Efficient removal of uranium from contaminated groundwater post neutral in-situ leaching through microbial induced carbonate precipitation

The remediation of groundwater after in-situ leaching (ISL) for uranium mining has raised concerns worldwide. In this study, we evaluated the effectiveness of microbial induced carbonate precipitation (MICP) technique to treat uranium- contaminated groundwater containing carbonate for the first time. The effects of some key parameters on uranium (U) removal efficiency were explored. Moreover, the removal mechanism of U was investigated in-depth. The results show that the removal efficiency of U was significantly affected by initial pH and Ca 2+ concentration. Near neutral pH and Ca 2+ concentration of 0.15 mol/L is the most preferential for U removal. XRD data demonstrated that calcite was the main mineral formed in the process of MICP. Uranium is removed mainly due to co-precipitation with calcite. U removal efficiency of the real contaminated groundwater through MICP was 99% after mineralization for 5 d, indicating that MICP technique has great potential for the treatment of groundwater post neutral in-situ leaching.