Microbial Strategies for the Bioleaching of a Copper- and Zinc-Rich Multimetallic Powder Addressing Challenges in Copper Recovery

Abstract

Traditional hydrometallurgical metal recovery methods rely on strong acids or bases, posing environmental and economic challenges. Bioleaching has emerged as a promising alternative, harnessing microbial activity for metal dissolution under milder conditions. In this study, we investigated the bioleaching of a copper- and zinc-rich multimetallic powder using Acidithiobacillus thiooxidans, Acidithiobacillus ferrooxidans, their co-culture, and Priestia megaterium. The bioleaching process involved bacterial pre-incubation followed by the addition of the powder, with leaching yields monitored over 14 days. The co-culture exhibited efficiency comparable to those of single cultures (> 90%), with enhanced selectivity towards Cu and Zn. In contrast, P. megaterium showed a maximum leaching yield of 7% for copper and 4% for zinc. Control experiments using autoclaved culture broth confirmed the microbial contribution to metal dissolution. To compare bioleaching with conventional methods, we also tested the leaching of the same powder using HCl, HNO₃, H₂SO₄, H₃PO₄, NaOH, acetic acid, and citric acid, obtaining comparable results with respect to bioleaching in terms of leaching yield and selectivity. These results underscore the potential of microbial consortia in bioleaching and highlight the need for optimized strategies to enhance metal recovery in future resource management.

Keywords: Bioleaching, Copper recovery, Spent catalyst, Bacteria, Selective leaching, Sustainable hydrometallurgy