Bio-dissolution of hazardous Cu, As, Sb and Zn from polymetallic tetrahedrite by a moderately thermophilic consortium

The role of acidophilic microorganisms in tetrahedrite dissolution and their contribution to acid mine drainage (AMD) formation remains poorly understood. Herein, the dissolution of tetrahedrite mediated by a moderately thermophilic consortium (MTC) enriched and acclimated from acidic mine sediments was investigated. MTC significantly accelerated the dissolution of tetrahedrite. After 60 days of bio-dissolution, the concentrations of Cu²⁺, Zn²⁺, As^T and Sb^T in leachate reached 2.26 g/L, 16.48 mg/L, 348.07 mg/L, and 22.88 mg/L respectively. MTC mobilized 52.15% copper from tetrahedrite, which was 6-fold higher than abiotic control (7.41%). The dissolution of tetrahedrite occurs through oxidative attack by Fe³⁺, which decomposes the mineral, while MTC reoxidizes the generated Fe²⁺ to Fe³⁺ and oxidizes sulfur species to sulfate, thereby enabling sustained oxidative dissolution. SEM-EDS revealed that MTC significantly enhanced mineral oxidation, causing microbial attachment and corrosion pits. However, XRD and XPS indicated that prolonged leaching induced a passivation layer dominated by jarosite, S⁰/S^2- and Sb₂O₅. The MTC drives Fe³⁺ to oxidize As(Ⅲ)-O to As(V)-O. High-throughput sequencing analysis showed that Acidithiobacillus caldus, uncultured_archaeon_g__Aplasma, and Sulfobacillus thermotolerans were the dominant species through the bio-dissolution process. PICRUSt2 analysis showed enrichment of genes encoding copper efflux pumps (cusCBA), arsenic/antimony transport ATPases, and detoxification pathways, while arsenate reductase was downregulated to minimize toxic As³⁺ generation. This study provides novel insights into the bio-dissolution process of tetrahedrite mediated by acidophilic microorganisms, as well as highlights the potential of tetrahedrite in the generation of AMD.