Simulação do fluxo vertical de contaminantes em liners de aterros sanitários utilizando diferentes isotermas de sorção

Abstract

Improper disposal of municipal solid waste can cause significant negative environmental impacts, particularly on soil and groundwater, since the leachate generated during waste degradation is highly toxic. Among the pollutants present in this effluent are heavy metals, such as chromium (Cr), used in industrial processes and found in electronic materials. This study focused on the base layer (liner), a structure responsible for preventing the percolation of contaminants into the subsoil and aquifers, considering an operating sanitary landfill in the Brazilian semiarid region. Therefore, the study simulated the vertical transport of Cr through different layers of liner soil, evaluating the contaminant's behavior from the perspective of the linear adsorption isotherm and Langmuir. The simulations were performed in Hydrus-1D, based on experimental data from the mixture of natural soils with different proportions of bentonite soil (5SB and 20SB). Hydraulic parameters and water retention characteristics were adjusted based on laboratory tests and numerical models, considering a 15-year climate scenario for water flow and a 30-year climate scenario for contaminant transport. As a result, an estimated annual leachate formation of 32.85 cm/year was estimated, and chromium infiltration exceeded a depth of 170 cm in the natural soil. Mixtures with a higher bentonite soil content, such as 20SB, performed better in containing the contaminant, proving more effective in mitigating Cr percolation, especially when combined with the Langmuir isotherm, which demonstrated greater retention capacity.