Relationship of microbial mass and activity in biodegradation of solid waste

Abstract

Limited landfill space and resistance to siting such facilities has spurred consideration of new approaches to increase the longevity of landfills. Such efforts have included exploring methods to enhance degradation rates of municipal solid waste (MSW) and subsequently, mining landfills to recover materials and landfill space. Microbial mass and activity of MSW incubated in lysimeters, with moisture content sustained with recycled leachate, were compared under anaerobic and aerobic conditions in this study. Bacterial biomass and number were quantified by adenosine triphosphate analysis and acridine orange direct counts. Viability, adenylate energy charge and cellulase activity were also assessed. Bacterial number and energy status were lower in the anaerobic system. Cellulase activity in the anaerobic lysimeter decreased to undetectable levels while activity in the aerobic system continued to increase throughout the 92-day experiment. The results indicated that aeration, even at a relatively low volume, with leachate recirculation, significantly accelerated degradation of MSW. Furthermore, the results demonstrated the potential of using cellulase activity as a surrogate parameter of relative microbial activity of MSW degradation.