Rapid removal of uranium (VI) by phosphogypsum immobilized sulfate-reducing bacteria microspheres

The rapid development of the nuclear industry has caused uranium pollution, which is a significant environmental hazard. Microorganisms can be used to reduce the toxicity of hexavalent uranium (U(VI)) by converting it to tetravalent uranium (U(IV)). This is considered to be an effective method for repairing uranium pollution. In this study, to achieve rapid and stable uranium removal, we investigated the use of sulfate-reducing bacteria immobilized by phosphogypsum. Immobilized microspheres were assembled by combining the carrier with sulfate-reducing bacteria. The characterization revealed the ability to load bacterial cells on the carrier in large quantities, indicating good biocompatibility with sulfate-reducing bacteria. Compared to single phosphogypsum, the immobilized microsphere exhibited a rapid and stable ability to transform and remove uranium. At the same time, the reduction efficiency of U(VI) is affected by pH, adsorbent dosage, and initial metal ion concentration. The residual concentration of U(VI) was continuously detected, and it was found that the removal rate of uranium by phosphogypsum immobilized sulfate-reducing bacteria microspheres could reach 99.69 %, and the residual uranium concentration was 0.023 mg/L. Meanwhile, we found that P-O and Fe play an important role in the biomineralization of uranium.