Electrochemical treatment of biologically pre-treated dairy wastewater using dimensionally stable anodes

In this work, electrochemical oxidation of aerobically pre-treated dairy wastewaters using IrO₂-Pt coated dimensionally stable anodes was investigated. It was found that IrO₂/Ti electrode outperforming Pt/Ti and IrO₂-Pt/Ti at lower current densities, while Pt/Ti achieved better efficiency at higher current density. Among the different parameters which were studied, the current density was the most crucial for the efficiency of the process. A current density of 100 mA/cm² led to almost complete removal of 3700 mg/L COD after 360 min of treatment using IrO₂/Ti electrode and 0.2 M of sodium chloride while complete decolorization was achieved in less than 60 min. Electrolytes also found to significantly affect the process. More specific, the use of sodium chloride instead of sodium sulfate enhanced both COD and color removal due to the formation of active chlorine species. The effect of temperature was relative low; the process was favourable at elevated temperatures while increasing COD loading resulted in a decrease of COD and color removal.