A novel time-series-based kinetic model for degradation of municipal solid waste under different oxygen concentrations

Aeration is pivotal in accelerating landfill stabilization. Biodegradation kinetic models of landfills have not fully accounted for the uneven distribution of oxygen during aerobic in situ stabilization, owing to the high heterogeneity of landfills. In this study, a successive degradation of organic matter (SDOM) model is proposed to calculate the reaction rate constant of municipal solid waste (MSW). The SDOM model assumes that organic matter (OM) is composed of n independent shares, with each share starting to degrade at different times. However, all fractions degrade according to first-order kinetics once they enter the reaction phase. In this study, degradation tests of typical organic matter in landfills were conducted under varying oxygen concentrations, and the reaction rates for each degradation test were calculated using the SDOM model. Subsequently, a model was developed to simulate the variation in the reaction rate constant with the oxygen concentration. Superposition tests on multiple types of organic matter were conducted to further validate the superposition principle of the degradation process. Model verification using real waste data revealed a reaction rate constant of 0.12, demonstrating a better fit compared to the Monod model and traditional first-order kinetic model, as well as the highest accuracy in the calculation of CO₂ produced in the degradation process. The SDOM model can help to understand the degradation mechanism of the aerobic in situ stabilization of landfills in a better manner.