Estimation of methane emission by a municipal landfill: the case of Palermo

CH4 diffuse emissions from municipal solid waste landfills represent one of the most important anthropogenic source of greenhouse-gas. CH4 is produced by anaerobic biodegradation of organic matter in land-filled MSW and it constitutes the major component of landfill gas. Gas recovery is a suitable tool to effectively control CH4 emissions from landfill sites and the quantification of CH4 emissions represents a good tool to evaluate the effectiveness of biogas recovering system in reducing biogas emission. In particular, LFG emissions can be indirectly evaluated from mass balance equations between formation, recovery and oxidation of biogas in the landfill, as well as on a direct approach based on LFG emission measurement from landfill surface. However, up to now few direct measurements of landfill CH4 diffuse emissions have been executed. In the present study, both methodologies have been applied to the case study of Palermo (IT) landfill (Bellolampo). The main aim of the study was to evaluate CH4 diffuse emissions based on direct measurements carried out with the accumulation chamber method. Such emissions have been compared with the estimate achieved by means of mass balance equations. The obtained results showed a good reliability of the proposed methodology, and that the evaluated contoured flux maps represent a reliable tool to locate areas with abnormal emissions in order to optimize the gas recovering system efficiency.