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

Xiaoming Zhao,Binbin Yang,Dongdong Li,Ke Xu,Yuan Li,Dongqi Tang,Bingxiang Yuan

doi:10.1155/2021/6630982

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.

Highlights

Mine tailings and wastewaters are created during the mining activity, which is one of the main sources of the heavy metal contaminants migration to the environment
Other studies indicated that the high concentration of lead (Pb), zinc (Zn), cadmium (Cd), and other heavy metals are found in the soil around the mining areas in the Xiangjiang Valley [3, 4]
Wang et al [1] investigated the heavy metal pollution in soil as well as vegetables in the Hunan Province and indicated that soil pollution posed a potential risk to human health and food safety. e traditional solution to heavy metal-contaminated soil is mixing cement-based binders such as Portland cement (PC) into the soil

Summary

Introduction

Mine tailings and wastewaters are created during the mining activity, which is one of the main sources of the heavy metal contaminants migration to the environment. E traditional solution to heavy metal-contaminated soil is mixing cement-based binders such as Portland cement (PC) into the soil. The application of PC and other cement-based materials would increase soil pH to a certain value that makes the stabilized soil unacceptable by plants and microorganisms [5]. Due to those shortcomings of the cement-based materials, it is very urgent to find a new alternative binder which is more eco-friendly. Contaminated soil used in this study, which was obtained from a mining field in Zhuzhou, Hunan, had a very high concentration of lead (12510 mg/kg) and zinc (11927 mg/kg), while limited research has been conducted on the effectiveness of biochar when applied into contaminated soil with that high concentration pollution. Two types of binders were used in this study, i.e., biochar and PC. e biochar was self-prepared from rice straws as a new type of a binder; PC was used for comparison purposes. 5%, 8%, and 10% content of the binder were added to contaminated soil

Materials and Methods

Results and Analyses

Untreated