THE STUDY OF THE ROLE OF BIOLOGICAL IRON SULFIDE COMPOSITES ON COPPER REMOVAL BY CHANGING GEOCHEMICAL FORMS

The growth of biological iron sulfide composites and their efficacy for changing the geochemical forms of copper in sediment have been investigated. The role of bacteria in copper removal was identified using copper concentrations in three forms extracted via three sequential extraction methods. Furthermore, bacterial community diversity was investigated between different treatments. Copper was transformed from the weak acidic extraction state to the reduction state and the oxidation state under the action of biological iron sulfide composites. The conversion rates of copper from the weak acidic extraction state to other states was up to 76.66% and the increasing rates of the reduction state was up to 177.85%. Higher dissolved oxygen does harm sulfate reducing bacteria and results in low removal efficiency of copper. It can be inferred that differences in the bacterial community structure resulted in differences between conversion rates and biological efficacy through the correlation between copper concentration and alpha diversity or beta diversity. Furthermore, bacterial 16S rRNA gene analysis showed that Proteobacteria, which sulfate reducing bacteria belong to, were predominant in the group with higher removal efficiency. The biological iron sulfide composites affected the removal efficiency of copper by increasing the sulfate reducing bacteria activity inside the sediments