Landfill CH4 Oxidation, N2O, and CO2 Emissions from Wastewater-Incubated Mineralised Refuse: The Effect of Heavy Metal Addition and Environmental Factor Variations

The first investigations on anthropogenic methane (CH4) oxidation and nitrous oxide (N2O) emissions from mineralised refuse after wastewater treatment are reported. The maximum methane oxidation rate (MOR) in the incubated material was 15.48 μmol/g dry weight/h, which was substantially higher than those for the original mineralised refuse or soil. A correlation analysis (P > 0.05) showed that the mean particle size (D50) value, organic matter content, NH4+–N nitrification, and NO3−–N generation rates (P < 0.05) were highly positively correlated with the MOR for each of the three materials. The addition of heavy metals (i.e., Pb, Zn, Cr, and Cd) resulted in a 20 % decrease in MOR relative to the unamended control for both the incubated mineralised refuse (P < 0.05) and the original mineralised refuse (P < 0.05), and the MOR for soil decreased by 2.5 times relative to the control (P > 0.05). Following the addition of distilled water, N2O emissions from the incubated mineralised refuse were almost two times and 1 order of magnitude greater than those of the MOR (P > 0.05) and soil (P > 0.05). The stimulation of N2O emissions from the mineralised refuse could be neglected under the much higher MOR of a municipal solid waste landfill. Because of its high tolerance for environmental factor variations (i.e., soil temperature and water content) and heavy metal addition, mineralised refuse could be used to filter a wide variety of wastewaters to increase the MOR.