SEQUENTIAL BATCH ANAEROBIC COMPOSTING OF MUNICIPAL SOLID-WASTE (MSW) AND YARD WASTE

Sequential batch anaerobic composting (SEBAC(TM)) was used to treat two fractions of municipal solid waste (MSW), the organic fraction of the MSW (processed MSW) and yard waste. Processed MSW gave a mean methane yield of 0.19 m3 kg-1 volatile solids (VS) (range = 0.18-0.22) after 42 days. The mean VS reduction was 49.7% (range = 46.6-52.4) for this same period. Yard waste gave a mean methane yield of 0.07 m3 kg-1 VS (range 0.05 - 0.09). Methane content of the biogas stabilized at a mean of 48% (SD = 11) from three to four days after startup. The mean VS reduction for yard waste was 19% (range = 13-24). With processed MSW the volatile acid concentration was over 3000 mg L-1 during startup but these acids were reduced within a few days to negligible levels. The trend was similar with yard waste except that volatile acids reached maximum concentrations of less than 1000 mg L-1. Composts from the reactors were evaluated for agronomic characteristics and pollution potential. Processed MSW and yard waste residues had marginal fertilizer value but posed no potential for groundwater pollution. Yard waste residue caused no apparent inhibition to mustard (Brassica juncea) germination relative to a commercial growth medium. Anaerobic yard waste compost demonstrated the potential to improve the water holding capacity of Florida soils.