Characterization of Compost Emissions using Gas-Chromatography Methods

Composting is a growing industry and a more efficient way to decompose different materials. Odorous compounds are constantly emitted from compost and many are classified as volatile organic compounds (VOCs). Air samples were taken at Washington State University Compost Facility to study non-methane hydrocarbons and other VOCs. Air within the compost piles was bubbled through an impinger to collect water and water-soluble VOCs and subsequently into a thermal desorption tube to collect water insoluble VOCs. Samples were then returned to the laboratory for analysis of over 100 VOCs using headspace-gas chromatography with flame ionization detection (HS-GC-FID) for water samples and thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) for air samples. During the summer, higher levels of isoprene ranging up to 600 ppb and dimethyl sulfide up to 200 ppb in air samples were seen. Acetone was prevalent in the water samples ranging up to 770 ppb. The water samples effectively captured alcohols since they were not present in the air samples. Air toxics and odorous VOCs will be summarized seasonally and temporally.