Enhancing membrane distillation efficiency in treating high salinity organic wastewater: A pressure-driven membrane electrochemical reactor approach

Abstract

Fouling of membranes continues to be a prominent challenge in the membrane distillation (MD) treatment of high salinity organic wastewater (HSOW). Although membrane electrochemical reactor (MER) can effectively inhibit the membrane fouling of MD, the high cost of the proton exchange membrane (PEM) used in MER limits its widespread application. In this study, cost-effective pressure-driven membranes were employed as a substitute for PEM to establish pressure-driven membrane electrochemical reactors for HSOW pre-treatment. By using ultrafiltration membrane (UFM) and reverse osmosis membrane (ROM), UFMER and ROMER were developed, respectively. Due to the superior electrochemical performance of UFM, UFMER saved 43 % of energy compared to PEMER with the highest removal rate of organics (~85 %) in the simulated HSOW treatment. In practical applications, using UFMER significantly reduced the amount and size of complexes in the real nanofiltration concentrate (NC) of landfill leachate. This contributed to the superior specific flux maintenance (97 %) with a salt rejection (>99 %) and the highest recovered specific water flux (99.6 %) in MD cases. UFMER reduced ~27 % of energy compared to PEMER in MER pre-treatment, and saved the most energy (~39.6 %) in MD post-treatment. Hence, this strategy is potential for forthcoming applications, notably in lowering the membrane cost of MER and energy consumption of both MER and MD.