Highly Cost-Effective and Reuse-Oriented Treatment of Cadmium-Polluted Mining Wastewater by Electrocoagulation Process

Abstract

This study investigated the efficiency and cost-effectiveness of electrocoagulation (EC) parameters using aluminum (Al) electrodes to remove cadmium (Cd) from synthetic and real industrial mining wastewater (MWW) discharged by the Tunisian Chemical Group (TCG), which poses serious ecological hazards. Based on individual examinations of each operation parameter, the best removal of Cd was obtained at a current density of 7.35 mA cm−2, an initial pH of 7, and a sodium chloride (NaCl) dose of 2 g L−1 corresponding to a conductivity of 5.3 mS cm−1. The effects of initial concentrations, the Faradic efficiency, the state of the Al plates, the electrical energy consumption, and the operating cost were examined in detail. These optimum conditions enabled the achievement of a largely efficient removal in a relatively short treatment time of 30 min, with a significantly low operating cost of 0.2 Tunisian national dinars (TND) m−3; a low energy consumption of 0.5 kWh m−3 yielded the total removal of Cd. In addition, an application of all the optimum EC parameters together was carried out; a total removal was achieved not only of Cd, but also of other pollutants, at the same time. The investigation of EC processes carried out in this work provides evidence for a highly cost-effective wastewater treatment method if compared to other widely used technologies such as coagulation and precipitation.