Novel Ecomf System: In Situ Ferrate Generation for Contaminant Removal and Fouling Mitigation in Brackish Water Desalination

Abstract

The persistent presence of contaminants of emerging concern (CECs) and severe membrane fouling remain critical challenges in the desalination of micro-polluted brackish water, necessitating innovative solutions for brackish water treatment. This study proposes, for the first time, an electrocoagulation-electrocatalytic oxidation-membrane filtration (ECOMF) system based on in-situ generation of ferrate (FeIV/V), which synergistically addresses membrane fouling and CECs removal. By integrating electrocoagulation (EC), electrocatalytic oxidation (EO), and conductive membrane filtration, the system enables simultaneous oxidation, coagulation, and fouling mitigation. At an optimal current density ratio (iEC:iEO=1:3), the ECOMF system achieved 96.0% removal of carbamazepine (CBZ), 65.8% dissolved organic carbon (DOC) reduction, and 71.8% UV254 elimination. EEM demonstrated >90% removal of protein-like and humic-like substances, attributed to FeIV/V-mediated oxidation and coagulation. Floc characterization revealed the formation of hydroxyl-rich γ-FeOOH and green rust, enhancing charge neutralization and coagulation efficiency. Through synergistic oxidation-coagulation, cathodic electrostatic repulsion, and hydrogen bubble scouring, the system reduced transmembrane pressure (TMP) by 89% and membrane resistance to 9.0×1010 m-1. Compared to conventional technologies, the ECOMF system exhibited superior performance with an operational cost of 0.113 ¥/m3. This work provides a cost-effective and sustainable strategy for the treatment of slightly polluted brackish water.

Keywords: In Situ Ferrate Generation, electrocoagulation, electrocatalytic oxidation, Membrane cathode, Coupling system