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Abstract. Recently, bioreactors, such as biotrickling filters, have been used to reduce odor and gas emissions from livestock facilities. Considerable efforts have already been made over the years to evaluate and improve the efficiencies of bioreactors used for this purpose; however, no study has yet been published that attempts to provide a thorough assessment of the performance of bioreactors in eliminating most (if not all) of the gases exhausted from swine facilities. Thus, this study was conducted to obtain a better understanding of the performance of biotrickling filters in treating swine odors by conducting a comprehensive evaluation of their overall performance in removing odor and gaseous components. Evaluating the performance of biotrickling filters using persistent gaseous components, i.e., those that remain in the treated air and contribute to the malodor, helps identify areas of the treatment system that can still be potentially improved. The gaseous components monitored were ammonia (NH3), hydrogen sulfide (H2S), and volatile organic compounds (VOCs). Samples were collected from two four-week trials using three laboratory-scale pig chamber and biotrickling filter systems. The NH3 and H2S concentrations were measured using non-dispersive infrared and ultraviolet fluorescence analyzers, respectively, while VOCs were collected using adsorption tubes and analyzed by a gas chromatograph coupled with a mass spectrometer and an olfactory detection port (GC-MS-O). Samples for odor measurement were also collected and analyzed using a dynamic olfactometer. Linear regression and odor index were used to identify the odorants that had the largest odor impacts. Odor index is an integrated parameter that expresses the combined contributions of odor intensity and hedonic tone to the perceived odor. Of the 176 VOCs identified in the samples, the odor components that had the largest odor impacts included butanoic acid, 3-methylbutanoic acid, 2-methylbutanoic acid, 2-methylpropionic acid, pentanoic acid, p-cresol, 2,3-butanedione, and dimethyl sulfide. However, most of these substances were almost completely eliminated in the biotrickling filters, except p-cresol and dimethyl sulfide. This implies that optimizing the removal of poorly water-soluble components, such as p-cresol and dimethyl sulfide, could further improve the performance of biotrickling filters in treating swine odors. Keywords: Biotrickling filters, Removal efficiency, Swine odor components.

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Numerous residents in agricultural areas are concerned about the impact that the swine industry may have on the ambient air quality. They assume there is a risk because there is limited information on the airborne contaminant that may originate from these facilities. The objective of the project was to assess the impact of swine production on ambient air quality related to public health in farming communities. Of the six chosen communities, three were considered not to be in a swine production area, whereas the three others were considered to be within a swine production area. Data were collected during three periods in spring and summer 2006. Ammonia and hydrogen sulfide concentrations were monitored on a continuous basis whereas odor concentrations and intensities were monitored twice a week. Odor concentrations were measured by dynamic olfactometry and odor intensities were determined by trained odor assessors. Public health was evaluated by survey questionnaires sent to a sample of residents in each of the six communities. Average NH(3) concentrations ranged from 6.9 to 12.6 ppb for nonexposed communities and from 8.9 to 18.3 ppb for exposed communities. Average H(2)S concentrations ranged from 1.1 to 1.5 ppb for nonexposed communities and from 1.1 to 1.6 ppb for exposed communities. For a community in a swine production area, ambient NH(3) and H(2)S concentrations were found to be higher than those communities not in a swine production area; however, that difference was not significant and they were within air quality standards for public health and safety. Odor concentrations showed no significant difference between the nonexposed and exposed communities and between evening and morning periods. Odor intensities were found to be significantly higher in the communities within swine production areas. More research will be required to fully understand the correlation between specific physical symptoms from residents and the presence of odors from swine production.

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