Long-term stability and toxicity effects of three-dimensional electrokinetic remediation on chromium-contaminated soils

Zheng Wang; Xiao He; Xin Li; Liuzhou Chen; Tian Tang; Guodong Cui; Qiming Zhang; Yangsheng Liu

doi:10.1016/j.envpol.2023.122461

Long-term stability and toxicity effects of three-dimensional electrokinetic remediation on chromium-contaminated soils

Environ Pollut. 2023 Nov 15:337:122461. doi: 10.1016/j.envpol.2023.122461. Epub 2023 Sep 7.

Authors

Zheng Wang¹, Xiao He², Xin Li³, Liuzhou Chen⁴, Tian Tang⁴, Guodong Cui⁴, Qiming Zhang⁴, Yangsheng Liu⁵

Affiliations

¹ College of Environmental Sciences and Engineering, Peking University; Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing 100871, China. Electronic address: 2001111909@stu.pku.edu.cn.
² China MCC5 Group Corp. Ltd., Chengdu, 610063, China.
³ Ecological Environment Consulting Department, Beijing Construction Engineering Environmental Remediation Co., Ltd., Beijing 100015, China.
⁴ College of Environmental Sciences and Engineering, Peking University; Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing 100871, China.
⁵ College of Environmental Sciences and Engineering, Peking University; Beijing Key Laboratory for Solid Waste Utilization and Management, Beijing 100871, China. Electronic address: yshliu@pku.edu.cn.

PMID: 37689131
DOI: 10.1016/j.envpol.2023.122461

Abstract

The three-dimensional electrokinetic remediation (3D EKR) achieved efficient removal of chromium (Cr) from the soil through mechanisms including electromigration, electroosmosis, and redox reactions. In this study, the long-term stability, leaching toxicity, bioavailability, and phytotoxicity of Cr in remediated soils were systematically analyzed to comprehensively evaluate the effectiveness of the 3D EKR method. The results showed that the concentration of hexavalent chromium (Cr (VI)) in the leachate of the 3D EKR system with sulfidated nano-scale zerovalent iron (S-nZVI) was more than 40% lower than those of the other 3D electrode groups, and the time required to reach the level III standard of groundwater quality criterion in China (0.05 mg/L, GB/T 14848-2017) was significantly shortened. The stabilization of Cr(VI) in contaminated soil after 3D EKR was maintained for 300 pore volumes (PVs), indicating that the treated Cr(VI) had good long-term stability. The leaching toxicity and bioaccessibility of Cr were assessed by the synthetic precipitation leaching procedure (SPLP), the toxicity characteristic leaching procedure (TCLP), and the physiologically based extraction test (PBET). The concentration of Cr(VI) in the SPLP, TCLP, and PBET leachates of the S-nZVI group decreased by more than 25% compared to the other 3D electrode groups, corresponding to the decrease in leaching toxicity and bioavailability of the treated Cr during the 15-day remediation period. In addition, the germination rate of wheat seeds and the average biomass of wheat seedlings in the S-nZVI group under alkaline conditions (EE) were higher than those in the non-polluting group (Blank-OH), indicating that the remediated soil had no obvious toxicity to wheat. In summary, 3D EKR achieved a satisfactory and stable remediation effect on Cr-contaminated soil, especially when using S-nZVI as the 3D electrode.

Keywords: Cr-contaminated soil; Long-term stability; Sulfidated nano-scale zerovalent iron; Three-dimensional electrokinetic remediation; Toxicity.

MeSH terms

Chromium / analysis
Chromium / toxicity
Environmental Restoration and Remediation*
Iron
Soil
Soil Pollutants* / analysis
Soil Pollutants* / toxicity

Substances

chromium hexavalent ion
Soil Pollutants
Iron
Chromium
Soil