Adsorption of zinc, cadmium and nickel from aqueous solutions using ground water sludge (GWS)

In this study, the applicability of ground water sludge (GWS), a waste material from a ground water treatment plant as a potential absorbent for heavy metals was experimentally analyzed. The presence of 56.4% of Fe ₂O₃ in the GWS composition indicated that GWS has potential adsorptive behaviour. An adsorption study using GWS was performed and results were analyzed in the adsorption of several heavy metals namely Ni, Cd, and Zn. The adsorbent concentrations (GWS) were varied from 250 mg/L to 4000 mg/L and agitated with aqueous heavy metal solutions for 1hr, 3hrs, 6hrs and 24hrs contact times. The batch adsorption indicated that Ni, Cd, and Zn were totally adsorbed using 4000 mg/L of the absorbent at a contact time of 24hrs. The removal efficiencies for Cd, Ni, and Zn at adsorbent concentrations of 3000 mg/L, 3500 mg/L and 3500 mg/L, were found to be 91.6%, 73.8% and 69%, respectively. Adsorption of metals also increased with longer contact times and higher adsorbent dosages. The study indicated that there is a potential in using waste sludge from ground water treatment plants as an adsorption material in removing heavy metals.