Considerations on the methane correction factor and fraction of methane parameters in the IPCC first-order decay...

Understanding the behavior of organic carbon in municipal solid waste landfills is a major challenge for estimating methane (CH₄) emissions using the Intergovernmental Panel on Climate Change (IPCC) first-order decay (FOD) model. According to the IPCC guidelines, the default values of CH₄ correction factor (MCF) and fraction of CH₄ (F) for active aeration landfills are set as 0.4 and 0.5, respectively. However, whether it is reasonable to apply the default values of MCF and F to active aeration landfills is questionable. This study aims to estimate the MCF and develop a method to determine the F value for active aeration landfills. In this investigation, three landfill sites were operated as active aeration landfills to estimate the MCF and the F. The study results indicate that MCF values were lower than the default value of 0.4 provided in the IPCC guidelines under aerobic conditions with a CH₄ concentration of less than 5%. According to the carbon balance analyses, there was a mismatch between the theoretical CH₄/CO₂ ratio based on the F default value of 0.5 and the measured CH₄/CO₂ ratio. Using the F calculation method proposed in this study, the theoretical CH₄/CO₂ ratio and the measured CH₄/CO₂ ratio was calculated equally. The F values during air injection ranged from 0.25 to 0.93 at three landfill sites, suggesting that adapting the F default value of 0.5 for active aeration landfills may lead to significant errors in the estimation of CH₄ emissions using the IPCC FOD model.