Effects of forced aeration on community dynamics of free and attached bacteria in copper sulphide ore bioleaching

Bacterial community dynamics and copper leaching with applied forced aeration were investigated during low-grade copper sulphide bioleaching to obtain better bioleaching efficiency. Results illustrated that appropriate aeration improved bacterial concentrations and leaching efficiencies. The highest bacterial concentration and Cu2+ concentration after 14-d leaching were 7.61 x 10(7) cells center dot mL(-1) and 704.9 mg center dot L-1, respectively, at aeration duration of 4 h center dot d(-1). The attached bacteria played a significant role during bioleaching from 1 to 7 d. However, free bacteria dominated the bioleaching processes from 8 to 14 d. This phenomenon was mainly caused by the formation of passivation layer through Fe3+ hydrolysis along with bioleaching, which inhibited the contact between the attached bacteria and ore. Meanwhile, 16S rDNA analysis verified the effect of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans on the bioleaching process. The results demonstrate the importance of free and attached bacteria in bioleaching.

Automated summary

This study investigated the dynamics of bacterial community and copper leaching during low-grade copper sulphide bioleaching with forced aeration. The results showed that appropriate aeration improved bacterial concentrations and leaching efficiencies. Attached bacteria played a significant role in the early stages of bioleaching, while free bacteria dominated the later stages due to the formation of a passivation layer.