Linked variations of bioleaching performance, extracellular polymeric substances (EPS) and passivation layer in the uranium bacterial-leaching system

The linked variations of the bioleaching performance, extracellular polymeric substances (EPS) secretion, and passivation layer formation in the uranium bioleaching processes with chemoautotrophic acidophiles like Acidithiobacillus ferrooxidans (A. ferrooxidans), Acidithiobacillus thiooxidans (A. thiooxidans) and their mixed strains were explored. The results showed the uranium extraction of the mixed bacteria was better than that of the pure bacteria, and the uranium leaching rate achieved 97.5% at the optimized conditions. It showed that EPS production was lower at the favorable conditions, while increased in adverse surroundings, indicating EPS could contribute to the bacteria resistance. Furthermore, SEM/EDS analysis showed the jarosite production increased with the increase of pH/temperature. The mixed A. ferrooxidans and A. thiooxidans could inhibit the formation of passivation layer for presenting as symbiotic consortia.