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

Methane (CH 4 ) 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 CH 4 emissions from a closed landfill located at Kudjape, Saaremaa Island, Estonia. This investigation documented the alteration in the emission of CH 4, 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. CH 4 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 CH 4 concentration took place over time; b) hot-spot with an extremely high concentration of CH 4 albeit consistent decrease over the years; c) a location with minimal initial concentration of CH 4. Multivariate analysis showed that the CH 4 concentration dynamics and parameters reflecting the CH 4 oxidation process activity were different in biocover across the landfill. Based on data analysis results, the CH 4 oxidation process stabilizes in biocover in 5–6 years after establishing the cover.