Electrocoagulation coupled with conductive ceramic membrane filtration for wastewater treatment: Toward membrane modification, characterization, and application

Abstract

Membrane separation is an effective solution for pollutant removal, however, achieving high permeability and antifouling ability remains a pressing challenge for its widespread application. In this study, a novel method of coating flat ceramic membranes (CMs) with a conductive film (Sb-SnO2) was developed to enhance the filtration and antifouling performance of CMs when the membrane filtration was coupled with electrocoagulation. After comparing the parameters, including the film sheet resistance and pure water flux, with those of other coating methods (i.e., gel coating and immersion hydrolysis), a well-fixed conductive coating with optimal permeability and stability was generated using spray pyrolysis with a substrate ceramic membrane surface temperature of 475 °C, precursor concentration of 0.5 M (calculate as SnO2), and spraying amount of 50 mL (120 cm2), during membrane modification. Batch filtration experiments using wastewater from the mechanical industry demonstrated that the conductive ceramic membrane (CCM) cathode integrated with electrocoagulation at an electric field of 2.8 V/cm (3.0 mA/cm2) achieved permeate fluxes that were 0.34, 0.70, 0.75 and 1.41 times higher than those of sole CM separation after four cycles. Moreover, the membrane separation process was dominated by the standard pore-blocking model, and its correlation coefficient decreased with the exertion of the electric field, indicating that membrane filtration fouling changed from irreversible to reversible. This CCM combined with electrocoagulation exhibited significant potential for alleviating membrane fouling and widespread application, and could act as a promising technology for industrial wastewater treatment.