The effects of aged refuse and sewage sludge on landfill CH4 oxidation and N2O emissions: Roles of moisture content and temperature

A laboratory-scale experiment was conducted to investigate the effects of mix ratio, moisture content and temperature on the methane oxidation potential (MOP) through a landfill bio-cover of aged refuse and sewage sludge. The CH4 oxidation rate increased considerably when the moisture content and temperature increased from 18% to 30% by mass and 4 to 35 °C, respectively. In order to produce the maximum MOP, the optimum conditions for the bio-cover system were as follows: an aged refuse:sewage sludge ratio of 6:4, a moisture content of 30% and an incubation temperature of 35 °C. After distilled water addition, N2O emissions from the bio-cover with an aged refuse:aged sludge ratio of 6:4 was 10.2 times higher than the clay soil cover (p > 0.05). Compared to the global warming burden caused by CH4 emissions, the increase in the N2O and CO2 emissions from a bio-cover of aged refuse and sewage sludge could be ignored in terms of overall MSW landfill emissions. Due to its high tolerance for environmental variation and the savings in land resources, the mixture of aged refuse and sewage sludge is a good option for mitigating CH4 emission when applied to municipal solid waste landfill.