Monitoring of Biogas from Two Covers of Lysimeters Filled with Municipal Solid Waste

Abstract

In Brazil, conventional covers of sanitary landfill are consisted of fine soils compacted with tractor treadmill. Nonetheless, some clays have swelling behavior and present shrinkage cracking when they are dry, impairing their performance with relation to control the flow of water into the waste mass and the flow of gases out of the waste mass. This control is necessary to minimize the leachate and gas volume generated into de waste mass. This research aimed to evaluate the performance of two conventional covers of two lysimeters filled with municipal solid waste (MSW) of Campinas city, Brazil. For this, the concentration of gases (CO₂ and CH₄) that was coming out of covers was obtained using flux chamber and correlate with the concentration of gases that were drained by central pipe. Disturbed soil samples from two covers were characterized by geotechnical tests such as grain-size distribution, consistent limits, unit weight and moisture content. Permeability testes were also performed with specimens trimmed of undisturbed soil samples collected of two covers. The soil samples were classified as silt clayed-sandy and they presented micro aggregation. Saturated permeability coefficients presented orders of magnitude of 10⁻⁴ and 10⁻⁵ cm/s. Gas concentrations from central drain were greater than gas concentrations from the cover, twice for CO₂ and 30% for CH₄, approximately. The precipitation influenced the gas concentrations from central drain and from covers differently and this fact is discussed.