Removal enrichment and recovery of Ni(II), Zn(II) and phosphate from phosphation rinsing waters with liquid-phase polymer-based retention technique

The removal enrichment and recovery of Ni(II), Zn(II) and phosphate with liquid-phase polymer-based retention (LPR) was studied on a laboratory level and on a pilot scale with real wastewater. Hyperbranched poly(ethylenimine) (HBPEI) was used, in favour, as complexing and ion exchange agent. Sorption behaviour and loading capacities of the polymer with respect to Ni(II), Zn(II), Mn(II) and phosphate were studied under various conditions in order to implement the system into a pilot unit for the treatment of industrial phosphation rinsing waters. The recovery of Ni(II) and Zn(II), accomplished in that pilot unit, constantly reached values over 99%. Starting from an initial metal concentration of around 20 mg l−1 enrichment up to 1000 mg l−1 for Ni(II) and Zn(II) was achieved. At the same time the heavy metal concentration of the discharge water always remained below the German discharge limits of 0.5 mg l−1 Ni(II) and 2 mg l−1 Zn(II), respectively. Phosphate anions were also enriched and partially recovered.