Biogenic Emissions From Green Waste And Comparison to the Emissions Resulting From Composting (Part 1: Ammonia)

Abstract

The composting process emits various volatile chemicals, including ammonia, that have raised concerns for ambient air quality leading to the regulation of composting facilities. Such regulations often ignored the fact that the feedstocks for composting are natural materials that undergo biological breakdown whether composted or handled otherwise. Consequently, these natural materials are generating ammonia emissions of a biogenic source. It is important to distinguish the biogenic source of ammonia emissions from the anthropogenic contribution to ammonia emissions when these materials are processed in a composting facility. The purpose of the study presented here is to determine the cumulative biogenic ammonia emissions resulting from the natural decay of organic materials, and to compare the emissions to those resulting from composting of the same organic materials. The cumulative emissions of biogenic degradation for 99 days from grass clippings, prunings, and woodchips were determined to be up to 13,705±272.6, 14.35±0.67, and 4.46±1.36 mg NH3-N/kg-dry basis, respectively. The composting of blends of the same feedstock — grass, prunings and woodchips has resulted in emissions that were only 1 to 3% of those expected by natural decomposition. The reduction was 68.6 percent when only prunings were composted without blending with other feedstock or addition of moisture. The results of this study clearly suggest that composting green waste reduces ammonia emissions compared to natural decay.