Microbial community induced calcium carbonate precipitation: Growth characteristics, product traits, and thorium and...

Microbial-induced mineralization presents substantial prospects for heavy metal immobilization in environmental applications, where microbial consortia offer enhanced environmental adaptability and cost-effectiveness compared to single-strain approaches. This study employs carbonate-mineralizing microbial communities to induce CaCO₃ precipitation for the immobilization of Thorium (Th) and Uranium (U) in aqueous solutions. The microbial community A1, derived from rare earth waste residue, demonstrated strong urease activity and exhibited markedly enhanced growth and urease expression when cultivated with composite carbon‑nitrogen sources compared with single carbon sources. Under different culture conditions, the microbial community A1 consortium predominantly induced the formation of calcite-and vaterite-type calcium carbonate. The consortium achieved high removal efficiencies, eliminating up to 98.7% of Th (IV) and 96.5% of U(VI), with stable performance across varying concentrations. Mechanistic analyses revealed that thorium was primarily removed via adsorption onto calcium carbonate surfaces, whereas U(VI) was converted into uranyl carbonate and incorporated into the calcium carbonate lattice through co-precipitation. This study proposes an economical, efficient, and environmentally sustainable strategy for remediating aquatic environments contaminated with the radionuclides Th(IV) and U(VI).