Quantification and modelling of methane and carbon dioxide surface emissions from a South African landfill†

Abstract

Landfill gas (LFG) emissions, primarily CH₄ and CO₂, result from decomposing organic waste in landfills. South Africa faces challenges in managing LFG emissions and effectively handling landfill sites. For this study, a static flux chamber was used to sample CH₄ and CO₂ emissions. The study showed that CH₄ emissions in the capped area had a concentration of 360 819.80 mg m⁻³, with an average emission rate of 433.00 g per m² per day, resulting in 6363.43 Mg per year during the wet season. The active area was observed to have emitted the highest CH₄ concentration (419 863 mg m⁻³) when compared to other areas of the landfill. The lowest CH₄ concentration (45 922.52 mg m⁻³) was emitted from the virgin area. From the virgin area, an average emission rate of 55.11 g per m² per day, resulting in 605.72 Mg per year, was recorded. Similar results based on the sample area variations were also observed during the dry season. Specifically, the active and capped sample area experienced higher CH₄ emissions than the leachate and virgin sample areas. Furthermore, it was observed that the concentrations and emission rates of LFGs emitted during the dry season were lower when compared to the wet season. Similarly, the concentration of CO₂ emissions was higher during the wet season than during the dry season. Enhanced control methods are recommended to improve LFG management practices, especially during the wet season when emissions are higher. Highlighting seasonal variability in emissions underscores the need for targeted strategies to mitigate environmental and health risks. Quantifying LFG emissions from the Thohoyandou landfill in this study sheds light on the environmental and health risks involved. The data presented are crucial for improving landfill management practices in South Africa and for validating the LandGEM model with field-measured and laboratory-analyzed data.