Variations of the Physical and Chemical Characteristics of Sanitary Landfill Leachate after Percolation into Tropical Soils

Tropical soils are common in Brazil and present very peculiar geotechnical properties, such as fine particle aggregation; natural cementation; and high porosity, which often turn away from the classical models of the Soil Mechanics. Due to this, they are now the focus of recent studies for use as alternative materials for several applications in geotechnical site. This research studies two tropical soils from the Southeastern Brazil to evaluate the variations of the physical and chemical characteristics of sanitary landfill leachate after percolation into these soils. Soil samples were submitted to geotechnical, physical, chemical and mineralogical tests. After these tests, soil samples were compacted with 3 % above their optimum moisture content and placed in polyvinyl chloride columns. The leachate was collected from a regional sanitary landfill and characterized by physical and chemical tests with relation to volatile fatty acid (VFA), chemical oxygen demand (COD), pH, alkalinity, and metals (Cr, Mn, Fe, Co, Ni, Cu, Zn and Pb), before and after percolation into the soils by means of column tests. Curves of concentration versus percolation time for COD, VFA, and metals were obtained for the two soils. COD concentration increased with percolation time for the two soils, while the adsorption/desorption behaviours were different for the two soil, mainly for VFA, Pb, Ni and Co.