Modification and application of methane oxidation capacity in-situ testing methodology in MSW landfill cover layer

To expand the applicability of the in-situ landfill layer CH₄ oxidation capability analysis method, the carbon conservation method based on the ratio of CO₂ and CH₄ was optimized. The optimized method was then applied on Asuwei landfill site located in Beijing for analysis of the variation rule of landfill layer CH₄ oxidation capability. The results showed that CO₂ and CH₄ flux ratios on the cover layer surface were higher in summer than that in winter, and relatively stable in autumn and winter. Both the CH₄ oxidation velocities and oxidation ratios of cover layer in autumn and winter were far lower than that in spring and summer. In addition, the average CH₄ oxidation velocity (by carbon) in monitoring zone Ⅰ was 1 569.89 mg/(m ²·h) in spring and summer, and 171.13 mg/(m ²·h) in autumn and winter, while in monitoring zone Ⅱ the average velocity was 1 054.47 mg/(m ²·h) in spring and summer, and 333.02 mg/(m ²·h) in autumn and winter. The average CH₄ oxidation ratio in monitoring zone Ⅰ was 79.69% in spring and summer, and 7.54% in autumn and winter, while in monitoring zone Ⅱ that was 44.83% in spring and summer, and 11.33% in autumn and winter. The annually averaged CH₄ oxidation capacity in monitoring zone Ⅰ with longer landfilling time was 911.7 mg/(m ²·h), greater than that in in monitoring zone Ⅰ 〔707.5 mg/(m ²·h)〕.The results of CH₄ oxidation velocities and oxidation ratios of cover layer had a good coherence with the existing related studies, and this method should have a better applicability for the estimation of the CH₄ oxidation capability in the landfill layer.