Characterization of Volatile Organic Compound (VOC) Emissions from Swine Manure Biogas Digestate Storage

Livestock manure is one of the major sources of volatile organic compound (VOC) emissions; however, characteristics of VOCs emitted from biogas digestate (BD) storage, which is a common manure practice, remain unclear. The objective of this study was to characterize VOC emissions during BD storage through the dynamic emission vessel method, to identify the VOC emissions that have potential odor and/or toxic effects. The results revealed the detection of 49 VOCs with seven classes, whose total concentration varied from 171.35 to 523.71 μg m−3. The key classes of the 49 VOCs included Oxygenated VOCs (OVOCs), olefins and halogenated hydrocarbons. The top four compositions, accounting for 74.38% of total VOCs (TVOCs), included ethanol, propylene, acetone and 2-butanone. The top four odorous VOCs, accounting for only 5.15% of the TVOCs, were toluene, carbon disulfide, ethyl acetate and methyl sulfide, with the concentration ranging from 13.25 to 18.06 μg m−3. Finally, 11 main hazardous air pollutant VOCs, accounting for 32.77% of the TVOCs, were propylene, 2-butanone, toluene, methyl methacrylate, etc., with the concentration ranging from 81.05 to 116.96 μg m−3. Results could contribute to filling the knowledge gaps in the characteristics of VOC emissions from biogas digestate (BD), and provide a basis for exploring mitigation strategies on odor and hazardous air pollutions.