Integration of ultraviolet irradiation with electrochemical chlorine and hydrogen peroxide production for micropollutant abatement

This research evaluated integrating ultraviolet (UV) irradiation with electrochemical chlorine (Cl-2) and/or hydrogen peroxide (H2O2) production for micropollutant abatement in water treatment. Combining UV with anodic Cl-2 production (E-UV/Cl-2) effectively abated gemfibrozil and naproxen, but ineffectively abated ibuprofen due to its low reactivity with chlorine radicals (e.g., ClO center dot and Cl-2(-)center dot). In comparison, combining UV with cathodic H2O2 production (E-UV/H2O2) more effectively abated ibuprofen, but less efficiently abated gemfibrozil and naproxen due to the significant scavenging of center dot OH by the water matrix. Moreover, simultaneously producing Cl-2 and H2O2 during UV irradiation (E-UV/Cl-2/H2O2) in an undivided reactor did not further enhance micropollutant abatement compared to the E-UV/H2O2 process because of the mutual consumption of anodically generated Cl-2 and cathodic generated H2O2. In contrast, by separating the anodic and cathodic compartments with an anion exchange membrane and operating the E-UV/Cl-2 /H2O2 process in an anode-to-cathode configuration, all test micropollutants could be adequately abated through the sequential oxidation with the selective chlorine radicals and non-selective center dot OH in the anodic and cathodic compartments. In general, the concentrations of micropollutants could be abated by 84-100% with a short hydraulic residence time (HRT) of 9.4 min and feasible energy demand (E-EO <= 3.15 kWh/m(3) -log) in the selected groundwater and secondary wastewater during the E-UV/Cl-2/H2O2 process in the divided reactor. The results indicate that different synergistic effects can be obtained for micropollutant abatement by combining UV and electrochemical processes in varying configurations, and the divided E-UV/Cl-2/H2O2 process is a more robust and energy-efficient method for micropollutant abatement during decentralized water treatment.

Automated summary

This research evaluated the combination of UV irradiation and electrochemical processes for micropollutant abatement in water treatment, finding that the divided E-UV/Cl-2/H2O2 process was more effective and energy-efficient for removing micropollutants. The study highlights the potential synergistic effects of combining UV and electrochemical methods in different configurations for decentralized water treatment.