Scientists from San Diego State University are researching the utilization of bacteria to filter Rare Earth Elements (REE) out of tailings and other mining residues.
To reduce the dependency on China and possibly limit the impact on the environment, researchers recently shifted their focus to the waste of domestic mining projects. Industrial residues contain varying amounts of Rare Earth Elements (REE), but they are difficult to extract. With funding from the Defense Advanced Research Projects Agency (DARPA), researchers from San Diego State University (SDSU) are now developing new extraction methods to increase the domestic supply of REEs.
According to biologist and principal investigator Marina Kalyuzhnaya, the researchers are “trying to develop a new procedure for recovery which is environmentally friendly and more sustainable.” To do this, the team attempts to utilize the natural propensity of methane-consuming bacteria to extract REEs from mine tailings and other mineral-containing waste material: The bacteria require REEs to regulate one of the central enzymatic reactions in their metabolic pathways, according to Kalyuzhnaya, and extract them from their surroundings. The SDSU researchers hence plan to reverse engineer the biological processes that allow the bacteria to harvest the metals from the environment. The team will then modify the bacteria to store the metal-binding proteins on the surface of their cells. In the future, the bacteria could be implemented into biofilters to purify mine tailings and collect the contained REEs.
Possible Application of Bacteria in Former Mining Regions
The researchers anticipate lower energy consumption and environmental benefits because the proposed system will function as a passive biofiltration system with theoretically fewer required solvents and solutions than currently used. The self-proposed target of the project is to provide proof-of-concept of the bacteria REE-recovery technology in four years. If successful, the project could help limiting the current dependency on China in the supply of REEs and REE-containing technology. Additionally, the results could be applied to former mining regions that are struggling with declining fossil fuel production. The Department of Energy announced last week that it will allocate $450 million to clean energy projects in existing and former mining regions.
The SDSU project is however not the first venture in harnessing bacteria for the extraction of REEs: Researchers from Technical University of Munich, in cooperation with Kaiserslautern University of Applied Sciences, are tapping into similar biofiltration properties of bacteria: The German-based researchers successfully tested the suitability of cyanobacteria for biosorption.