Molecular-approach Diagnosis of Green gases Emission from landfill sites of Municipal Solid Wastes

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In the present study, we analyzed 1) initial degradation process of organic organic fraction of municipal solid wastes (OFMSW) in the laboratory-scale vertical column, which simulates landfill site soil layers, 2) structure and diversity of the microbial communities of landfill site soil. Four simulated landfill columns were prepared with different conditions with respect to oxygen and water availability. A significant extent of OFMSW degradation occurred during rather earlier stage of 150 days, corresponding to acid-producing phase. During the following period organic degradation becomes less and less with time elapsed, corresponding to methane-producing phase. Based on these observation, we proposed the way of landfill site operation, so as to 1) enhance aerobic condition at the upper portion of landfill site, and 2) recirculate the leachate liquid. Methane production yield was highest in bottom of the columns (e.g., anaerobic part) while it was lowest in surface of the columns (e.g., aerobic part). Thus result suggested that net methane production in the site should be subtracted by methane oxidizing bacteria. Contribution of the each column parts to global warming was evaluated, based on the gas generation data during the first year, and the result showed that contribution of semi aerobic part was much higher compared with that of aerobic site in which significant amount of carbon dioxide was produced.This result suggested that net methane production in the landfill sites should be subtracted. by methane oxidizing' bacteria. Contribution of the each column parts to global warming was evaluated, based on the gas generation data during the first year, and the result showed that contribution of semi aerobic part was much higher compared with that of aerobic part in which significant amount of carbon dioxide was produced.