Implementing Method 25.3 to Measure VOC Emissions from Composting in Washington State

Conducted as part of the Waste to Fuels Technology Partnership 2021–2023 Biennium, this report develops and implements SCAQMD Method 25.3 to measure volatile organic compound (VOC) emissions from composting systems in Washington state. The project established Method 25.3 analytical capability at Washington State University’s Laboratory for Atmospheric Research and evaluated its performance relative to an accredited California laboratory.

Using a two-zone continuously aerated static pile (CASP) pilot system in Pullman, researchers measured VOC mass flux and emission factors under varying aeration conditions. Surface flux chambers, negative aeration duct monitoring, GC-MS canister analysis (EPA TO-15), and proton transfer reaction mass spectrometry (PTR-MS) were employed to characterize compound-specific emissions and total VOC carbon.

Results indicate that VOC emissions from modern forced-aeration systems may be substantially lower than emission factors derived from older windrow composting studies. The findings support improved emission factor development for Washington compost facilities and inform regulatory and permitting considerations under Clean Air Act requirements.