Degradation and Stabilization Degree of Municipal Solid Waste: The Case of Two Landfills in China

The relationship between the cellulose/lignin (C/L) ratio and degradation rate of municipal solid waste (MSW) in landfills remains unclear. In this study, the USA National Renewable Energy Laboratory (NREL) method was employed to determine the cellulose and lignin contents of MSW at different stages of aging. A normalized degradation-stabilization index (β) that represents the ratio of C/L change to the initial C/L value was introduced to characterize the degradation and stabilization degree of solid waste, aiming to provide a scientific basis for the sustainable management of landfills. We made the following observations: (1) Over time, the degradation rate of organic matter in MSW slows down and stabilizes. This process is crucial for predicting the long-term environmental impact of landfills and formulating resource recovery strategies, contributing to the sustainable management of landfills. (2) The degradation rates of lignin and cellulose change from fast to slow over time, and the relationship between the C/L ratio and landfill age can be described effectively by the exp-decay formula. Understanding this relationship helps to optimize the waste decomposition process, reduce the negative environmental impact of landfills, and promote the sustainable development of landfills. (3) During the aging process of the landfill, the degree of waste degradation and stabilization initially increases rapidly and then shows a gradually decreasing trend. The relationship between the landfill stabilization degree, landfill age, and degradation rate can be represented adequately by a logistic formula. We also obtained expressions showing the correlations among landfill degradation–stabilization degree, age, and organic matter content. The findings provide valuable insights into landfill capacity, operational lifespan, and the redevelopment of landfills for MSW disposal, all of which are essential aspects for the sustainable management of landfills.