Application of EICP Technology in the Remediation of Lead- and Zinc-Contaminated Sand and Improvement of Its Mechanical Properties

This study investigated the effectiveness of enzyme-induced carbonate precipitation (EICP) technology in remediating Pb- and Zn-contaminated sand. The research focused on the immobilization of heavy metals and the enhancement of sand strength. Experimental results demonstrated that urease activity increased linearly with enzyme concentration, stabilizing at 100 g/L with an activity of 18 mmol/min, and reached a peak at a pH of 8. Temperature variations also positively impacted urease activity, and effective remediation levels were achieved at standard room temperature. The EICP method effectively transformed heavy metal ions from a mobile exchangeable state to a stable carbonate-bound state, and removal rates exceeded 80% for Zn2+ and 90% for Pb2+ after three treatment cycles. Furthermore, the technology significantly improved the unconfined compressive strength of contaminated sand, increasing Pb-contaminated sand strength to 0.57 MPa and Zn-contaminated sand strength to 0.439 MPa. These findings highlight the potential of EICP technology as a viable solution for the remediation of heavy metal–contaminated sand, offering both immobilization of contaminants and enhancement of sand mechanical properties.