Immobilization of Cd in the soil of mining areas by FeMn oxidizing bacteria

• Published in: The Science of the total environment Vol. 873; p. 162306
• Main Authors: Huang, Chiyue, Guo, Zhaohui, Peng, Chi, Anaman, Richmond, Zhang, Pan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.05.2023
• Subjects: Bacteria; Cadmium - analysis; Fe[sbnd]Mn oxidizing bacteria; Heavy metals; Immobilization; Metals, Heavy - analysis; Mining area; Soil - chemistry; Soil Pollutants - analysis; Soil pollution; Soil remediation; Mining area; Immobilization; Soil remediation; FeMn oxidizing bacteria; Soil pollution; Heavy metals
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.162306

Microorganisms are widely used in large-scale pollution remediation due to their rapid reproduction and low cost. In this study, bioremediation batch experiments and characterization methods were adopted to investigate the mechanism of FeMn oxidizing bacteria on the immobilization of Cd in mining soil. The results showed that the FeMn oxidizing bacteria successfully reduced 36.84 % of the extractable Cd in the soil. The exchangeable forms, carbonate-bound forms, and organic-bound forms of Cd in the soil decreased by 11.4 %, 8 %, and 7.4 %, respectively, due to the addition of FeMn oxidizing bacteria, while FeMn oxides-bound and residual forms of Cd increased by 19.3 % and 7.5 %, as compared to the control treatments. The bacteria promotes the formation of amorphous FeMn precipitates such as lepidocrocite and goethite, which have high adsorption capacity on soil Cd. The oxidation rates of Fe and Mn in the soil treated with the oxidizing bacteria reached 70.32 % and 63.15 %, respectively. Meanwhile, the FeMn oxidizing bacteria increased soil pH and decreased soil organic matter content, further decreasing the extractable Cd in the soil. The FeMn oxidizing bacteria have the potential to be used in large mining areas to assist in the immobilization of heavy metals. [Display omitted] •FeMn oxidizing bacteria reduced 36.84 % of the extractable Cd in the mining soil.•The bacteria promoted the formation of lepidocrocite and goethite in the soil.•The Fe and Mn oxidation processes increased soil pH and further reduced extractable Cd.•The bacteria reduced organic-bound forms of Cd in the soil by consuming SOM.•The effects of microorganisms and microbial carriers on Cd immobilization were compared.