Municipal solid waste landfill performance with different biogas collection practices: Biogas and leachate generations

This study investigated the performance of simulated landfills with different biogas collection practices, including upward biogas collection only (LT) and both upward and downward biogas collection (LTB). A simulated landfill was constructed using a stainless steel lysimeter equipped with a compression unit. Upward gas flow was favored in uncompressed MSW when both upward and downward gas flows were allowed (LTB). By reducing void ratio, the preferential flow direction of biogas was changed to downward gas flow along with gravimetric leachate drainage. In LT, porched leachate was formed because high flow resistance by countercurrent gas-liquid flow affected moisture redistribution. It was considered that high pressure buildup in gas-filled pores of LT enhanced uneven moisture distribution and resulted in inhibiting methane production. The cumulative methane volume produced from LTB was 2.5 times as much as that of LT.