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Pilot-scale evaluation of micropollutant abatements by conventional ozonation, UV/O3, and an electro-peroxone process

Yao, Weikun, Ur Rehman, Syed Waqi, Wang, Huijiao, Yang, Hongwei, Yu, Gang, Wang, Yujue
Water research 2018 v.138 pp. 106-117
chloramphenicol, clofibric acid, diclofenac, energy efficiency, energy use and consumption, gemfibrozil, groundwater, hydrogen peroxide, hydroxyl radicals, ibuprofen, oxidation, ozonation, ozone, persistent organic pollutants, surface water, ultraviolet radiation, wastewater, wastewater treatment
The electro-peroxone (E-peroxone) process is an emerging ozone-based advanced oxidation process (AOP) that has shown large potential for micropollutant abatement in water treatment. To evaluate its performance under more realistic conditions of water treatment, a continuous-flow pilot E-peroxone system was developed and compared with conventional ozonation and a UV/O3 process for micropollutant abatements in various water matrices (groundwater, surface water, and secondary wastewater effluent) in this study. With a specific ozone dose of 1.5 mg O3/mg DOC, micropollutants that have high and moderate reactivity with ozone (O3) (diclofenac, naproxen, gemfibrozil, and bezafibrate) could be sufficiently abated (>90% abatement) in the various waters by all three processes. However, ozone-resistant micropollutants (ibuprofen, clofibric acid, and chloramphenicol) were abated only by ∼32–68%, 68–91%, and 73–90% during conventional ozonation of the selected groundwater, surface water, and secondary wastewater effluent, respectively. By electro-generating H2O2 or applying UV irradiation to enhance O3 transformation to •OH during ozonation, the E-peroxone and UV/O3 processes similarly enhanced the abatement efficiencies of ozone-resistant micropollutants by ∼15–43%, ∼5–15%, and ∼5–10% in the groundwater, surface water, and secondary wastewater effluent, respectively. In addition, the E-peroxone and UV/O3 processes significantly reduced bromate formation during the treatment of the three waters compared to conventional ozonation. Due to its higher efficiency, the E-peroxone process reduced ∼10–53% of the energy consumption required to abate the concentration of chloramphenicol (the most ozone-resistant micropollutant spiked in the waters) by 1 order of magnitude in the three waters compared to conventional ozonation. In contrast, the UV/O3 process consumed approximately 4–10 times higher energy than conventional ozonation. This pilot-scale study demonstrates that the E-peroxone process can provide a feasible, effective, and energy-efficient alternative for micropollutant abatement and bromate control in water and wastewater treatment.