Simultaneous As(III) and Cd removal from copper smelting wastewater using granular TiO₂ columns.

Remediation of metallurgical industry wastewater has presented a great environmental challenge for decades. In this study, a complete remediation technology was proposed for simultaneous As(III) and Cd adsorptive removal, adsorbent regeneration, and recovery of As and Cd. Using three granular TiO₂ columns in series, As(III) and Cd in the raw water at 2590 ± 295 and 12 ± 2 mg/L, respectively, could be reduced to 0.16 ± 0.11 and 0.0133 ± 0.0134 mg/L, well below the wastewater discharge limit. Spent TiO₂ media could be regenerated using H₂SO₄ and NaOH, and the regenerated adsorbent could be re-used for at least 10 treatment cycles and 770 bed volumes with no decrease in its adsorption capacity. Remediation of 1 L wastewater generated 0.89-1.5 g solid residue which could be used as an intermediate for the As and Cd chemical refinement. The waste solution can be further treated after mixing with raw water to adjust the raw pH from 1.4 to 7. This adsorption, regeneration, and reuse process provides an innovative technology for metallurgical industry wastewater remediation that is promising for practical application.