Efficient removal of organic pollutants in reverse osmosis concentrate by coupling granular activated carbon adsorption with ozone

• Coconut shell-activated carbon (CGAC) shows efficient adsorption performance for organic matters in reverse osmosis concentrate (ROC). • The ozone could efficiently regenerated and recycled CGAC. • CGAC/O 3 system is a novel strategy for ROC remediation. The advanced removal of organic pollutants from reverse osmosis concentrate (ROC) remained challenging due to the limitations of cost-efficiency in conventional treatment processes. This study proposed a novel integrated approach combining granular activated carbon (GAC) adsorption with ozone regeneration (GAC/O₃) for effective ROC remediation. The process involved two sequential stages: (1) adsorption of organic pollutants onto GAC until saturation, followed by (2) ozone-induced degradation of the adsorbed contaminants through in-situ regeneration. Continuous-flow experiments demonstrated that the hybrid GAC/O₃ system achieved a 63.6 % reduction in dissolved organic carbon (DOC) concentration (from 44.18 mg/L to 16.09 mg/L) over five consecutive cycles, with ozone consumption significantly reduced by 10.9-fold (4.9 mg O₃/mg DOC) compared to standalone ozonation. Mechanistic analyses revealed that organic pollutant adsorption was dominated by π–π interactions between aromatic moieties and pore-filling effects. The oxygen-containing groups on the surface of GAC, phenolic hydroxyl and carboxyl group, were used to active O 3 to form hydroxyl radical for the adsorbed organic pollutants destroyed. This work provided a theoretical foundation for the GAC/O₃ system as a sustainable strategy to enhance ROC treatment efficiency.