Comparative Assessment of Contaminant Sorption in Lateritic Soil—Bentonite Mixtures

The sorption of contaminants to lateritic soil treated with up to 10% bentonite by dry weight of soil through batch equilibrium tests using three municipal waste leachate solutions was considered. Test results were used to determine the partition (K_p)/distribution (K_d) coefficients of target contaminants namely, lead (Pb), sodium (Na) and potassium (K). For the natural soil, K_p/K_d values were established as 2.01 (Pb), 0.2 (Na) and 0.77 (K), while for samples containing 10% bentonite they were 3.97 (Pb), 0.46 (Na) and 3.03 (K). The removal capacity of the mixture containing 10% bentonite is about four fold that of the natural soil in the case of K⁺, twice for Na⁺and twice for Pb²⁺. Contaminant sorption increased with higher bentonite content and pH. Lateritic soil can be effectively utilized in the design of landfill liner systems by treating it with low percent bentonite.