Effects and driving mechanisms of bioremediation on groundwater after the neutral in situ leaching of uranium

• Published in: The Science of the total environment Vol. 946; p. 174406
• Main Authors: Lian, Guoxi, An, Yifu, Sun, Juan, Yang, Bing, Shen, Zhenyao
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 10.10.2024
• Subjects: bioaugmentation; Biodegradation, Environmental; biomineralization; biosorption; biotransformation; carbonates; China; environment; groundwater; Groundwater - chemistry; groundwater contamination; Groundwater remediation; High-throughput sequencing; Microbe; Mining; Neutral in situ leaching (NISL) for uranium mining; Uranium; Uranium - metabolism; Water Pollutants, Radioactive - analysis; Water Pollutants, Radioactive - metabolism; China; Groundwater remediation; Neutral in situ leaching (NISL) for uranium mining; Microbe; Uranium; High-throughput sequencing
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2024.174406

The remediation of groundwater subject to in situ leaching (ISL) for uranium mining has raised extensive concerns in uranium mill and milling. This study conducted bioremediation through biostimulation and bioaugmentation to the groundwater in an area in northern China that was contaminated due to uranium mining using the CO2 + O2 neutral ISL (NISL) technology. It identified the dominant controlling factors and mechanisms driving bioremediation. Findings indicate that microorganisms can reduce the uranium concentration in groundwater subject to NISL uranium mining to its normal level. After 120 days of bioaugmentation, the uranium concentration in the contaminated groundwater fell to 0.36 mg/L, achieving a remediation efficiency of 91.26 %. Compared with biostimulation, bioaugmentation shortened the remediation timeframe by 30 to 60 days while maintaining roughly the same remediation efficiency. For groundwater remediation using indigenous microbial inoculants, initial uranium concentration and low temperatures (below 15 °C) emerge as the dominant factors influencing the bioremediation performance and duration. In settings with high carbonate concentrations, bioremediation involved the coupling of multiple processes including bioreduction, biotransformation, biomineralization, and biosorption, with bioreduction assuming a predominant role. Post-bioremediation, the relative abundances of reducing microbes Desulfosporosinus and Sulfurospirillum in groundwater increased significantly by 10.56 % and 6.91 %, respectively, offering a sustainable, stable biological foundation for further bioremediation of groundwater. [Display omitted] •Bioremediation applied to remediation of groundwater contaminated by NISL.•Bioaugmentation was more effective than biostimulation.•The initial uranium concentration and temperature emerge as dominant factors that influence the remediation performance.•Desulfosporosinus and Sulfurospirillum dominated the reducing communities.