Comprehensive Study of Different Multifunctional Membranes with Fenton Oxidation and Ultrafiltration for Real Industrial Wastewater Treatment

Integrating catalytic oxidation and ultrafiltration in multifunctional membranes seems a promising method to strengthen wastewater treatment, and multiple strategies developed for further enhancement of multifunctional membranes have been focused upon recently. However, a comprehensive evaluation of multifunctional membranes and their strengthened variants compared with separate oxidation and ultrafiltration units using real industrial wastewater is still absent. In this study, a traditional multifunctional membrane and multifunctional membranes strengthened by catalyst enhancement, catalyst loading enhancement, and oxidation/ultrafiltration sequence optimization were synthesized for the real industrial wastewater treatment, compared with separate units of oxidation and ultrafiltration. The membrane structure was characterized by various methods, treatment efficiency and membrane fouling were evaluated, and stability for long-term operation was investigated by analysis of the decontamination performance decline and membrane characterization. The results indicate that direct immobilization of the catalyst in an ultrafiltration membrane might sacrifice the decontamination performance. Strengthening the multifunctional membrane by catalyst activity and catalyst loading enhancement could improve decontamination and antifouling performance, while it would reduce the stability due to high oxidative activity on the membrane matrix. Optimizing the sequence of ultrafiltration before catalytic oxidation in the multifunctional membrane could efficiently improve the treatment efficiency and stability, while the antifouling performance would be weakened greatly. Multifunctional membrane development can strengthen wastewater treatment indeed in some respects, but their shortcomings should be carefully considered as well. We believe this study gives a new understanding on multifunctional catalytic oxidation and ultrafiltration membrane-based systems, and provides guidance regarding their practical application for wastewater treatment.