Recycling of Rare Earth Elements

From Wastewater

🌱 Can bacteria recycle REEs from wastewater?

Researchers at the Technical University of Munich, in cooperation with the Kaiserslautern University of Applied Sciences, recycled REEs from an aqueous solution using previously unstudied bacterial strains. They “discovered that the biomass of some […] cyanobacteria can efficiently absorb REEs from wastewater”.

🌱 What are cyanobacteria and biosorption?

Cyanobacteria are also known as blue-green algae. Researchers recently discovered “that biomass derived from cyanobacteria has excellent adsorption characteristics due to its high concentration of negatively charged sugar components”. Therefore, the biomass “can adsorb amounts of REEs corresponding to up to 10% of its dry matter”. This happens through a metabolically passive process, called biosorption. The biosorption of REEs by cyanobacteria is fast, and possible even at low metal concentrations. As the process is reversible, the biomass can be reused. This makes it suitable for “future eco-friendly processes for simultaneous REEs recovery and treatment of industrial wastewater”.

🌱 What is the industrial potential?

The researchers plan to now test the large-scale application of the process. They expect biosorption to be “an economically and ecologically optimized process for the circular recovery and reuse of [REEs] from diluted industrial wastewater” in mining, metallurgy, and e-waste recycling.

From Fluorescent Lamps

🌱 Can viruses recycle REEs from fluorescent lamps?

Researchers at the Helmholtz Institute Freiberg for Resource Technology developed a process to recover REEs from fluorescent lamps using viruses, called bacteriophages.

🌱 What are bacteriophages and the PSD method?

Bacteriophages are viruses that primarily infect bacteria. Using the "Phage Surface Display" (PSD) technology an element-specific biomolecule can be selected from bacteriophages. The biomolecule can then be produced biotechnologically and anchored onto a spherical, magnetic carrier material. This creates biocollectors, which can specifically recognize and bind to a target element. By combining the PSD method with a special magnetic separation process, the researchers filtered REEs out from mixtures and were able to reuse the biocollectors.

🌱 What is the industrial potential?

The researchers expect to soon “bring [REEs] recovered by biocollectors back into circulation”, and thereby also reduce hazardous waste. Using lamp powder, they demonstrated that it is possible and economically viable to recover the elements it contains. As compact fluorescent lamps contain mercury, they are collected and stored separately in the EU. By 2020, the EU was estimated to have accumulated 25000 tons of fluorescent powder, containing 750 tons of REEs.