Remediation of As and Sb co-contaminated mine runoff by a pilot-scale aboveground permeable reactive barrier filled with multiple solid wastes-based reactive media

Mine runoff, characterized by its dispersion, fugitive discharge and coexistence of dissolved- and particulate-heavy metals, pose substantial challenges to conventional wastewater treatment methods ( e.g. , chemical precipitation) that require wastewater collection and frequent manual maintenance. Herein, we propose a maintenance-free and effective in-situ approach by utilizing an aboveground permeable reactive barrier (APRB) filled with multiple solid waste-based reactive media (MSRM) for mine runoff remediation. The pilot-scale APRB, operating at a high influent flow rate (1 L/min) for 360 h, maintained removal rates exceeding 65.02 %/62.27 % for dissolved-As/Sb from mine runoff, followed by exhaustion times of 1198.20/1334.44 h, respectively. Meanwhile, significant removal rates of over 96.47 %/87.31 % were achieved for particulate-As/Sb, respectively. The effective removal of As/Sb from mine runoff was attributed to the synergistic effects of adsorption, precipitation and micro-electrolysis within MSRM, alongside gravity sedimentation of suspended particulate matter (SPM) facilitated by the APRB. Our findings provide a cost-effective strategy for the large-scale remediation of unregulated and SPM-rich mine runoff. • MSRM-filled APRB was proposed for maintenance-free remediation of mine runoff. • Simultaneous removal of dissolved- and particulate-As/Sb was achieved. • Long-term efficiency benefit from hydration and micro-electrolysis of solid wastes. • Gravity sedimentation of SPM in APRB enhanced particulate-As/Sb removal.