Removal of Organic Micropollutants from Treated Municipal Wastewater by O₃/UV/H₂O₂ in a UVA-LED Reactor

ABSTRACT

Organic micropollutants (OMPs) have been widely detected in the aqueous environment and their effect on the environment and human health has been studied. The removal of OMPs from effluents of a conventional urban wastewater treatment plant by ozonation as well as photo-enhancement of ozonation using UVA-LED panels and photolysis in the presence and absence of hydrogen peroxide was investigated. In a novel semi-technical reactor municipal wastewater was treated for 2 hours, using ozone – O₃ (3 mg O₃·L⁻¹) and in combination with UVA-LED – O₃/UV (peak wavelength 371 nm, 0.78 W·m⁻2) and in combination with UVA-LED and hydrogen peroxide – O₃/UV/H₂O₂ (20 mg H₂O₂·L⁻¹). The highest removal fractions for all OMPs were obtained with O₃/UV/H₂O₂ (candesartan: 93.3%, irbesartan: 79.9%, 1 H-benzotriazole: 42.2%, hydrochlorothiazide: 40.8%, 4-/5-methyl-1 H-benzotriazole: 39%, and metoprolol: 24%) and with O₃ (diclofenac: 87.2%, carbamazepine: 76.4%, and sulfamethoxazole: 53.5%). As a conclusion of the different AOP combinations of this study, UV photo-enhancement of ozonation has much more beneficial effects on OMP removal when it is combined with an additional H₂O₂ dosing.

KEYWORDS:

• Ozone
• hydrogen peroxide
• photooxidation
• advanced oxidation processes
• organic micropollutants
• wastewater treatment

Acknowledgments

The authors thank Michael Braun, for the HPLC analysis, Dr. Bertram Kuch, for helpful discussions, and Ali Hangi for technical assistance. The authors also thank for financial support from Coordination for the Improvement of Higher Education Personnel – Brazil (CAPES fellow – PDSE process n° 88881.188687/2018-01).