Investigation of the Biological Activity and the Environmental Impact of Tunisian MSW Landfills

This paper presents the results of the investigation of the biological activity that takes place in three municipal solid waste landfills (MSW landfills) situated in different regions of two dry climate in Tunisia. Since the climatic water balance is negative (potential evapotranspiration being 1.5 to 5 times higher than rainfall), it has often been considered that this kind of landfill has neither environmental impact nor efficient biological activity. However, the three landfills revealed a biological activity with biogas often containing more than 60 percent of methane. Indeed, the upper waste layer that was effectively dry (dry weight from 85 to 98%), the core of refuse contained between 35 and 65% of dry matter. In some boreholes, the produced gases periodically expelled leachates like small geysers. Therefore, the results assess that landfill management in countries with dry climate should be considered with adapted technologies, not necessary the same as under temperate or humid climates.