Evaluation of the remediation effect of solid waste synergistic materials on heavy metal-contaminated soil

Abstract

In this study, we investigated the effect of various solid waste materials such as fly ash (CFA), steel slag, and kaolinite on the simultaneous stabilization of As, Cd, Cu, Pb, and Zn in the soil of abandoned lead-smelting slag plant. Synchronous stabilization of HMs in highly contaminated soils was achieved using the application of 29% formulated material Fe/Ca-Si based co-remediation material (FCS) with a ratio of FeSO4 + CFA + kaolinite of 14%: 12%: 3%, the bioavailable content of HMs As, Cd, Cu, Pb, and Zn was reduced by 71.55%, 49.62%, 91.35%, 61.37%, and 41.45%, respectively, and had little effect on the pH of the soil. Leaching toxicity analyses guaranteed the safety of restorative materials. The results of the field validation experiments showed that the FCS was able to effectively reduce the content of HMs in plant rhizomes and stabilized with maintenance time. European Community Bureau of Reference (BCR) and Wenzel sequential extraction procedures showed that FCS promoted the transformation of HMs in soil from unstable to stable phases. The analysis of soil microbial community diversity by FCS showed that it created a favorable soil living environment for microorganisms and was conducive to the stabilization of HMs. SEM, Surface scanning analysis, XRD, and FTIR results showed that FCS reacts with HMs to form a stable phase. Cost analysis showed that it has certain economic benefits. In conclusion, FCS is feasible for soil remediation in lead-smelting slag-polluted areas and also provides a way for high value-added utilization of solid waste.