Avaliação do transporte difusivo de níquel em solos utilizados em camada de base de aterro sanitário no semiárido paraibano

Abstract

Soil and groundwater contamination resulted from heavy metal the migration in bottom layers of landfills requires investigations of the building materials used in these layers, which must have low hydraulic conductivities. Therefore, it is expected to find low flow losses, and the dominance of the diffusion mechanism is these layers. The objective of this thesis was to evaluate the diffusive transport of nickel in compacted soils used in the bottom layer of the Sanitary Landfill in Campina Grande-PB. Nickel was transported in a compacted layer of local soil (SM) and bentonite clay (CL) mixtures, by the physical process of chemical diffusion. These tests followed a factorial design, to verify the influence of the variables (nickel concentration and bentonite clay content in the mixture) in obtaining the diffusion coefficient. The Equivalent Contaminated Layer (CCE) solution was used with the time and space assessment of nickel behavior over the soil configurations used. The estimation of the adsorptive parameters of this contaminant was obtained through the batch balance test. The results demonstrated that nickel diffusive transport occurred in the soils studied in this research and the percentage of bentonite clay was the determining variable in the retention of this metal. The effective displacement coefficients determined using the CCE solution were obtained in the litarature review and ranged between 2.02 x 10^-11 to 3.62 x 10^-11 m².s^-1. Besides, the individual soils and general compositions behave in a favorable way to nickel adsorption, better adjusted by the criteria of R², MSE, and AIC to the Freundlich isotherm model.