Sustainable Use of Precious and Rare Metals Through Biotechnological Recycling

We proposed using new biotechnologies to recycle platinum group metals (PGMs) and gold from the end of life wastes, which will lead to the sustainable use of precious and rare metals. When targeting leachate of spent automotive catalysts, the metal ion-reducing bacterium Shewanella algae was found to reduce and deposit aqueous PGMs ions (Pd(II), Pt(IV) and Rh(III)) as metallic particles within the bacterial cells at room temperature and pH 6 within 60 min, using formate as the electron donor. We also found that the baker’s yeast Saccharomyces cerevisiae can be applied as a biomaterial for adsorbing Au(III) ions from aqueous acidic solutions. When processing leachate of spent electronic components, S. cerevisiae cells were able to rapidly and selectively collect Au(III) ions from strongly acidic solutions. Unlike conventional hydrometallurgical methods, our proposed microbial methods enable the attractive and eco-friendly recovery of PGMs and gold from secondary sources.