In this work, uranium(VI) biomineralization by soluble ortho-phosphate from decomposition of the phosphate rock powder, a cheap and readily available material, was studied in detail. Penicillium funiculosum was effective in solubilizing P from the phosphate rock powder, and the highest concentration of the dissolved phosphate reached 220 mg L⁻¹ (pH = 6). A yellow precipitate was immediately formed when solutions with different concentrations of uranium were treated with PO₄ ³⁻-containing fermentation broth, and the precipitate was identified as chernikovite by Fourier transform infrared spectroscopy, scanning electron microscope, and X-ray powder diffraction. Our study showed that the concentrations of uranium in solutions can be decreased to the level lower than maximum contaminant limit for water (50 μg L⁻¹) by the Environmental Protection Agency of China when Penicillium funiculosum was incubated for 22 days in the broth containing 5 g L⁻¹ phosphate rock powder.

In order to investigate the influence of different concentrations of bicarbonate on the abundance of microbial communities capable of reducing U(VI) in groundwater, 7 groups of experiments incubated with lactate and amended with 7 initial concentrations of bicarbonate (0, 5, 10, 15, 20, 25, and 30 mM), respectively, were conducted. It was found that U(VI) concentration failed to decrease below the Chinese uranium wastewater discharge standard (0.05 mg L⁻¹) when the initial bicarbonate concentration was higher than 10 mM. During the nitrate reduction, the abundance of nitrate reduction bacteria (NRB) was 22% in B0, while the abundance of NRB was 3.4% in B10 and B15. The main functional microbial community in B0 was NRB Brevundimonas, whose abundance was over 19%. During the U(VI), sulfate, and Fe(III) reduction, the abundance of sulfate and Fe reduction bacteria (SRB and FRB) was 44% in B0, while the abundance of SRB and FRB were 26% and 27% in B10 and B15, respectively. The main functional microbial communities capable of reducing U(VI) in B0 were Cellulomonas, Desulfosporosinus, and Desulfovibrio, whose abundance was as high as 36%. The main microbial community capable of reducing U(VI) in B10 was Desulfitobacterium, and its abundance was higher than 14%. The main functional microbial communities capable of reducing U(VI) in B15 were Desulfovibrio and Geobacter, and their abundance was over 13%. The overall experimental results indicate that the higher initial bicarbonate concentration leads to the lower abundance of microbial communities capable of reducing U(VI) in groundwater.

The surface of Bacillus megaterium was modified by coating sodium alginate. The modified B. megaterium before and after adsorption were characterized by SEM, FTIR and XPS. The effects of pH, reaction time, initial U(VI) concentration and adsorbent dosage on the adsorption of U(VI) by the modified B. megaterium were studied by batch adsorption experiments. The adsorption process was studied by pseudo-first-order kinetics and pseudo-second-order kinetic models, Langmuir and Freundlich isotherms. The results showed that the maximum adsorption capacity of U(VI) was 74.61 mg g ⁻¹ under the conditions of pH 5.0, adsorbent 0.2 g l ⁻¹ , 30°C and initial U(VI) concentration of 15 mg l ⁻¹ . The adsorption process accords with pseudo-first-order kinetics and Langmuir isotherm. The adsorption capacity of U(VI) by the modified B. megaterium was still higher than 80% after five times of desorption and reuse experiments. In conclusion, the sodium alginate modified B. megaterium was an ideal material for U(VI) biosorption.