Effect of Waste Composition and Load Application on the Biodegradation of Municipal Solid Waste in Bioreactor Landfills

摘要

Intensive research has focused on the biodegradation of the typical municipal solid waste in bioreactor landfills, but relatively little attention has been given to the biodegradability of individual refuse components. The objective of this paper is to examine and compare the degree of biodegradation of different waste fractions, textile, paper, and mixed waste, through measuring the change in the physical properties and settlement characteristics of waste and leachate quality, in six bench-scale bioreactor landfills operated under anaerobic conditions. Also, the impact caused by waste density increase in the form of subsequent waste layers on the same bioreactors is investigated. Two groups of bench-scale anaerobic bioreactor landfills operated for 125 days. The first group was designed to study the anaerobic biodegradability, leachate quality, change in physical properties, and settlement of textile, paper, and mixed waste. The second group operated with the addition of 40 kg of load per cell to represent the overburden stresses provided by subsequent layers of waste. Mixed cells achieved about four times total wet weight reduction more than textile cells and about three times total wet weight reduction more than paper cells. Chemical oxygen demand, biological oxygen demand, volatile fatty acids, and total solids concentrations exhibited a classical peak in paper and mixed bioreactors followed by an asymptotic decline. Mixed waste experienced the highest settlement (27.2%) compared to paper and textile waste, which exhibited a maximum settlement of about 9.0%. Significant difference in the waste settlement between Group 1 (no load application) and Group 2 (load application and higher waste density) was noted. However, increasing waste density had a small effect on the leachate quality and the physical properties of waste.