Characterization of Odorants From Products of 14 Different Commercial Composts Using Solid Phase Microextraction

Abstract

In this study, headspace odorants from market-ready, commercial composts supplied by 14 different producers were characterized with a recently developed analytical method using solid phase microextraction (SPME). The products analyzed were derived from a cross-section of the wide array of compost feedstock ingredients used in the U.S., e.g., biosolids, yard trimmings, animal manure, and industrial by-products. A variety of quality assessment tests were performed using test procedures specified in a national certification program offered through the U.S. Composting Council. Measurements of odorous chemicals, i.e., trimethylamine, carbon disulfide, dimethylsulfide, dimethyldisulfide, propionic acid, and butyric acid, supplemented other quality aspects in the evaluation of stability. From the results, relatively higher levels of sulfur compounds were detected from marketable composts containing sewage sludge than from composts produced with other feedstocks. The greatest amounts of reduced sulfur compounds were produced from a compost containing an industrial sludge and agricultural byproducts. Pathogen indicator microbes for most composts were within limits for Class A (USEPA 40CFR Part503). Very large numbers of fecal coliforms, E. coli, and Enterococcus were present in the compost that produced the greatest concentrations of carbon disulfide and dimethylsulfide. Compost containing biosolids and yard wastes produced relatively higher level of propionic and butyric acids than those containing other ingredients. Odorant analysis of final products can be readily evaluated with the SPME method reported here. Results in combination with other compost quality factors may help compost producers and users improve product quality.