Geoenvironmental behaviour of lead-contaminated clay with sawdust

Abstract

Clayey composite liners are appointed in modern landfills to isolate wastes from the environment and minimise the escape of contaminants that are affecting the groundwater and the subsoil. Enhanced compressibility and reduced permeability are considered favourable; however, the ameliorating liners are at risk of losing these properties and thus the ability to contain the contaminant due to changing pH and contaminant contents during the long course of service. This research investigated the change in the mechanical properties, namely, the compression index c c, permeability coefficient K and void ratio–effective stress curve e against log σ′ of bentonite clay treated with chemically modified sawdust contents and laced with various lead nitrate (Pb(NO3)2) concentrations. The optimum values were simultaneously achieved for c c and K, in the 10% sawdust of pH 10 design, with lead (Pb) concentration <150 cmol/kg soil, and in the 30% sawdust of pH 10 design, with lead concentration between 150 and 250 cmol/kg soil; therefore, these were the optimum designs with best returns in terms of the given geotechnical properties, for the given lead concentrations. In both acidic and alkaline states, K decreased in different lead concentrations, with the introduction of the 10–30% sawdust, which is the range of amount proposed in field applications.

Phytoremediation: green technology for improving aquatic and terrestrial environments

“…Lead is the most immobile heavy metal compare to Cd, Cu, Zn, Ni and Cr (Kumar et al, 1995). On the other hand, attendance of organic matters decrease the risk of contamination transport to the groundwater (Mohajeri et al, 2018) so, for enhancing translocation of lead in soil media and plant tissues, some amendments such as chelators beside acidifier could be a suitable method (Salt et al, 1995). In a research on Salvinia minima as hyperaccumulator of Pb and Cd (Sánchez-Galván et al, 2008), intracellular accumulation and bioadsorption are mentioned as contribute mechanisms for hyperaccumulation process.…”

Enhancing the Adsorption of Lead (II) by Bentonite Enriched with pH-Adjusted Meranti Sawdust

“…From the geo-environmental point of view, the heavy metals are adsorbed by lignin rather than cellulose and hemicellulose [26]. From the mechanical properties of composite materials, the physical strength of clay soil system including sawdust was obtained using the cellulose and hemicellulose [27]. The adsorption bands at 2939 cm -1 and 2880 cm -1 are due to a contribution from C-H stretching that can prove the presence of the vinyl and methyl groups.…”

“…The particle size directly effects on the surface area. This limitation was chosen based on the previous studies [27,31]. Intra-particle diffusion research shows that the adsorption rate is directly under the influence of particle size [32].…”