Steel Slag as Multi-functional Material for Removal of Heavy Metal Ions in Wastewater

Removal of Cu²⁺, Cd²⁺, Pb²⁺ and Zn²⁺ in wastewater was investigated using steel slag as a treatment material, and then mechanism of removal was discussed according to main crystalline phases in steel slag and Zeta potential of steel slag. The results showed the steel slag was a very suitable multi-functional material for the treatment of wastewater containing Zn²⁺, Cu²⁺, Cd²⁺ and Pb²⁺. Under treatment conditions of the slag size of -1.0+0.5mm, slag usage of 30 g/L and stirring speed of 150rpm, initial wastewater pH value 3, reaction time of 30 min, the removal rate of Zn²⁺, Cu²⁺, Cd²⁺ and Pb²⁺ were 99.24%, 99.08%, 98.75% and 98.73%, respectively. The residual concentration of Zn²⁺, Cu²⁺, Cd²⁺ and Pb²⁺ were reduced to 0.19mg/L, 0.23mg/L, 032mg/L and 0.32mg/L from 25 mg/L concentration each in multi-metal wastewater respectively, meeting the requirements of GB 8978-1996 " Integrated wastewater discharge standard". Precipitation and adsorption were considered to be two important contributions for the removal of Cu²⁺, Cd²⁺, Pb²⁺ and Zn²⁺ in multi-metal wastewater using steel slag particles.