Treatment of metal containing wastewaters by natural zeolites

Abstract

In this study, removal of heavy metals in synthetic and wastewaters was studied by using natural zeolite, clinoptilolite. The activated and non-activated zeolites used were crushed and grinded to sizes between 1.0-2.0 mm. Ion exchange studies were conducted as batch experiments for various mixing time, speed and different concentrations of Pb2+, Cd2+, Ni2+, and Zn2+. Gordes and Bigadic zeolites were used for Cd2+ and Ni2+ removal and their efficiencies were compared with that of natural zeolites from different areas. Although Cd2+ was not removed effectively by Bigadic zeolite, in applying Gordes zeolite 46% removal efficiency was achieved for 90 min of contact time in batch tests. Column studies were performed for the removal of Pb2+, Cd2+, and Zn2+ from a lead-zinc mining process raw wastewater. The clinoptilolite exhibited about 100%, 98%, and 96% removal efficiency for Pb, Zn2+, and Cd2+, respectively. The overall adsorption capacity for Bigadic clinoptilolite was around 23 mg Pb2+/g, 24 mg Zn2+/g, and 0.6 mg Cd2+/g.