Performance of biocover in controlling methane emissions from landfill: A decade of full-scale investigation

Methane (CH4) emissions generated from waste management facilities represent a serious global warming concern. The objective of this study was to monitor a fully instrumented biocover capable of abating fugitive CH4 emissions from a closed landfill located at Kudjape, Saaremaa Island, Estonia. This investigation documented the alteration in the emission of CH4, carbon dioxide, and temperature fluctuation for a monitoring period of 10 years after the implementation of biocover. The fine fraction reclaimed from landfill mining along with natural mineral soil and sewage sludge compost in a proportion of 3:1:1 was used as a biocover substrate. CH4 emissions were monitored at the surface and from three locations at a regular depth of 25 cm up to 2 m inside the biocover layer. The measurements recorded from three gas monitoring wells present different scenarios of a typical landfill due to the heterogenous nature of waste and non-homogeneous distribution of landfill gas load to the methane-oxidation layer, namely, a) desired situation where a permanent reduction in CH4 concentration took place over time; b) hot-spot with an extremely high concentration of CH4 albeit consistent decrease over the years; c) a location with minimal initial concentration of CH4. Multivariate analysis showed that the CH4 concentration dynamics and parameters reflecting the CH4 oxidation process activity were different in biocover across the landfill. Based on data analysis results, the CH4 oxidation process stabilizes in biocover in 5–6 years after establishing the cover.