Attenuation of contaminants in landfill leachate by lateritic soil enhanced with bentonite: Fid-Bau Portal

Attenuation of contaminants in landfill leachate by lateritic soil enhanced with bentonite

Amadi, Agapitus / Odedede, O.

The current research was carried out to evaluate improvement in the attenuative capacity of lateritic soil for landfill leachate contaminants as a result of bentonite addition. Laboratory batch adsorption test was performed using lateritic soil treated with 0%, 2.5%, 5%, 7.5% and 10% bentonite by dry weight of soil with Pb²⁺ and K⁺ ions as selected contaminants in the landfill leachate. The experimental data were analysed by both the linear and Freundlich isotherms. In this study, the untreated lateritic soil achieved about 85% and 81% removal efficiencies for K⁺ and Pb²⁺ species, respectively, while 90% and 97% removal efficiencies were achieved by lateritic soil mixed with 10% bentonite. Maximum Pb²⁺ adsorption capacities for soil mixtures with 0%, 2.5%, 5%, 7.5% and 10% bentonite were 1.48, 1.51, 1.55, 1.58 and 1.6 mg/g, respectively, leading to K_d values ranging from 30.04 to 77.72 mL/g, while the adsorption capacities calculated for K+ ranged from 797.68 to 907.82 mg/g with corresponding K_f values of 59.7–206.54. Correlation coefficients indicate that the adsorption data for Pb²⁺ were adequately described by the linear model while the adsorption equilibrium data for K⁺ ion fitted well to the Freundlich isotherm model. Overall, the soil mixture with higher bentonite contents produced enhanced adsorption capacities for both Pb²⁺ and K⁺ ions.