Intensification of electrocoagulation treatment of simulated tannery wastewater using rotating electrodes: Parametric, isotherms, kinetic and techno-economic studies

This research work aims to intensify the electrocoagulation (EC) treatment of synthetic/simulated tannery wastewater using a reactor with a rotating anodes and cathode rings connected in a monopolar-parallel manner for the efficiently removal of COD and Cr (VI). In this study, important EC operational parameters including rotating anode speed [50–300 rpm], pH [2.0–12.0], electrolysis time [5–30 min] and current density [0.53–3.18 mA/cm²] are varied and their efficacy on EC treatment is evaluated. The maximum reduction of COD and Cr(VI) are obtained as 91 % and 95 %, respectively, with the optimized conditions as speed = 100 rpm, pH = 6, time = 20 min and current density = 2.65 mA/cm². Isotherms and Kinetics studies for both the COD and Cr(VI) removal are also performed and to analyse the best fit kinetics (pseudo second-order with R² = 0.97 and the intra-particle diffusion with R² = 0.99, respectively) and isotherm models (Sips with R² = 0.99 and Freundlich with R² = 0.98, respectively) along with appropriate model parameters. Lastly, the electrical energy consumption (EEC = 1.77 kWh/m³), electrode consumption (ELC = 0.075 kg/m³), stirrer energy consumption (SEC = 0.043 kWh/m³) and operating cost (OC = 0.36 US $/m³) under optimal conditions are calculated.