The remediation technology for U(VI), Ca²⁺ and other pollutants in the groundwater of the mining area of in-situ leaching of uranium has become a key technical bottleneck restricting the decommission of uranium mine, and the microbial-induced calcium carbonate precipitation (MICP) technology can well mineralize and remove heavy metals in the groundwater.

This study aims to remove the pollutants in groundwater of uranium mining areas with MICP.

First of all, bacillus pasteurianus was selected, and its acid resistance and tolerance to uranium were analyzed. Then, the effects of initial U(VI) concentration, initial Ca²⁺ concentration, initial pH value, concentration of bacterial solution, and the time of mineralization on the removal of pollutants by MICP were explored. In addition, scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were employed to characterize the composition and microstructure of the mineralization products of MICP, in order to reveal the mechanism of mineralization and decontamination. Finally, water with low uranium concentration was treated by bacillus pasteurianus to verify the application of MICP.

The results show that Bartonella pasteurii has good urease activity at pH value of 4 and can adapt to the groundwater containing U(VI) concentration of 100 mg?L^-1. When the initial pH value is 4, the initial uranium concentration is 50 mg?L^-1, the Ca²⁺ concentration is 8 000 mg?L^-1, and the time of mineralization by MICP is 48 h, the removal rates of U(VI) and Ca²⁺ in the groundwater are 61% and 54%, respectively. The removal rate of U(VI) further increases to 91% when the initial pH value is increased to 7. Meanwhile, the increase of Ca²⁺ concentration promotes the removal of U(VI) in groundwater by MICP, however, the removal rate of Ca²⁺ is relatively low if the concentration of Ca²⁺ is too high.

The composition of MICP mineralization products is mainly uranium-containing calcium carbonate, in which the uranium is immobilized mainly by co-precipitation. Therefore, Bacillus pasteurianus can well remove U(VI) and Ca²⁺ in the groundwater of the mining area of in-situ leaching of uranium, and has a good prospect of application.