Immobilization of New Isolated Iron Oxidizing Bacteria on Natural Carriers

Abstract

The bioleaching of sulfide minerals by iron oxidizing bacteria are implemented by direct and indirect mechanisms. The direct dissolution of minerals is caused by the attack of sulfide ions by enzymatic system of bacteria. In the indirect mechanism the ferric ion from oxidation of ferrous iron serves as a leaching agent that reacts chemically with the minerals. The increase of ferrous ion oxidation contributes to the intensification of bioleaching process. On this purpose the immobilization of iron oxidizing bacteria on different organic and inorganic carriers (calcium alginate, carragiran, ceramic support, activated carbon, porous glass, etc.) has been implemented which allows to increase cell concentration. In the present work for the first time the native shungit, zeolit and their chemically modified forms have been used for immobilization of new isolated iron oxidizing bacteria of the genera Leptospirillum and Sulfobacillus. Efficient physico-chemical conditions for immobilization on the mentioned carriers have been developed. The ferrous ion oxidation by immobilized cells has been studied both in shake-flasks experiments and in the glass column using air-lift process. It has been shown that in both cases the rate of iron oxidation considerably enhances in comparison with free cells.