Fluid catalytic cracking waste slag-enhanced sulfate-reducing bacteria for efficient remediation of Cd/Zn pollution...

This study presents a combined remediation approach using fluid catalytic cracking (FCC) waste slag and sulfate-reducing bacteria (SRB) for Cd and Zn pollution in non-ferrous smelting site soils. In simulated solution systems, the FCC slag-enhanced SRB system achieved over 99 % removal of Cd and Zn within 5 days, outperforming individual treatments. Mechanistic analysis showed that FCC waste slag reduced metal toxicity through adsorption, creating a more favorable environment for SRB activity. Sulfate reduction by SRB generated sulfide, promoting metal sulfide precipitation and forming a stable mineral film. In soil column experiments, Cd and Zn concentrations in leachate dropped below Class IV groundwater standards within 28 days, with inhibition rates of 90.05 % and 92.12 %, respectively. High-throughput sequencing revealed significant microbial succession: the relative abundance of Desulfitobacterium increased to 11.77 % and 11.87 % on days 28 and 56, while acid-producing genera were suppressed. This synergistic system enhances remediation efficiency and ecological stability, offering a practical solution for multi-metal-contaminated soil remediation.