Numerical modeling of methane oxidation and emission from landfill cover soil coupling water-heat-gas transfer: Effects of meteorological factors

Abstract

CH4 emissions from landfills present temporal and spatial variation due to the changing meteorological conditions. The combined effect of meteorological parameter on CH4 transport, oxidation and emission are not fully understood. In this study a water-heat-gas transfer model embedding a meteorological module and CH4 oxidation was built to elucidate the CH4 transport, oxidation and emissions in landfill cover soils. A series of parametric studies are carried out to investigate the influence of barometric pressure, air temperature and rainfall on CH4 transport, oxidation and emissions in landfill cover soil. Finally, a real-time climatic condition was conducted to predict the daily CH4 oxidation and emissions from different climatic zones. The simulated results indicated that a low atmospheric pressure would convert the dominant gas transport mechanism from diffusion to advection and therefore result in a lower CH4 oxidation efficiency. In a landfill, the cover soil would also have a higher CH4 oxidation capacity because of the heat conduction from the waste layer under cold conditions. A significant decrease of CH4 emission flux was observed during the rainfall. After rainfall event, the CH4 emission flux was significantly positively correlated with rain intensity. This study proved that building a real-time landfill CH4 emission model considering varying climatic conditions is necessary to improve the accuracy of model predicting.