a commercial swine finishing farm in Indiana, for effectiveness in mitigating aerial pollutant emissions. Large wooden sampling chambers were installed to contain and redirect the biofilter-treated and untreated exhaust streams. Two trials were conducted to test the effects of biofilter thickness, which included 127-mm and 254-mm of media depths. The two biofilters with 127-mm media thickness reduced concentrations of NH3 by 31.2% (p<0.05) and 18.1% (p>0.05), and H2S by 26.6% (p<0.05) and 23.6% (p<0.05) in the pit fan exhaust air, respectively. Insignificant reductions of CH4 concentrations were observed. The biofilters with 254-mm media thickness significantly (p<0.05) reduced concentrations of NH3 by 45.8% (p<0.05) and 18.0% (p<0.05), and H2S by 42.2% (p<0.05) and 27.9% (p<0.05), respectively. Significant reductions of PM10, and TSP were 62.0% and 89.7% for the 127-mm biofilters, and 62.9% and 96.3%, for the 254-mm biofilters, respectively. Very low inlet PM2.5 concentrations were detected. Pressure drops of the biofilters ranged from 29.6 to 57.2 Pa. The empty bed residence times (EBRTs) were 0.3 s and 0.6 s for the 127-mm and 254-mm biofilters, respectively, when the additional pressure drop was considered. Frequent maintenance checks to minimize compaction and ensure uniform moisture content, were required to ensure minimal pressure drops and maximal removal efficiency. The biofilters were relatively simple and inexpensive to install. Although the EBRT was relatively short, they exhibited low to medium mitigation effectiveness. Higher reductions would be obtained with greater media volumes.

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