Membrane-aerated Electro-Fenton system for nanofiltration concentrate treatment: hydrogen peroxide generation enhanced and carbon dioxide stripping control

Conventional electro-Fenton (EF) systems suffers from oxygen supply limitations due to low O₂ solubility and bubble-controlled triple-phase boundaries. We propose a membrane-aerated electro-Fenton (CF-MA) reactor that delivers O₂ directly at the solid-liquid interface to enhance in-situ H₂O₂ formation and mass transfer. The CF-MA system exhibited a volumetric gas–liquid mass-transfer coefficient (K_La) of 0.087 min⁻¹ and produced 95.6 mg L⁻¹ H₂O₂ at an aeration rate of 25 mL min⁻¹. Compared with solution-aerated electro-Fenton (CF-SA), the CF-MA system increased the removal efficiencies of atrazine (ATZ), sulfamethoxazole (SMX), benzoic acid (BA), and carbamazepine (CBZ) by 22.4–31.7 %, and achieved 47.1 % total organic carbon (TOC) removal for real nanofiltration (NF) concentrate. Under the optimal condition (5.0 mA cm⁻² current density and 60 min reaction time), the CF-MA showed a specific energy consumption of 0.67 kWh g⁻¹ TOC removed, indicating favorable energy efficiency and engineering feasibility. Moreover, experimental results indicate that the CO₂ emissions of the CF-MA system are only 1/17th of those of the CF-SA system, highlighting the dual benefits of enhanced pollutant removal efficiency and reduced carbon footprint.