Investigation of electrocoagulation reactor design parameters effect on the removal of cadmium from synthetic and phosphate industrial wastewater

Abstract

This study investigates the effect of reactor design parameters on cadmium removal from industrial wastewater discharged by the Tunisian Chemical Group (TCG) to improve as much as possible efficiency and cost of electrocoagulation (EC) process. Based on an examination of the design parameters one by one, the best cadmium removal was achieved for an inter-electrode distance (die) of 0.5 cm, monopolar connection mode, stirring speed of 300 rev min−1, surface-area-to-volume ratio (S/V) of 13.6 m−1, and an initial temperature of 50 °C. These operating conditions are allowed to achieve efficient removal in a relatively short operating time with the lowest energy consumption and cost possible. The present study proved that the parameters that have an effect on the operating cost are the electrode configuration, inter-electrode distance and S/V ratio. The energy consumption, the pH evolution, and the treatment cost were studied. The investigation of the effect of all the selected optimum EC design parameters together on the removal of cadmium from the TCG wastewater proved that the treatment was highly efficient; 100% of cadmium removal was reached in 5 min, with a very low power consumption (1.6 kW h m−3) and very low cost (0.116 TND m−3). Moreover, EC was found to be capable of removing cadmium as well as other pollutants at the same time from the case-study industrial wastewater. The investigation carried out in this work explores and proposes a very cost-effective treatment method to remove heavy metals from industrial wastewater if compared to results reported about cost of this treatment process through other widely used technologies such as coagulation (4.36 Tunisian National Dinar (TND) m−3) and precipitation (9.96 TND m−3) employed in previous studies. Keywords: Wastewater treatment, Electrocoagulation, Treatment cost, Investigation of reactor design parameters, Cadmium removal, Energy consumption