Comparison of COD removal from pharmaceutical wastewater by electrocoagulation, photoelectrocoagulation, peroxi-electrocoagulation and peroxi-photoelectrocoagulation processes

► Hydrogen peroxide improves the performance of electrocoagulation process. ► UV light can be effective on the performance on peroxi-electrocoagulation and electrocoagulation processes. ► The optimal amount of hydrogen peroxide for peroxi-electrocoagulation process for COD removal from pharmaceutical wastewater is 300 mg/L. ► The optimal values of pH for electrocoagulation and peroxi-electrocoagulation are 7 and 3, respectively.