Heavy Metal Removal in the Presence of Colloid-Stabilizing Organic Material and Complexing Agents

Abstract

It has been established in laboratory model experiments that the removal of dissolved heavyimetals from wastewaters is rendered more difficult in the presence of colloid-stabilizing agents. This unfavourable effect can be eliminated by the addition of Mg2+ ions and the adjustment to a fairly high pH. By increasing the concentration of Mg2+ ions, the pH necessary for destroying the stability of colloidal dispersion can be lowered. These findings also apply to the combined removal of different heavy metals (Cu, Zn, Cr(III), Ni, Cd). In alkaline conditions, in the presence of ammonium salts, some heavy metals (Cu, Zn, Ni) form high stability amine complexes. A higher pH is necessary for the breakdown of these complexes and the satisfactory removal of heavy metals.