Permeable reactive barrier of waste sludge from wine processing utilized to block a metallic mixture plume in a simulated aquifer

Abstract

Heavy metal contamination in underground water commonly occurs in industrial areas in Taiwan. Wine-processing waste sludge (WPWS) can adsorb and remove several toxic metals from aqueous solutions. In this study, WPWS particles were used to construct a permeable reactive barrier (PRB) for the remediation of a contaminant plume comprising HCrO4−, Cu2+, Zn2+, Ni2+, Cd2+, and AsO33− in a simulated aquifer. This PRB effectively prevented the dispersals of Cu2+, Zn2+, and HCrO4−, and their concentrations in the pore water behind the barrier declined below the control standard levels. However, the PRB failed to prevent the diffusion of Ni2+, Cd2+, and AsO33−, and their concentrations were occasionally higher than the control standard levels. However, 18% to 45% of As, 84% to 93% of Cd, and 16% to 77% of Ni were removed by the barrier. Ni ions showed less adsorption on the fine sand layer because of the layer's ineffectiveness in multiple competitive adsorptions. Therefore, the ions infiltrated the barrier at a high concentration, which increased the loading for the barrier blocking. The blocking efficiency was related to the degree of adsorption of heavy metals in the sand layer and the results of their competitive adsorption. HIGHLIGHTS A wine-processing waste sludge (WPWS) permeable reactive barrier (PRB) successfully prevented the spread of HCrO4−, Cu2+, and Zn2+.; WPWS PRB had an extremely high affinity to HCrO4−.; WPWS PRB had a low affinity to AsO33−.; Multiple competitive adsorption results showed WPWS PRB as a poor block to Ni2+.; Adsorption from sand layer to metals also affected the block efficiency.;

Keywords

• aquifer
• heavy metals
• permeable reactive barrier
• sludge