Assessment of the Bacteriological Quality of Compost from a Yard Waste Processing Facility

Abstract

Citizen concern over possible pathogenic microorganism contamination in compost and in a runoff collection pond prompted a U.S. Environmental Protection Agency (EPA) investigation. One out of eight samples collected from the distribution pile at a yard waste compost processing facility in Knoxville, Tennessee, was found to have 2.3 × 103 MPN/g fecal coliform, no Escherichia coli (E. coli) were detected. All other distribution pile samples proved to be negative for fecal coliform. The geometric mean of the eight samples was found to be less than 38 MPN/g, well below the 1,000 MPN/g limit for land application of class A municipal sludges treated by an acceptable composting process. Samples obtained from the processing pile area before and after shredding had an average fecal coliform density of greater than 5.0 × 105 MPNig, and an average E. coli density of 6.0 × 104 or 7.4 × 104 MPN/g depending upon the analytical technique used. The origin of these microorganisms was not determined, though it appears unli...