Performance of the Uncoated Titanium Anode in the Chemical Oxygen Demand Removal of Industrial Wastewaters; (a Case Study on the Electrochemical Treatment of the Textile Effluent at the Pre-Pilot Scale)

In the current work, the capability of uncoated titanium anode in the electrochemical treatment of textile wastewater has been investigated with the aim of simultaneously benefiting from electrooxidation and electrocoagulation treatment processes. In the present work, the feasibility of using uncoated titanium anodes for wastewater treatment is studied in an electrochemical pre-pilot set-up with polymeric casing and an electrical supply power of 150 W, operated under galvanostatic regime in batch mode, focusing on the current density as the main subject of assessment, and its performance is evaluated using metrics such as chemical oxygen demand removal and specific energy consumption. A noticeable finding of this work, is the flexibility of the set-up to combine the electrocoagulation and electro-oxidation mechanisms with the current density as the controlling parameter, leading to a remarkable decontamination capability, so that reductions in the total chemical oxygen demand as large as 75–80% in the neutral and 90–95% in the acidic environments were achieved. At low current densities (< 100 μA/cm2), the anodic corrosion was limited and the electro-oxidation was the dominant wastewater treatment mechanism. At high current densities (> 100 μA/cm2), the anodic corrosion was accelerated and the dominant wastewater treatment mechanism was switched to electrocoagulation. Along with the chemical oxygen demand removal capability, the energetic cost-effectiveness of the set-up was a major concern, particularly from the industrial point of view, which was assessed in both neutral and acidic environments, and it was realized optimization occurred at 600 μA/cm2, so that the specific energy consumption and the rate specific energy consumption, were both minimized at this current density, in respective order, 8.9 kWh/kgCOD and 3.52 kWh/kgCOD/h in neutral, and 10 kWh/kgCOD and 2.34 kWh/kgCOD/h in acidic environments.