Enumeration of Anaerobic Refuse-Decomposing Micro-Organisms On Refuse Constituents

Hydrolytic, acetogenic and methanogenic bacteria are required for the conversion of refuse to methane in landfills. In order to identify sources of these trophic groups in refuse, the total anaerobic population and the sub-populations of cellulolytic, hemicellulolytic, butyrate catabolizing acetogenic, and acetate- and H 2 -CO 2 -utilizing methanogenic bacteria as present on grass, leaves, branches, food waste, whole refuse and two landfill cover soils were enumerated by the most probable number (MPN) technique. Total anaerobes ranged from 10 3 cells per dry gram in cover soil to 10 9 in grass, food waste and fresh refuse. Hemicellulolytics ranged from 160 cells per dry gram in cover soil to 10 9 in grass. The highest cellulolytic population was measured on branches (316 cells per dry gram), while the maximum acetogenic population was measured on leaves (2.5 x 10 4 ). The highest methanogen populations were measured on leaves (6.3 x 10 3 ) and one of two fresh refuse samples (10 5 ). Yard waste was the major carrier of the trophic groups required for refuse decomposition, while the cover soils tested did not represent major inputs of the requisite bacteria to landfills. © 1996 ISWA