Application of the electrocoagulation technique for treating heavy metals containing wastewater from the pickling process of a billet plant

摘要

This work was carried out to study the removal of various heavy metals, including Cu, Cr, Pb and Zn, from billet industry wastewater by the electrocoagulation process in both batch and continuous experiments at a laboratory scale and ambient temperature (30℃). In the batch experiment, the effect of various parameters including the current density, initial wastewater pH and electrolysis time, on the metal removal efficiency was examined. Optimal metal ion depletion was attained with a current density of 98 A/m~2, an initial wastewater pH of 5 and a 30 min electrolysis time. Under these conditions, greater than 99% of Cu, Cr and Zn was removed, whilst the outlet wastewater contained Cu, Cr, Pb and Zn at less than 0.02, 0.01, 0.07 and 0.05 mg/l, respectively. For the continuous process, the results indicated that the treatment system reached its steady state condition within 120 min, and the optimum condition for the continuous treatment was found at an initial wastewater pH of 3 and flow rate of 55 ml/min. At this condition, a complete removal of Cu and Pb and greater than 99% removal of Cr and Zn were achieved.