Electrochemical pretreatment enhances RO performance: Extending membrane lifespan while reducing concentrate volume

Industrial circulating cooling water, characterized by high salinity and complex pollutants, accelerates reverse osmosis (RO) membrane fouling and increases concentrate (ROC) production, hindering near-zero wastewater discharge. This study proposes an electrochemical-induced crystallization-RO (EC-ICC-RO) coupling process. Through parameter optimization and mechanism analysis, we demonstrate that EC pretreatment synergistically controls fouling by: (1) electrochemical softening to reduce scaling ions (e.g., Ca²⁺, Mg²⁺), (2) electrocatalytic oxidation to degrade organic foulants, and (3) electrochemical disinfection to inactivate microbes. This coupled process mitigates membrane fouling and enhances process efficiency. In continuous-flow experiments (hydraulic retention time: 14.4 min; voltage: 6 V; electrode spacing: 1 cm), the RO membrane lifespan reached 1352 min—a 203 % increase versus the non-pretreated group. Water production energy consumption dropped to 8.6 × 10⁻¹ kWh·L⁻¹, with a 63 % lower flux decline rate. The ICC stage utilizes porous activated carbon for early-scale deposition via heterogeneous adsorption, reducing RO inorganic load while lowering residual chlorine to prevent membrane damage. The EC-ICC-RO process is cost-effective (operational cost: 0.1729 CNY·L⁻¹, about 80 % reduction vs. conventional RO) and chemical-free, enabling balanced pollutant removal, membrane longevity, and energy efficiency. This technology provides an efficient, low-carbon solution for near-zero discharge of industrial cooling water.