Microbial biominers: Sequential bioleaching and biouptake of metals from electronic scraps

Abstract

Electronic scraps (e‐scraps) represent an attractive raw material to mine demandedmetals, as well as rare earth elements (REEs). A sequential microbial‐mediated pro-cess developed in two steps was examined to recover multiple elements. First, wemade use of an acidophilic bacteria consortium, mainly composed of Acidiphiliummultivorum and Leptospidillum ferriphilum, isolated from acid mine drainages. Theconsortium was inoculated in a dissolution of e‐scraps powder and cultured for15 days. Forty‐five elements were analyzed in the liquid phase over time, includingsilver, gold, and 15 REEs. The bioleaching efficiencies of the consortium were >99%for Cu, Co, Al, and Zn, 53% for Cd, and around 10% for Cr and Li on Day 7. Thesecond step consisted of a microalgae‐mediated uptake from e‐scraps leachate. Thestrains used were two acidophilic extremotolerant microalgae, Euglena sp. (EugVP)and Chlamydomonas sp. (ChlSG) strains, isolated from the same extreme environ-ment. Up to 7.3, 4.1, 1.3, and 0.7 µg by wet biomass (WB) of Zn, Al, Cu, and Mn,respectively, were uptaken by ChlSG biomass in 12 days, presenting higher effi-ciency than EugVP. Concerning REEs, ChlSG biouptake 14.9, 20.3, 13.7, 8.3 ng ofGd, Pr, Ce, La per WB. Meanwhile, EugVP captured 1.1, 1.5, 1.4, and 7.5, respec-tively. This paper shows the potential of a microbial sequential process to revalorizee‐scraps and recover metals and REEs, harnessing extremotolerant microorganisms