Investigation of effective factors in the biooxidation of iron by Acidithiobacillus ferrooxidans

Articles in Press

Document Type : Original Article- Persian

Authors

1 Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran

2 Nuclear Science and Technology Research Institute, Tehran, Iran

3 Nuclear Fuel Cycle Research School, Nuclear Science and Technology Research Institute, Tehran, Iran

Abstract

Along with the growth in industrial activity, particularly due to the exploitation of easily processable metal resources, there comes a concern about a gradual decrease in these metal deposits. Consequently, the development of environmentally friendly technologies capable of extracting metals from complex and refractory sources has gained significant importance. Biohydrometallurgy is recognized as a green and sustainable technology that relies on iron-oxidizing microorganisms to facilitate metal dissolution. These microorganisms contribute to the leaching process through the production of ferric iron, which act as an effective and low-cost oxidizing agent. In this study, the individual and interactive effects of the operational parameters, pulp density, time, and bacterial inoculum, on ferric iron production in the copper bioleaching from the Kal-e-Kafi ore using uranium-resistant Acidithiobacillus ferrooxidans strain THA3 were investigated. The experiments were designed using a central composite design within the framework of response surface methodology. The results indicated that increasing the time from 2 to 21 days led to a decrease in ferric concentration from 1695.86mg/L to 135.36mg/L. Similarly, an increase in pulp density from 5% to 15% resulted in a reduction of ferric production from 1590.86mg/L to 838.34mg/L. On the other hand, when the bacterial inoculum was increased from 5% to 14.7%, there were increases in ferric production from 520.89mg/L to 1269mg/L. The proposed statistical model demonstrated satisfactory predictive performance, with a P-value=0.0022 and R²=0.93. The key innovation of this work is the combination of efficient bacterial strains with a central composite design to model and simultaneously analyze the influences of the most important operational factors for ferric iron production. The statistically efficient method of this work has been effective in reducing trial and error to a considerable extent for optimizing operational factors to move forward with innovations in the aspect of native bacterial strains for bioleaching on a larger scale.

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Journal of Microbial Biology

Articles in Press, Accepted Manuscript
Available Online from 17 June 2026

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