Mitigation of methane emissions from three Danish landfills using different biocover systems

The establishment of biocover systems is an emerging methodology in reducing methane (CH4) emissions from landfills. This study investigated the performance of three biocover systems with different designs (biowindow and passively and actively loaded biofilters) in mitigating CH4 emissions from three landfills in Denmark. A series of field tests were carried out to evaluate the functionality of each system, and total CH4 emissions from relevant landfill sections or the entire landfill were measured before and after biocover implementation. Surface CH4 concentration screening and local CH4 fluxes showed generally low emissions from the biowindow/biofilters (mostly < 5 g CH4 m(-2) d(-1)), although some hotspots were identified on two actively loaded biofilters. One passively loaded biofilter exhibited high CH4 emissions, mainly due to gas overloading into the system. Gas concentration profiles measured at different locations suggested uneven gas distribution in the biofilters, and significant CH4 oxidation occurred in both the gas distribution layer (when oxygen was fed into the system) and the CH4 oxidation layer. High CH(4 )oxidation efficiencies of above 95% were found in all systems except for one biofilter (55%). Whole-site emission measurements showed CH4 reduction efficiencies between 29 and 72% after implementing biocover systems at the three landfills, suggesting that they were efficient in reducing CH4 emissions. The most challenging task for the passively loaded biocover systems was to control gas flow and secure homogenous gas distribution, while for actively loaded biocovers, it might be more important to eliminate emission hotspots for better functionality.

Automated summary

This study investigated the performance of three different biocover systems in reducing methane emissions from landfills in Denmark. The results showed that the biocover systems were efficient in reducing CH4 emissions, although there were challenges in controlling gas flow and ensuring homogeneous gas distribution.