A semi-analytical model for methane transport and oxidation in a soil cover

An analytical model for methane and oxygen transport through a single soil cover considering diffusion, advection, and oxidation was developed. The results obtained by the analytical model agree well with those obtained by the numerical model and the column tests. Dimensionless analysis indicates that methane emission flux is more sensitive to the variation of Pe and Da numbers when advection dominates methane transport (Pe > 1) and oxidation dominants methane transport (Da > 10), respectively. It also indicates that landfill gas pressure build-up will decrease the amount of oxygen migrating into the soil. The methane emission flux for the case with Sr = 0.2 is 5.30 and 200 times greater than the cases with Sr = 0.5 and 0.8, respectively. The methane removal efficiency for the case with Sr = 0.8 is 1.25 and 1.58 times greater than the cases with Sr = 0.5 and 0.2, respectively. With the increase of Sr (soil moisture content), methane oxidation rate increases, and diffusion coefficients and advection rates decrease. The methane removal efficiency was increased because more amount of methane was stuck and oxidized in the soil.

Automated summary

The study demonstrates that gas-solid reactions, oxygen flux, and soil moisture content significantly impact methane emission efficiency during methane transport. Additionally, the effects of advection and oxidation on methane transport are more pronounced when Pe > 1 and Da > 10, respectively.