The performance of electrochemical peroxidation process for COD reduction and biodegradability improvement of the wastewater from a paper recycling plant

• Electrochemical peroxidation process was examined to treat wastewater from a paper recycling plant.
• Electrochemical peroxidation process reduced 95.7% of COD at optimized conditions at a reaction time of 30 min.
• Electrochemical peroxidation process increased biodegradability to a level suitable for biological post-treatment.
• Electrochemical peroxidation process is a promising technique for reclaiming wastewater from paper recycling.

This study investigated pretreatment and biodegradability of wastewater from a paper recycling plant using the electrochemical peroxidation process in a bench scale reactor. The influence of wastewater pH, H2O2 concentration, current density, and reaction time was evaluated for the removal of COD from the wastewater. The COD of wastewater from paper recycling decreased from the initial level of 4300 mg/L in raw wastewater to 106 mg/L (95.7% removal) in wastewater treated by the electrochemical peroxidation process at optimum pH, H2O2 concentration, current densities of 4, 15 and 5 mA/cm2, and a reaction time of 30 min. The optimum ratio of H2O2 (mM) to Fe2+ (mM) was found to be 2. The biodegradability of wastewater increased from an initial level of 0.12 to 0.43 after treatment by the electrochemical peroxidation process under optimum experimental conditions at a reaction time of 30 min. Overall, the electrochemical peroxidation process proved to be an efficient and appropriate technique for COD reduction and enhancement of biodegradability of the industrial effluents containing high concentrations of recalcitrant organic compounds.