SMaRT: A sulfidogenic bioprocess for selective recovery of high-purity rare earth element minerals from acid mine drainage.

Rare earth elements (REEs) are indispensable for high-tech industries, yet primary mining faces intensifying geopolitical and environmental constraints. Acid mine drainage (AMD) represents a vast, untapped secondary resource, with REE inventories in two prominent mining basins constituting 20 %-60 % of United States and European Union annual consumption. However, selective REE recovery is hindered by high concentration of transition metals that interfere with trace REE separation during conventional treatment. Here, we report SMaRT (Sulfidogenic Metal removal and rare earth elements Recovery Technology), a novel bioprocess that achieves high-efficiency REE partitioning and AMD purification by harnessing biologically-mediated distinct ligand solubility behaviors. Unlike non-selective chemical neutralization, SMaRT generates a dynamic flux of biogenic sulfides and carbonates, enabling sequential transition metals precipitation as stable sulfide minerals while selectively sequestering REEs as high-purity carbonates. This framework capture approximately 70 % of REEs present in the raw AMD as a high-purity (∼97 %) mineral product, while removing over 99 % of Fe, Zn, and Cu. Techno-economic analysis demonstrates a net-positive economic return, with recovered product value significantly exceeding reagent costs. Thermodynamic modeling further underscores the robustness of SMaRT across diverse hydrochemical profiles, confirming its viability across varied global geochemical environments. By pairing economic viability with technical feasibility, SMaRT establishes a sustainable paradigm for global AMD remediation and critical mineral supply resilience, directly advancing United Nations Sustainable Development Goals for clean water and social equity.