Odor and Odorous Chemical Emissions from Animal Buildings: Part 6. Odor Activity Value

Abstract

There is a growing concern with air and odor emissions from agricultural facilities. A supplementary research project was conducted to complement the U.S. National Air Emissions Monitoring Study (NAEMS). The overall goal of the project was to establish odor and chemical emission factors for animal feeding operations. The study was conducted over a 17-month period at two freestall dairies, one swine sow farm, and one swine finisher facility. Samples from a representative exhaust airstream at each barn were collected in 10 L Tedlar bags and analyzed by trained human panelists using dynamic triangular forced-choice olfactometry. Samples were simultaneously analyzed for 20 odorous compounds (acetic acid, propanoic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, hexanoic acid, heptanoic acid, guaiacol, phenol, 4-methylphenol, 4-ethylphenol, 2-aminoacetophenone, indole, skatole, dimethyl disulfide, diethyl disulfide, dimethyl trisulfide, hydrogen sulfide, and ammonia). In this article, which is part 6 of a six-part series summarizing results of the project, we investigate the correlations between odor concentrations and odor activity value (OAV), defined as the concentration of a single compound divided by the odor threshold for that compound. The specific objectives were to determine which compounds contributed most to the overall odor emanating from swine and dairy buildings, and develop equations for predicting odor concentration based on compound OAVs. Single-compound odor thresholds (SCOT) were statistically summarized and analyzed, and OAVs were calculated for all compounds. Odor concentrations were regressed against OAV values using multivariate regression techniques. Both swine sites had four common compounds with the highest OAVs (ranked high to low: hydrogen sulfide, 4-methylphenol, butyric acid, isovaleric acid). The dairy sites had these same four compounds in common in the top five, and in addition diethyl disulfide was ranked second at one dairy site, while ammonia was ranked third at the other dairy site. Summed OAVs were not a good predictor of odor concentration (R2 = 0.16 to 0.52), underestimating actual odor concentrations by 2 to 3 times. Based on the OAV and regression analyses, we conclude that hydrogen sulfide, 4-methylphenol, isovaleric acid, ammonia, and diethyl disulfide are the most likely contributors to swine odor, while hydrogen sulfide, 4-methyl phenol, butyric acid, and isovaleric acid are the most likely contributors to dairy odors.

Testing odorants recovery from a novel metallized fluorinated ethylene propylene gas sampling bag

“…The large number of animals raised in concentrated animal feeding operations (CAFOs) can affect air quality by emissions of odor, volatile organic compounds (VOCs), NH 3 , H 2 S, greenhouse gases (GHGs), and particulate matter (PM) (National Research Council [NRC], 2003;Heber et al, 2006aHeber et al, , 2006bJacobson et al, 2008;Hoff et al, 2009). Air pollution and odor nuisance are a major challenge for livestock production (NRC, 2003;Kim et al, 2007;Parker et al, 2012;Cai et al, 2015;Zhang et al, 2015). Many researchers develop and test odor mitigation technologies (Akdeniz and Janni, 2012;Chen et al, 2009;Cai et al, 2007).…”

Surface Application of Soybean Peroxidase and Calcium Peroxide for Reducing Odorous VOC Emissions from Swine Manure Slurry

“…The overall importance of 4-ethylphenol emissions is somewhat unknown because of limited information on its odor threshold. A single reference quotes an odor threshold for 4-ethylphenol about 5 higher than the geometric mean threshold for 4-methylphenol (Parker et al, 2012b). At the 4-ethylphenol concentrations observed in this research, 4-ethylphenol accounted for less than 1% of the overall OAV.…”

“…Odor activity values (OAV), defined as the ratio of the concentration of a compound to the human odor detection threshold (ODT) for that compound (Guadagni et al, 1963;Leffingwell and Leffingwell, 1991;Parker et al, 2012b;Zhang et al, 2015), were calculated to assess the relative importance of individual chemical compound reductions (or increases) on odor. Compounds with large OAVs are more likely to contribute to the overall odor of a complex odor mixture.…”

“…Compounds with large OAVs are more likely to contribute to the overall odor of a complex odor mixture. Odor activity values were calculated using the geometric mean odor detection thresholds (ODT) as summarized in the comprehensive review presented in Parker et al (2012b). The relative contribution of each compound was calculated by dividing the OAV for the individual compound by the sum of the OAVs for all compounds (Guadagni et al, 1963;Leffingwell and Leffingwell, 1991).…”

Odor and Odorous Chemical Emissions from Animal Buildings: Part 3. Chemical Emissions

“…Among seven phenolic and indolic compounds, 4-methylphenol was the most abundant compound in the exhaust air at the swine and dairy sites, and its concentrations were well above its odor detection threshold (Devos et al, 1990;Parker et al, 2012). The compound 4-methylphenol has been identified as a key priority odorant inside swine facilities, downwind of beef cattle feedyards, and from land-applied swine manure (Wright et al, 2005;Koziel et al, 2006;Bulliner et al, 2006;Trabue et al, 2008b;Parker et al, 2012). Compared with VFAs and phenolic and indolic compounds, five VSCs were measured at relatively lower concentrations.…”