Odor and odorous chemical emissions from animal buildings: Part 6.Odor activity value

Authors: Parker, David; KOZIEL, JACEK - Iowa State University; CAI, LINNGSHUANG - Iowa State University; JACOBSON, LARRY - University Of Minnesota; AKDENIZ, NESLIHAN - University Of Minnesota; BEREZNICKI, SARAH - Purdue University; LIM, TENG-TEEH - University Of Minnesota; CARAWAY, EDWARD - West Texas A & M University; ZHANG, SHICHENG - Fudan University; HOFF, STEVE - Iowa State University; HEBER, ALBERT - Purdue University; HEATHCOTE, KATIE - Iowa State University; HETCHLER, BRIAN - University Of Minnesota

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2012
Publication Date: 12/10/2012
Citation: Parker, D.B., Koziel, J.A., Cai, L., Jacobson, L.D., Akdeniz, N., Bereznicki, S.D., Lim, T., Caraway, E.A., Zhang, S., Hoff, S.J., Heber, A.J., Heathcote, K.Y., Hetchler, B.P. 2012. Odor and odorous chemical emissions from animal buildings: Part 6.Odor activity value. Transactions of the ASABE. 55(6):2357-2368.

Interpretive Summary: A research project was conducted to quantify odor and odorous chemical emissions from animal feeding operations. The study was conducted over a 17-month period at two free stall dairies, one swine sow farm, and one swine finisher facility. Air samples were collected from the exhaust fans of the buildings and analyzed for odor and the individual chemicals responsible for odor. Air samples were collected in plastic bags and analyzed for odor concentration by eight human panelists. Odorous chemicals were collected in small-diameter tubes filled with sorbent and analyzed with analytical instruments. In this paper, which is part of a six-paper series summarizing results of the project, we investigate the relationship between odor concentration and odor activity value (OAV). The OAV is defined as the chemical 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 individual chemical compound OAVs. Of the 20 odorous chemicals that were analyzed, we determined that hydrogen sulfide, 4-methylphenol, isovaleric acid, ammonia, and diethyl disulfide were the most likely contributors to swine odor, while hydrogen sulfide, 4-methyl phenol, butyric acid, and isovaleric acid were the most likely contributors to dairy odor.

Technical 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 free stall dairies, one swine sow farm, and one swine finisher facility. Samples from a representative exhaust air stream 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, p-cresol, 4-ethylphenol, 2-aminoacetophenone, indole, skatole, dimethyl disulfide, diethyl disulfide, dimethyl trisulfide, hydrogen sulfide, and ammonia). In this paper, which is part of a six-paper 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 threshold (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.