Mitigation of methane emissions in a pilot-scale biocover system at the AV Miljø Landfill, Denmark: 2. Methane oxidation.
Greenhouse gas mitigation at landfills by methane (CH4) oxidation in engineered biocover systems is believed to be a cost effective technology but so far a full quantitative evaluation of the efficiency of the technology in full scale has only been carried out in a few cases. A third generation semi-passive biocover system was constructed at the AV Miljø Landfill, Denmark. The biocover was fed by landfill gas pumped out of three leachate collection wells. An innovative gas distribution system was used to overcome the often observed uneven gas distribution to the active CH4oxidation layer resulting in overloaded areas causing CH4emission hot spot areas in the biocover surface. The whole biocover CH4oxidation efficiency was determined by measuring the CH4inlet load and CH4surface fluxes. In addition, CH4oxidation was determined for single points in the biocover using two different methods; the carbon mass balance method (based on CH4and carbon dioxide (CO2) concentrations in the deeper part of the cover and CH4and CO2surface flux measurements) and a new-developed tracer gas mass balance method (based on CH4and tracer inlet fluxes and CH4and tracer surface flux measurements). Overall, the CH4oxidation efficiency of the whole biocover varied between 81 and 100% and showed that the pilot plant biocover system installed at AV Miljø landfill was very efficient in oxidizing the landfill CH4. The average CH4oxidation rate measured at nine campaigns was approximately 13gm-2d-1. Extrapolating laboratory measured CH4oxidation rates to the field showed that the biocover system had a much larger CH4oxidation potential in comparison to the tested CH4load. The carbon mass balance approach compared reasonably well with the tracer gas mass balance approach when applied for quantification of CH4oxidation in single points at the biofilter giving CH4oxidation efficiencies in the range of 84 to a 100%. CH4oxidation rates where however much higher using the tracer gas balance method giving CH4oxidation rates between 7 and 124gm2d-1compared to the carbon mass balance, which gave CH4oxidation rates -0.06 and 40gm2d-1. The study also revealed that the compost respiration contributed significantly to the measured CO2surface emission, and that the contribution of the compost respiration decreased significantly with time probably due to further maturation of the compost material.
Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Charlotte
C
Scheutz
Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Filippo
F
Cassini
Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark.
Jan
J
De Schoenmaeker
Department of Environmental Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark. Electronic address: pekj@env.dtu.dk.
Peter
P
Kjeldsen
D000393:Air Pollutants / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis; D003718:Denmark; D004784:Environmental Monitoring; D008697:Methane / Q000032:analysis*; D010084:Oxidation-Reduction; D012037:Refuse Disposal / Q000379:methods*; D064091:Waste Disposal Facilities
D000393:Air Pollutants; D002245:Carbon Dioxide; D008697:Methane
Engineered solutions; Greenhouse gas; Mitigation documentation; Waste disposal