Tiny microorganisms could play an important role in the future remediation of former uranium mines. For many years, environmental engineers have been investigating how natural processes can be harnessed to permanently bind uranium in mine water and thus prevent the spread of this contaminant.
It is well known that microorganisms are found in nearly all environmental settings. They adapt their metabolism to their surroundings and can thereby alter chemical substances. Environmental scientists are capitalizing on this effect: By selectively adding certain nutrients, they can influence the activity of the microorganisms. The goal is to convert dissolved uranium into a sparingly soluble form so that it remains in the rock and is no longer transported by the water.
Wismut GmbH, based in Chemnitz/Germany, has been investigating this method for about 20 years. The research focuses on two key questions: Can the formation of stable uranium minerals be specifically promoted? And do these minerals remain stable over the long term once the treatment is complete?
The method developed is already being applied in practice at the Königstein site. There, an injection system is used to introduce suitable substances into the flooded mine to stimulate the desired microbial processes. At the same time, researchers are investigating how durable the formed uranium minerals are. Previous experiments at other sites worldwide have shown that bound uranium can later dissolve again under certain conditions.
New findings are now provided by a joint study conducted by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and Wismut, which was published in the renowned journal *Nature Communications*. In the laboratory, the researchers analyzed mine water from Schlema. By adding glycerol—a readily available carbon source for microorganisms—they were able to bind approximately 95 percent of the previously dissolved uranium into solid minerals.
It is particularly noteworthy that these uranium compounds remained largely stable even after a four-week treatment under oxygen-rich conditions. Using state-of-the-art X-ray analysis, the researchers were able to demonstrate that, in addition to the expected uranium minerals, previously unknown uranium compounds had also formed. These could play a decisive role in making the bound uranium more resistant to being released again.
Why these compounds are so stable has not yet been fully elucidated. Further investigations will now determine whether the results can be confirmed.
For Wismut, this research is part of a long-term commitment. The remediation of former uranium mining sites is not a completed task but an ongoing process that continually requires new scientific insights. That is why Wismut is working together with research institutions to gain an ever-better understanding of natural underground processes and to further develop innovative remediation methods. Through its research, Wismut aims to accelerate the natural purification processes occurring underground. The goal is to reduce, as much as possible for future generations, the long-term environmental impacts of former uranium mining sites that have persisted for many decades.
Further information:
Wismut GmbH
www.wismut.de
