Material dependence of methane production rates in landfills

Abstract

An extensive sampling programme has been conducted in six test cells since 1989. The test cells are located at the Spillepeng landfill in the City of Malmo in southern Sweden. Each test cell received a specific waste composition. The main objective of the project was to evaluate the dependence of biogas production on landfill waste composition. Methane production rates in test cells with high amounts of commer cial waste were found to be between 14.3 and 19.0 m3 tonne-1 dry weight yr-1. In test cells with domestic waste or other putrescibles-rich waste fractions the corresponding values were 10.7 to 13.4 m3 tonne-1 dry weight yr-1. In the evalua tion, information regarding density, time of filling, moisture content, temperature, concentration of volatile fatty acids, pH, ammonium and gas extraction, were compared with methane production rates. The main conclusion was that a waste mixture with a high amount of readily biodegradable material gives rise to a high internal concentration of volatile fatty acids, which in turn inhibits the methane production rate.