title: Reduction of volatile fatty acids and odor offensiveness by anaerobic digestion and solid separation of dairy manure during manure storage.
abstract: Volatile fatty acids (VFA) play an important role in the biodegradation of organic wastes and production of bioenergy under anaerobic digestion, and are related to malodors. However, little is known about the dynamics of VFA during dairy manure storage. This study evaluated the characteristics of VFA in dairy manure before and after anaerobic co-digestion in a laboratory experiment using eight lab-scale reactors. The reactors were loaded with four different types of dairy manure: (1) liquid dairy manure from a freestall barn, (2) mixture of dairy manure and co-digestion food processing wastes at the inlet of an anaerobic digester, (3) effluent from the digester outlet, and (4) the liquid fraction of effluent from a solid separator. Four VFA (acetic, propionic, butyric, and 2-methylbutyric acids) were identified and quantified in weekly manure samples from all reactors. Results showed that the dominant VFA was acetic acid in all four manure sources. The off-farm co-digestion wastes significantly increased the total VFA concentrations and the proportions of individual VFA in the influent. The dairy manure under storage demonstrated high temporal and spatial variations in pH and VFA concentrations. Anaerobic digestion reduced the total VFA by 86%-96%; but solid-liquid separation did not demonstrate a significant reduction in total VFA in this study. Using VFA as an indicator, anaerobic digestion exhibited an effective reduction of dairy manure odor offensiveness.
authors.affiliation: Department of Agricultural and Biological Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907, USA.
authors.forename: Laura H
authors.initials: LH
authors.lastname: Page
authors.affiliation: Department of Agricultural and Biological Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907, USA. Electronic address: jiqin@purdue.edu.
authors.forename: Ji-Qin
authors.initials: JQ
authors.lastname: Ni
authors.affiliation: Department of Agricultural and Biological Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Department of Agricultural and Biological Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907, USA.
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Heber
authors.affiliation: Department of Agricultural and Biological Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907, USA.
authors.forename: Nathan S
authors.initials: NS
authors.lastname: Mosier
authors.affiliation: Department of Agricultural and Biological Engineering, Purdue University, 225 S. University Street, West Lafayette, IN 47907, USA.
authors.forename: Xingya
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Biological Systems Engineering, Washington State University, PO Box 646120, Pullman, WA 98935, USA.
authors.forename: Hung-Soo
authors.initials: HS
authors.lastname: Joo
authors.affiliation: Department of Biological Systems Engineering, Washington State University, PO Box 646120, Pullman, WA 98935, USA.
authors.forename: Pius M
authors.initials: PM
authors.lastname: Ndegwa
authors.affiliation: Department of Animal Sciences, Washington State University, Research and Extension Center, 2606 West Pioneer, Pulyallup, WA 98371, USA.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Harrison
mesh_terms: D000397:Air Pollution / Q000517:prevention & control*; D000693:Anaerobiosis; D000818:Animals; D001673:Biodegradation, Environmental; D019149:Bioreactors; D002417:Cattle; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D008372:Manure / Q000032:analysis* / Q000145:classification; D009812:Odorants / Q000517:prevention & control*
chemical_list: D005232:Fatty Acids, Volatile; D008372:Manure
keywords: Animal agriculture; Malodor; Manure management; Waste treatment; pH