Sludge Watch ==> Sludge Composts more 'odiferous'...higher pathogens

[Maureen Reilly]

CHARACTERIZATION OF ODORANTS FROM PRODUCTS OF 14 DIFFERENT COMMERCIAL 
COMPOSTS USING SOLID PHASE MICROEXTRACTION

Published by the American Society of Agricultural and Biological Engineers, 
St. Joseph, Michigan www.asabe.org

Citation:  Pp. 026-033 in Air Pollution from Agricultural Operations III, 
Proceedings of the 12-15 October 2003 Conference (Research Triangle Park, 
North Carolina USA), Publication Date 12 October 2003.  701P1403.
Authors:   H. Kim, L. L. McConnell, P. Millner

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.