Efficiency of Removing Chromium from Plating Industry Wastewater using the Electrocoagulation Method

Aims: Chromium is one of the most important metallic pollutants in plating industry wastewater. This toxic metal poses serious threats to human health and to the environment due to its cumulative effects and non-degradability. This research intended to study the effects of the pH, contact time, and voltage parameters on the degree of chromium removal from plating industry wastewater by the electrocoagulation method. Materials and methods: A 1000-cc reactor at laboratory scale was used that included 4 aluminum electrodes of 90% purity, dimensions of 5 by 10 cm, and thickness of 1 mm, had a parallel arrangement, and were directly connected to a power source unit (PSU) for converting alternative current to direct current. Synthetic chromium-bearing wastewater was prepared at the initial concentration of 50 mg/l, pH values of 3, 7, and 9, electric potentials of 20, 30, and 40 volts. Process durations were 20, 40, 60, and 80 minutes. Findings: The maximum and minimum chromium metal concentrations remaining in the synthetic wastewater after the electrocoagulation process were 18.5 and 0.65 mg/l, respectively. The highest chromium removal efficiency was 98.7% (achieved at pH=3, contact time of 80 minutes, and voltage of 40 volts), and the minimum 63% (observed at pH=9, contact time of 20 minutes, and voltage of 20 volts). Conclusion: Results indicated the electrocoagulation method was an efficient, economical, and useful technology for removing or reducing chromium in toxic wastewater of plating industry.