Bioremediation of Uranium-Contaminated Water Using Native Microbial Consortia

A commonly acknowledged environmental issue is the water pollution caused by uranium compounds in areas where uranium is mined and processed. It is known that the bacteria naturally found in radioactively contaminated sites are adapted to polluted environments, particularly in the presence of heavy metal ions and radionuclides. These bacteria can more completely oxidize carbon sources, generating a stronger reducing potential needed to convert hexavalent uranium into its insoluble tetravalent form. Consequently, microbiological methods can be employed in purification technologies for water to remove toxicants.

This investigation aimed to study the possibility of effectively using bioreducers based on a local consortium of microorganisms from the uranium mine regions of Ukraine to purify uranium-containing water.

Microorganisms were sourced from various soil depths (1-3 meters) near the uranium industry tailing in Zhovti Vody City, Ukraine. A consortium of native bacterial cultures was cultivated under anaerobic conditions (Postgate C medium, cysteine, yeast). The formation of a black deposit on the dish walls and the strong smell of hydrogen sulfide indicated the effectiveness of the uranium reduction process. X-ray fluorescence analysis showed a decrease in the uranium concentration in the liquid phase, with the efficiency of water purification from uranium reaching 93%. So, sulfate-reducing bacteria (Desulfovibrio desulfuricans and Desulfovibrio vulgaris) can reduce uranium by an enzymatic mechanism. The products of these reduction reactions could be U(IV)-oxide minerals such as uraninite. Thus, the results confirm the feasibility of applying the microbiological method to uranium-contaminated water purification.