Experimental Methodology to Assess Retention of Heavy Metals Using Soils from Municipal Waste Landfills

Municipal landfill soils are not able to retain heavy metals indefinitely, and these metals can migrate into the groundwater. Environmental contamination induced by toxic metals creates a societal health risk. The objective of this work is to study the ability of landfill soil to retain metals (Pb, Cd, Cu, Fe and Zn). The soil came from the municipal solid waste dump of the City of Yamoussoukro (Côte d’Ivoire). Operating parameters such as thickness of soil, metal concentration and filtered volume were investigated. A factorial experimental design was used to determine which parameters influence the metal retention rate. Thickness of soil and metal concentration were the most important factors influencing metal retention. Using a 2³ factorial matrix, the best performances for metal retention (99.8–100 % removal) were obtained by selecting a thickness of soil of 2.0 cm, an initial metal concentration of 50 mg L⁻¹ and 200 mL of metallic solution. The optimal experimental conditions for metal retention were then investigated using the Excel Solver program. Between 98.9 and 99.9 % of the metals were retained in subsequent experiments using these optimal conditions (soil thickness ranging between 10 and 14 cm and metal concentration of up to 300 mg L⁻¹ in 400 mL of metallic solution).