The aim of this paper was to apply and validate a model for measuring the rate and extent of anaerobic digestion, composting and CH4 oxidation in laboratory scale beds. Degradation studies were performed in four reactors each packed with shredded unsorted municipal solid waste, with one bed covered with a 100 mm layer of soil. The rates of production of CH4, CO2, 13C-CO2 and the rate of consumption of O2 were measured and used as inputs to a mass balance expressions for these components to calculate the rates of anaerobic digestion, composting and CH4 oxidation. The results showed that anaerobic digestion, composting and CH4 oxidation occurred simultaneously in both the covered and uncovered beds. The analysis showed that 50 ± 4% of the solids (COD basis) in the uncovered beds degraded anaerobically, with the generated CH4 subsequently oxidized, and that 32 ± 4% of the solids degraded aerobically in the covered bed.
Keywords: Aerobic processes; Carbon stable isotope; Composting; Landfill; Mass balance model; Methane oxidation.
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