klimazwei - MiMethox

MiMethox – Microbial Oxidation of Methane in Landfill Top Covers

In Europe, 30 % of the anthropogenic methane emissions are estimated to originate from landfills, constituting the second largest source. On older sites, the energetic utilization or flaring of landfill methane often is no longer possible or viable, due to the lessened gas production rate. These residual emissions, however, which continue for several decades after landfill closure, still hold significant safety and environmental risks and should thus be treated.

The microbial oxidation of methane in biofilters or cover soils is considered an effective option for the treatment of landfill emissions that do not meet the calorific requirements for energetic utilization or flaring. Although the potential of engineered landfill covers for the successful mitigation of methane emissions has been recognized in a number of studies, technical guidelines on how to design these covers and assess their performance are still missing. The overriding aim of the joint research project MiMethox is therefore to develop cover designs specifically suited for the sustainable reduction of methane fluxes from landfills generating low calorific gas and thus to contribute to the National Climate Protection Programme. By developing and validating a method for balancing the methane budget of whole landfills, the prerequisite for the participation of landfill operators in carbon credit trading shall be established. To this end, a comprehensive investigation concept was developed by the project partners, integrating methods from the fields of waste management, modelling, microbiology, soil and atmospheric sciences (see figure).

MiMethox

The scope of the biological mitigation of landfill methane emissions in engineered landfill top covers ranges from landfills in the initial phase of operation, old landfills, the complementation of forced in-situ aeration measures to sites containing material of low gas generation rate. The latter will become increasingly relevant in Europe with the EC landfill directive (1999/31) having come into effect, stipulating that only material of low biological activity may be deposited.