An integrated approach for simultaneous immobilization of lead in both contaminated soil and groundwater: Laboratory test and numerical modeling.

In this study, we demonstrated the feasibility of an integrated remediation approach for simultaneous immobilization of Pb in both soil and groundwater. The laboratory test was conducted via column experiment by pumping Pb-contaminated groundwater into the pre-amended contaminated surface soils to identify their retention and immobilization ability of Pb. HYDRUS modeling was undertaken to simulate Pb distribution and permissible treatment capacity in the remediation. The experiment results showed that phosphate- and biochar-amended soils were highly effective in removing Pb from contaminated groundwater, with the removal reaching up to 94.2% and 84.5%, respectively. However, phosphate amendment was more effective in immobilizing Pb with TCLP extracted Pb reduced by 18.3%-51.5%, compared to the control, while the reduction for biochar amendment was less than 13.5%. The modeling indicated that phosphate-amended soil could immobilize 509gPbm-2 soil under the environmentally-relevant conditions, given both groundwater and soil quality criteria being met. Our study demonstrated that the integrated system with phosphate amendment is fairly feasible for simultaneous remediation of both Pb-contaminated soil and groundwater.