Effect of Landfill Time on Physico-Chemical Properties of Combustible Fractions in Excavated Waste

Excavated waste pertains to the substance that is produced subsequent to its deposition in landfills as a consequence of the inherent microbial breakdown and fermentation processes. The implementation of effective management and use of excavated trash offers substantial prospects for environmental protection, resource preservation, and economic growth. Presently, there is a notable emphasis in scholarly investigations on the examination of the physico-chemical characteristics of polyethylene and polypropylene materials included in landfill debris. Nevertheless, there is a notable lack of understanding regarding the alterations in the physico-chemical characteristics of combustible components across varying durations of excavated waste. To investigate the impact of varying durations on the physico-chemical characteristics of waste, researchers conducted an analysis on a sample landfill site located in Tianjin, China, where the maximum age of the dump was 18 years. The findings of the study indicated that the excavated waste that underwent screening had elevated levels of calorific value, ash content, and fixed carbon content in comparison to municipal solid waste. Furthermore, it was noted that the oxygen in the excavated waste exceeded that of municipal solid waste, a phenomenon that might potentially be attributed to the influence of environmental factors present at the landfill site. The main combustible constituents of landfill waste have been identified as polyethylene, polypropylene, expanded polystyrene, polyethylene terephthalate, and wood. Furthermore, it is shown that the mechanical properties of these materials experience a substantial decrease, which may be attributed to alterations occurring inside the carbon chain molecules. Over the course of the landfill process, there is a gradual alteration in the chemical makeup of the combustible components. The aforementioned findings provide valuable theoretical insights into the process of waste excavation for recycling, thereby contributing to the advancement of waste management and reuse techniques.