Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 22, 2010
Publication Date: March 1, 2011
Citation: Parker, D.B. 2011. Effectiveness of a manure scraper system for odor control in tunnel-ventilated swine finisher barns. Transactions of the ASABE. 54(1):315-324. Interpretive Summary: Odor can be a concern to residents living downwind of swine farms. A research project was conducted to compare odor emissions from traditional flush barns to those with automated scrapers. The study was conducted at commercial tunnel-ventilated swine barns in northwest Missouri. Odor samples were collected from the barn exhaust in plastic bags and analyzed by trained human panelists. In addition, the individual compounds responsible for the odor were analyzed and reported. Average odor concentrations in the barn exhaust were 75.6 percent lower in scraper barns than flush barns. Total reduced sulfur concentrations were 89.9 percent lower in scraper barns than flush barns. Odor was 1.65 times higher during the flushing period, an indication that the recycled flush water contributes considerably to the overall odor emissions. These results show that converting from a flush system to a scraper system is a practical alternative for odor control in tunnel-ventilated swine barns.
Technical Abstract: Options for odor control from tunnel-ventilated swine barns are limited. Automated scrapers have been successful for reducing odor emissions in free-stall dairies, and for reducing H2S emissions in research-scale swine finisher rooms, but their effectiveness for reducing odor in commercial tunnel-ventilated swine barns has never been evaluated. A research project was conducted to compare odor emissions from traditional flush barns to those with automated scrapers. The study was conducted at commercial tunnel-ventilated swine barns owned by Premium Standard Farms LLC in northwest Missouri. Odor samples were collected from the barn exhaust in Tedlar bags and analyzed by trained human panelists using triangular forced-choice olfactometry. Total reduced sulfur (TRS) concentrations were measured with a portable Jerome meter, and volatile organic compounds (VOCs) were sampled in sorbent tubes and analyzed by gas chromatography/mass spectrometry. Mean odor concentrations (dilutions to threshold, DT) were 75.6 percent lower in exhaust from scraper barns (DT=941) than flush barns (DT=3860) (p<0.001). Mean recognition thresholds (RT) were 76.4 percent lower in exhaust from scraper barns (RT=494) than flush barns (RT=2095) (p<0.001). TRS concentrations averaged 1.59 and 0.16 ppm in flush and scraper barns, respectively (p=0.029). Hedonic tone and intensity were statistically similar for flush and scraper barns. Odor was positively correlated with TRS in flush barns, while in scraper barns odor was positively correlated with butyric acid, 4-ethylphenol, indole, and skatole. Odor concentrations were significantly greater during flush events than between flush events (p=0.002), but there was no difference between mean odor concentrations during or between scrape events (p=0.20). These results show that scraper barns are a practical alternative for odor control in tunnel-ventilated swine barns.