Remediation of Cr(VI)-contaminated soil mixed with chromite ore processing residue by ferrous sulfate and enzyme residue

Kaiyu Shi; Yuxiu Zhang; Guoyu Ding; Xingrun Wang; Xianghua Yan; Hong Pan; Yuan Zhao

doi:10.1016/j.scitotenv.2023.164743

Remediation of Cr(VI)-contaminated soil mixed with chromite ore processing residue by ferrous sulfate and enzyme residue

Sci Total Environ. 2023 Sep 20:892:164743. doi: 10.1016/j.scitotenv.2023.164743. Epub 2023 Jun 10.

Authors

Kaiyu Shi¹, Yuxiu Zhang², Guoyu Ding³, Xingrun Wang⁴, Xianghua Yan⁴, Hong Pan⁴, Yuan Zhao⁵

Affiliations

¹ School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China; State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
² School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China. Electronic address: zhangyuxiu@cumtb.edu.cn.
³ Beijing Key Laboratory of Aqueous Typical Pollutants Control and Water Quality Safeguard, School of Environment, Beijing Jiaotong University, Beijing 100044, China. Electronic address: gyding@bjtu.edu.cn.
⁴ State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
⁵ School of Chemical and Environmental Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China.

PMID: 37302601
DOI: 10.1016/j.scitotenv.2023.164743

Abstract

In this study, Cr(VI)-contaminated soil mixed with COPR by using ferrous sulfate (FeSO₄), enzyme residue (ER), and their combination under aerobic or anaerobic condition were investigated. The concentration of Cr(VI) decreased from 1498.05 to 104.63 mg kg^-1 after the simultaneous addition of FeSO₄ (30 %, w/w as FeSO₄·7H₂O) and ER (30 %, w/w) at 45 d under the anaerobic condition with a reduction efficiency of 93.02 %, which is higher than that by single FeSO₄ (72.39 %) or ER (75.47 %) under the anaerobic condition. XRD, XPS, FTIR, and fluorescence spectroscopy were conducted to characterize soil and ER composition. Metagenomic analysis was performed to reveal the reduction mechanisms of FeSO₄ and ER. The anaerobic condition with lower Eh was beneficial for Cr(VI) reduction than aerobic condition, and Eh was the main driver for the evolution of Cr(VI) reduction-related microorganisms. Moreover, the addition of ER enriched the organic matter and microbials in the soil. During the decomposition of organic matter under the anaerobic condition, organic acids were generated, leading to a decrease in pH and promoting the release of Cr(VI) from minerals. They also served as electron donors in Cr(VI) reduction. Additionally, the addition of excess FeSO₄ stimulated the growth of iron-reducing bacteria and sulfate-reducing bacteria, facilitating to Cr(VI) reduction. Metagenomic analysis showed that Acinetobacter, related to the nemA and nfsA genes, was the dominant Cr(VI) reduction genus. Thus, the combination of FeSO₄ and ER is a promising method for the remediation of Cr(VI)-contaminated soils mixed with COPR.

Keywords: Chromite ore processing residue; Cr(VI); Reduction microbial community and genes; Remediation; Soil.

MeSH terms

Chromium / analysis
Ferrous Compounds* / chemistry
Industrial Waste / analysis
Soil
Soil Pollutants* / analysis

Substances

ferrous sulfate
chromium hexavalent ion
Ferrous Compounds
Chromium
Industrial Waste
Soil
Soil Pollutants