Abstract: In this study, the factors of initial pH value, temperature, the added amount of bacterial liquid and the solid-liquid ratio on the remediation effect were explored by an experiment on the microbial remediation of uranium tailings, the uranium occurrence morphology and microbial community structure changes in the tailings before and after remediation were compared. The result shows that the SRB (sulfate-reducing bacteria) screened from the uranium tailings can reduce uranium concentration at seepage effectively; The effect of uranium tailings remediation was positively correlated with initial pH value, temperature, and added amount of liquid, but not significantly correlated with solid-liquid ratio; Under the adverse conditions of pH=3 or temperature at 15 ℃, the uranium concentration was reduced to 0.04 mg/L and 0.019 mg/L, the remediation efficiency could reach 96.9% and 93.6%, indicating good remediation efficiency. The residual uranium content increased by 14.6%-18.7%, the abundance of functional bacteria increased by 2.9%-12.2%, the mass proportion of insoluble uranium and the number and activity of reduction microorganisms increased significantly. The result shows that the remediation was stable. The result further verified that the microbial remediation technology of uranium tailings contamination is feasible.

Key words: uranium tailings, microbial remediation, biological reduction, sulfate-reducing bacteria, factors