Screening and selection of technologically applicable microorganisms for recovery of rare earth elements from fluorescent powder

Rare Earth Elements (REE) are essential elements in many new technology products. Nevertheless, recycling is poorly established and no environmentally friendly strategies are applied. Modern biotechnologies like bioleaching can contribute to overcome the current limitations. In this study, we tested different microorganisms to mobilize REE from used fluorescent phosphor (FP), as an exemplary REE containing waste product. Beneath, classical acidophilic microorganisms, various heterotrophic ones, producing organic acids or metal complexing metabolites, or having a high metal tolerance, were investigated. The three organic acids producing strains Komatogateibacter xylinus, Lactobacillus casei, and Yarrowia lipolytica leached larger amounts of REE. Besides the COOH-functionality, also other biotic processes contribute to metal leaching, as comparison with indirect leaching approaches showed. Preferably the red dye yttrium europium oxide (YOE) was leached from REE components of FP. The results provide the basis for the development of an environmentally friendly recycling process for REE from waste materials.