Effective degradation of refractory organic pollutants in landfill leachate by electro-peroxone treatment

• Landfill leachate concentrate is effectively treated by a novel E-peroxone process.
• E-peroxone process combines ozonation with electrolysis to drive peroxone reaction.
• H2O2 is electro-generated in situ from O2 in sparged gas from an ozone generator.
• Hydroxyl radicals are produced from sparged O3 and electro-generated H2O2.
• Refractory organic pollutants can be effectively mineralized in E-peroxone process.

A novel electrochemically driven process (E-peroxone) was employed to treat landfill leachate concentrates that were generated from reverse osmosis of biologically pretreated leachate. In the E-peroxone system, O3 was produced from O2 using an ozone generator. The O2 and O3 gas mixture from the ozone generator was then sparged into a reactor that had a carbon–polytetrafluorethylene (carbon–PTFE) cathode, which can convert O2 to H2O2 effectively. The in situ generated H2O2 then reacted with the sparged O3 to produce a very powerful oxidant OH, thus achieving synergy of O3 and H2O2 (i.e., peroxone) on organic pollutant degradation. Up to 87% of the total organic carbon (TOC) was removed from the leachate concentrates after 4 h of the E-peroxone process. In comparison, ozonation, conventional peroxone (using externally added H2O2), and electro-Fenton treatment removed only 45%, 65%, and 71% TOC, respectively, under similar reaction conditions in 4 h. The results indicate that the E-peroxone process may provide a convenient and effective alternative to conventional advanced oxidation processes for degrading refractory organic pollutants in wastewater.

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