Presentazione di una metodologia per il monitoraggio del flusso diffuso di biogas dal suolo delle discariche

Since 1998 more than 15 Municipal Solid Waste (MSW) landfill sites have been monitoring by means of accumulation chamber method, through spot measurements of CO2 and CH 4 flux from soil. The obtained data in a grid have been processed by geostatistical and statistical procedures to determine the total diffuse biogas flux from soil and its spatial distribution. In the present paper we report a case study from the Legoli landfill (Pisa). The drawn isoflux maps identified anomalous degassing zones where it is possible to operate for reducing biogas emission (i.e. amount of pollutant substances that can be responsible for health damage and the greenhouse effect). Estimation of the total output of diffuse biogas from soil correlates fairly well with the difference between the theoretical amount of biogas yielded by the landfill, obtained by mathematical production models, and the actual total biogas burnt in the plant to produce electric power. This methodology allows obtaining useful information for the optimum management conditions in time for the exploitation of the biogas.