Effect of simultaneous use of ferrozine and AQS in bioreduction of ferric iron in hematite

Iron reduction in ferric minerals has an impressive role in bioremediation of organic and nonorganic contaminants and understanding the efficient factors in this process will be important. Organic matters are effective in bioreduction of ferric iron with different mechanisms such as electron shuttling and complexation. In order to examine the effect of simultaneous use of AQS (as an electron shuttling) and ferrozine (as a complexing agent) in bioreduction of ferric iron in hematite an experiment was conducted under laboratory conditions in the form of a completely randomized design with 24 treatments and 3 replications in the presence of Shewanella spp. Control treatments included 6 variable concentration of ferrozine (0، 0. 5، 1، 1. 5، 2 and 2. 5 mM) and 6 variable concentration of AQS (0، 10، 20، 30. 40 and 50 μM) and compound treatments included variable concentrations of ferrozine with fix concentration of AQS (50μM) and variable concentrations of AQS and constant concentration of ferrozine (2mM). Produced soluble and acid extractable Fe (II) in compound treatments with variable ferrozine levels and constant concentration of AQS increased with increasing concentrations of ferrozine but in treatments with different levels of AQS and constant concentration of ferrozine didn’t show significant difference. Therefore، effects of both ferrozine and AQS were additive on bioreduction. However، none of these two compounds were solely dominant for increasing ferric iron bioreduction process in hematite.