# Development of Technology for the Boleaching of Uranium in a Solution of Bacterial Immobilization
###### Abstract  
This study presents findings regarding the kinetics of ferrous iron oxidation in solution mediated by _Acidithiobacillus ferrooxidans_ bacteria within a continuous-flow bioreactor employing diverse types of immobilizers. The objective is to augment the rate of ferrous iron oxidation in solutions utilizing an immobilizer for _Acidithiobacillus ferrooxidans_ strains. Immobilization represents a promising avenue for enhancing the efficiency of Fe\({}^{2+}\) oxidation via acidophilic ferrooxidizing bacteria, leading to a several-fold increase in oxidation rate. A comparative analysis was conducted to evaluate the efficacy of different types of immobilizer in facilitating iron oxidation within a continuous-flow bioreactor, including the application of wood chips coated with Fe(OH)\({}_{3}\). The results indicate that wood chips coated with iron hydroxide serve as effective type of immobilizer, facilitating the robust attachment of _Acidithiobacillus ferrooxidans_ via electrostatic interactions between negatively charged bacteria and positively charged surfaces. Experimental investigations were conducted using novel immobilization matrices in pilot-scale tests simulating the underground borehole leaching (UBL) of uranium. The bioactivation of leaching solutions enhances the efficiency and environmental compatibility of UBL compared to conventional chemical oxidation methods. The relationships between redox potential and ferric iron content in bioactivated solutions during the UBL of uranium were delineated. The significance of this study lies in its elucidating the pivotal role of Fe\({}^{2+}\) oxidation in uranium extraction processes, particularly in the context of UBL. By employing bioactivation mediated by _Acidithiobacillus ferrooxidans_, the study demonstrates not only enhanced uranium extraction efficiency, but also markedly improved environmental sustainability compared to traditional chemical oxidation methods. The findings reveal crucial correlations between redox potential and ferric iron concentration in bioactivated solutions. immobilized; oxidation rate; divalent iron; trivalent iron; bacteria; _Acidithiobacillus ferrooxidans_; flow bioreactor; wood chips +
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introduced into the ore body, oxidizes the poorly soluble tetravalent uranium to its soluble hexavalent form, which is then carried to the surface in a productive solution. The utilization of ferric iron as a biogenic oxidizer yields economically and environmentally efficient outcomes compared to chemically obtained ferric iron. Indigenous strains of A. Ferrooxydans, obtained from the ore deposit, readily adapt to the solution in the bioreactor, subsequently becoming activated and immobilized on the immobilizer. Kazakhstan's uranium mines annually expend significant sums on the procurement of chemical oxidizers (hydrogen peroxide, etc.). Utilizing iron biooxidation increases the uranium content in the productive solution by 40%. Investigating and determining the use of a bacterial immobilizer to enhance the bacterial concentration in the bioreactor is a pertinent task. The literature on the utilization of bacterial strains A. Ferrooxydans via an immobilizer in uranium production remains limited. Existing studies primarily focus on the use of polymetallic ones and gold deposits in the disruption of the crystalline lattice of refractory gold-bearing sulfide minerals. Chemical oxidation [1] involves the loss and acquisition of electrons by substances in aerobic and anaerobic conditions and is used in the creation of chemical compounds. Electrochemical oxidation, accompanied by electron transfer between substances through electrodes in an electrolyte, is employed for energy generation and compound synthesis. Biological oxidation [2] plays a significant role in the energy exchange of living organisms, facilitating the processing of nutrients. The biological oxidation of Fe\({}^{2+}\) plays a pivotal role in the technology used in the bioleaching of various metals from ores, including uranium.