Investigation of the biological activity in MSW landfills under dry climates (Tunisia and Haiti)

This paper presents the results of the investigations carried out over two years (April 2000 – February 2002) to quantify the biological activity that develops in four municipal solid waste landfills located in different regions of two dry climate countries i.e. Haiti and 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, after five campaigns of sampling and analysis at different seasons, the results of the investigations show a relatively stable biological activity in the four landfills with biogas often containing more than 60 percent of methane. Indeed, under 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 assert that landfill management in countries with dry climate should be considered with adapted technologies, not necessary the same as under temperate or humid climates.