Biodegradation of methane and halocarbons in simulated landfill biocover systems containing compost materials
The attenuation potential of methane (CH4) and of selected volatile organic compounds (VOCs) was compared in four types of compost materials using dynamic flow column experiments over a period of 255 d. Garden waste compost mixed with wood chips showed the highest steady-state CH4 oxidation rate (161 g m–2 d–1), followed by a commercial compost product Supermuld (110 g m–2 d–1). In the column containing the highest fraction of compost (compost/sand mixed in 1:1), CH4 oxidation declined significantly during the period of operation, probably due to clogging by formation of exopolymeric substances. After 40 d of operation, CH4 production was observed. All the VOCs tested were degraded. CFC-11 (CCl3F) and HCFC-21 (CCl2FH) were anaerobically degraded by reductive dechlorination, generating HCFC-31 (CClFH2) and HFC-41 (CFH3), which were both aerobically degraded in the oxic portion of the columns. Overall, the highest removal of VOCs was observed in the column containing the compost/wood chip mixture. This study demonstrates that biocovers consisting of compost materials have the potential to attenuate trace gas emissions from landfills.