Performance Evaluation of Chemical Coagulation and Electro-Fenton Combined Processes Treating Real Pharmaceutical Wastewater

Background: Pharmaceutical wastewater mainly contains high levels of organic matter. In order to produce a suitable wastewater for discharge into the municipal sewage, chemical and electrochemical methods have been studied. The aim of this study was to evaluate the efficiency of chemical coagulation/electro-Fenton combination process in chemical oxygen demand (COD) reduction of pharmaceutical wastewater. Methods: The effect of Poly aluminum chloride (PAC) concentration 25-300 mg/L and pH of 3-7-10 were investigated. The effluent of chemical coagulation stage was transferred to the electro-Fenton stage. Further, the effect of H2O2 concentration 100 - 4000 mg/L, contact time of 15-120 min, voltage of 10-30 v and pH of 3-10 were investigated. Results: The results showed that the highest removal rate of COD was 93.5% in the optimal conditions at coagulant dose 200 mg/L and pH of 7 for the coagulation process, and at concentration of 100 mg/L hydrogen peroxide, the voltage of 20, pH of 3 and contact time of 30 min for the electro-Fenton process (EFP). The results showed that chemical and electrochemical processes are effective methods for the pharmaceutical wastewater treatment. Conclusion: It is generally concluded that combined processes are more effective than the coagulation process alone in removing organic compounds from pharmaceutical wastewater.