Integrated ultrafiltration capacitive-deionization (UCDI) for enhanced antifouling performance and synchronous removal of organic matter and salts

The crises of water scarcity and energy shortage evoked a desire for compact and energy-efficient water treatment technologies. The present study proposed a novel integrated ultrafiltration capacitive-deionization (UCDI) process, which achieved a simultaneous removal of organic matter and inorganic salts from wastewater. The organic matter was removed through size exclusion (by the ultrafiltration component) and/or electro-catalytic oxidation, while the inorganic salts were retained via electrosorption by the CDI component. Systematic experiments were conducted to investigate the UCDI behavior. Consequently, the UCDI process achieved an enhanced antifouling performance in both the ultrafiltration and CDI aspects. Besides, the organic matter facilitated the removal of Ca2+- and Mg2+-based ion pairs probably via complexation interaction, but hindered the electrosorption of Na+- and K+-based ion pairs due to site competition. During the desalination, the UCDI system could achieve an up to 100% removal of foulants through electro-catalytic oxidation, suggesting promising applications in various areas.