Simultaneously promoted reactive manganese species and hydroxyl radical generation by electro-permanganate with low additive ozone.

• Electrolysis, permanganate, and O3 showed a satisfactory synergistic effect for various organics degradation. • Reactive manganese species (RMnS) and · OH were the dominant reactive species in E-PM-O3 process. • 1 mg L − 1 gaseous ozone dramatically promoted generating both RMnS and · OH with even lower energy consumption. • In situ formed MnO2 played a critical role for generating both RMnS and · OH. • · OH generated by O3 catalysis transfer colloid MnO2 to free mn (Ⅴ) and mn (Ⅵ) in the E-PM-O3 process. A novel water treatment process combining electrolysis, permanganate and ozone was tested in the laboratory. The combination showed synergistic effects in degrading various organic contaminants (like diclofenac, sulfamethoxazole, carbamazepine, etc.). A small amount of O 3 (1 mg L −1, 60 mL min−1) significantly improved the oxidation and mineralization ability of an electro-permanganate process by generating more reactive manganese species and hydroxyl radicals. The combination required less energy consumption than comparable processes. Mechanism experiments showed that the · OH involved was mainly generated by cathode reduction, homogeneous manganese catalysis, and heterogeneous manganese catalysis of O 3 decomposition. Reactive Mn species were generated by electro-reduction, · OH oxidation or/and O 3 activation. In situ generated Mn (Ⅳ) s plays a vital role in generating · OH and reactive Mn species. · OH generated by O 3 catalysis could transfer colloid Mn (Ⅳ) s to free Mn (Ⅴ) aq and Mn (Ⅵ) aq. And both the · OH and RMnS played the dominant role for DCF removal. Increasing permanganate dosage, O 3 concentration, the current density, C l − , or humic acid, and decreasing the pH all enhanced the degradation of diclofenac, but the presence of PO 4 3 − or HCO 3 − inhibited it. Supplementing electrolysis with permanganate and O 3 might be a practical, sustainable, and economical technology for treating refractory organics in natural waters. Image, graphical abstract [ABSTRACT FROM AUTHOR]