Evolução da dispersão de cobre em liners de aterro sanitário: modelagem como ferramenta de avaliação ambiental

Abstract

The sustainable management of municipal solid waste is one of the main environmental challenges today, particularly concerning soil contamination by heavy metals. The advancement of industrialization and population growth has intensified environmental impacts, making it necessary to adopt effective solutions in civil engineering to mitigate these effects. This study aims to analyze soil contamination by heavy metals resulting from the decomposition of municipal solid waste, with a focus on copper contamination. The research is justified by the need to understand the interaction mechanisms between heavy metals and soil, as well as the impacts resulting from the presence of these substances under different environmental conditions. The methodology of this research consisted of computational modeling using the Hydrus 1D software, which allowed the simulation of solute transport and water flow in the soil over a period of 16 years (5,844 days). The case study focused on soils used in a sanitary landfill located in the semi-arid region of Paraíba, Brazil, which receives large volumes of urban and industrial waste, making it a strategic site for assessing the environmental impacts associated with soil pollution. The modeling was carried out using the geotechnical characterization of sandy soil and bentonite mixtures in proportions of 15%, 20%, and 25% (by mass), which are commonly used as liners in sanitary landfills. The results showed that the bentonite content significantly influences the contaminant containment over time. The 15% mixture showed higher cumulative water flow (20.75 cm/year) and lower copper retention, with a higher migration rate (262.67 mg/cm³/year), indicating greater vulnerability. In contrast, the 20% and 25% bentonite mixtures performed better, with higher adsorption rates and lower concentration gradients (0.01143 mg/cm³ and 0.00282 mg/cm³, respectively). The long-term simulation highlighted the importance of careful material selection for landfill liners, especially in vulnerable regions such as the semi-arid zone. It is concluded that mixtures with higher bentonite content are more effective in retaining copper, reducing leaching potential, and protecting the lower soil layers and aquifers.