CHALLENGES TO THE BIOTECHNOLOGICAL RECYCLING OF PRECIOUS AND RARE METALS SOURCED FROM POST-CONSUMER PRODUCTS

摘要

We have developed new recycling technologies, based upon an eco-friendly biotechnology, in order to extract precious and rare metals sourced from post-consumer products. Recently we have been focusing on the metal ion-reducing bacteria, Shewanella algae and Shewanella oneidensis, which are able to reduce and deposit the precious metal ions (gold (III), platinum (IV), palladium (II), and rhodium (III)) into metal nanoparticles at room temperature within 120 min. When targeting the leachates from printed circuit boards, the Shewanella bacteria were able to allow selective reduction and deposition of gold (III) ions under acidic conditions in the presence of heavy metal ions, proposing a new bio-recovery system for gold. We also found that the Shewanella bacteria can separate and concentrate soluble rare metal ions (dysprosium (III), indium (III), and gallium (III)) from dilute solutions. Using this biomass adsorbent, the effectiveness of system for the novel recovery of indium from the leachate of used LCD (liquid crystal display) panels has been demonstrated.