Rening av svavelväte och koldioxid i deponigas med slaggrus

Modern landfills produce landfill gas, LFG, on a smaller scale and with limited content of degradable organic materials in the waste. The waste deposit in the Sofielund landfill began in 2005 and the final coverage is not yet commenced. The landfill waste must contain up to 10% decomposable organic materials at most. In a previous experiment on Sofielund landfill in summer 2011, the measurements from four sample wells showed the landfill gas consisted of up to 45% Methane and about 17000 ppm of Hydrogen sulfide, and the rest was only carbon dioxide. During the earlier experiment in 2011 and during 2012 the smell of H2S got offensive periodically and apart from that, concentrations above 1000 ppm are toxic. Previous research, Bottom ash for biogas upgrading, BABIU, shows that bottom ash from municipal solid waste incinerator (MSWI) can effectively reduce CO­­2 and H2S contents of landfill gas. Bottom ash from MSWI can be utilized in upgrading landfill gas and reduce odor problems of landfills with high H2S production. In this study, an area of 15m x 12m was covered with weathered slag from bottom ash with thickness of about 30cm, to examine how this layer can reduce the concentrations of H2S and CO2. Gas samples were taken from depths of 10cm and 15cm below the surface of bottom ash. There were also samples taken from around the slag-covered area. The surface was laid out 5 days before the first measurement was performed. The experiment was carried out for 20 days, 5, 7, 11, 13, 18 and 20 days after establishment of the surface with bottom ash. The intensity of emissions in different parts of the landfill varied from time to time, due to compacting and changing the permeability of the surface, and it shows that LFG flow in the Sofielund is near the lowest limit of it. Considering the results from the tests in 2011 in deep wells, the recent measurements done in this study showed low contents of LFGs. The highest contents of LFGs in the measurements belong to a pipe, which was found in the waste area of the landfill. Those highest contents of LFG were 15.1% methane, 12.1% carbon dioxide, 0.4% oxygen and the hydrogen sulfide did not exceed 2 ppm. This shows that in deeper depths concentrations of LFG is higher than that of the surface and 10cm below the surface. In the slag covered area CO2 content increased day by day from the first day of the measurement to the last day due to carbonation of the slag and its role in CO2 sequestration. According to the recent measurement, it can be suggested to cover the landfill with a layer of slag as a construction material, to minimize the LFG emissions and the bad smell from H2S. Therefore it can eliminate direct emissions of LFG to the atmosphere by diffusion through the slag layer. This diffusion allows adsorption of CO2 and oxidation of H2S