Mixed industrial wastewater treatment by combined electrochemical advanced oxidation and biological processes

Nowadays, because the quality and quantity of mixed industrial wastewater keep fluctuating in recent times, the treatment of mixed industrial wastewater has gained more attention. The main target of this study is to degrade the wastewater through a combination of electrochemical advanced oxidation processes (EAOPs) and biological treatment. To enhance the biodegradability of the wastewater, Electro-Fenton process, along with external persulphate addition, was applied before the biological treatment. The effect of voltage, catalyst concentration and persulphate dosage was studied. The optimized conditions selected for the experiments were pH-3, effective area-25 cm2, electrode spacing-1 cm while voltage-10 V, persulphate dosage-200 mg L−1, and catalyst dosage-10 mg L−1 were optimized during the experiments leading towards 60% of COD removal efficiency in course of 1 h of electrolysis. Addition of tert-butyl alcohol and ethanol revealed the existence of sulphate and hydroxyl radicals as the major oxidants that help in pollutant degradation by combining EAOPs and biological treatment. Overall 94% COD removal efficiency was achieved. Therefore, for the organic pollutant degradation, combined process serves to be an efficient and effective treatment option. •Treatment of mixed industrial wastewater.•Electrochemical advanced oxidation process improved the biodegradability.•Persulphate addition enhanced the performance of electro-Fenton process.•Combined EAOPs and biological process removed 94% of COD.