EFFECT OF FERROZINE AND AQS ON BIOREDUCTION OF HEMATITE IN THE PRESENCE OF SHEWANELLA SP.

Iron bioreduction in ferric minerals is an important process in behavior and bioremediation of contaminants. Organic matters are effective factors in bioreduction of ferric iron by iron reduction bacteria. They enhance iron reduction in hematite by two mechanisms: complexation and electron shuttling. An experiment was conducted under laboratory conditions in the form of a completely randomized design with 12 treatments and 3 replications to examine the function of AQS (as an electron shuttling) and ferrozine (as a complexing agent). The treatments included two controls (with and without Shewanella sp) and 5 levels of ferrozine (0.5, 1, 1.5, 2 and 2.5 mM), and 5 levels of AQS (10, 20, 30, 40 and 50 mM) in the presence of Shewanella sp in anaerobic chamber. The greatest amount of biological reduction of ferric iron was occurred in 2 mM ferrozine and 50 mM of AQS treatments. Ferrozine after 5 days and AQS after 1 day showed the greatest impact on bioreduction of ferric iron in hematite. So both complexation and electron shuttling had additive effect on the bioreduction of hematite.