Application of Biochar in the Remediation of Contaminated Soil with High Concentration of Lead and Zinc

Abstract

Soil contamination in the Panjiachong lead and zinc mining areas has become a severe problem in Hunan Province, China. As the traditional stabilization technology comes with soil degradation, it is urgent to find a novel binder that is more eco-friendly. It has been proved that biochar can immobilize heavy metals, but limited research has been conducted on the contaminated soil with high concentration. In this study, 5%, 8%, and 10% biochar derived from the rice straw were used to remediate contaminated soil with high concentration of lead and zinc. Portland cement (PC) was adopted as the control group. The results showed that after 56 d curing, the biochar-treated soil had a neutral pH and EC value and higher soil fertility compared with the PC-treated soil. The results from the toxicity characteristic leaching procedure test indicated that the biochar is more effective than PC on heavy metal immobilization. Germination index (GI) value was used to evaluate the phytotoxicity of the treated soil; the GI values of treated soil with 8% and 10% biochar were both higher than 80%, while all the PC-treated groups failed to achieve this GI value, which indicated the potential revegetation is applicable for the biochar-treated soil.