Harnessing biomineralization-flotation technology for efficient recovery of lead from contaminated water and soil

While microbial-induced carbonate precipitation (MICP) immobilizes heavy metals (HMs), the resulting precipitates are often susceptible to remobilization under extreme pH conditions. This study evaluated an integrated MICP-flotation technology as a sustainable strategy for recovering lead (Pb) from contaminated water and soil. By optimizing inoculation ratios, pulp pH, aeration rates, and reagent combinations, supported by molecular dynamics (MD) simulations, the study identified mechanistic drivers of recovery efficiency. While high inoculation ratios impeded Pb recovery, increased pulp pH and aeration rates significantly enhanced performance. In aqueous systems, the synergistic use of cationic collectors and foaming agents achieved a Pb recovery of 85.8%. These reagents initially maintained stability through electrostatic repulsion before increasing mineral hydrophobicity to facilitate bubble adhesion. In soil applications, untreated loess exhibited positive surface charges that repelled cationic collectors, hindering recovery. However, MICP treatment transformed Pb into cerussite (PbCO 3 ), which possesses a negative surface charge. This shift promoted electrostatic attraction with cationic reagents, yielding a recovery efficiency of 84.5%. These findings indicate that MICP-flotation integrated technology is a sustainable approach for the recovery of HMs from complex environmental matrices.