Synergistic U(VI) immobilization by a ternary Shewanella putrefaciens–chlorite–humic acid system: coupled adsorption and bio-reduction

This study aimed to enhance U(VI) removal from water by constructing a ternary system of Shewanella putrefaciens ( S. putrefaciens ), chlorite, and humic acid (HA). The ternary system achieved significantly higher U(VI) immobilization than single or binary systems, owing to synergistic effects of adsorption enrichment, electron shuttling, and bioreduction. Under optimal conditions, the U(VI) removal efficiency reached 91.6%. Importantly, pre-forming the ternary composite before U(VI) addition avoided false removal caused by HA-U(VI) complexation, ensuring accurate assessment of reductive immobilization. This work provides a reliable strategy for uranium-contaminated water remediation. Graphical abstract