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Enoxacin degradation by photo-Fenton process combined with a biological treatment: optimization and improvement of by-products biodegradability
- Annabi, C., Abou Dalle, A., Fourcade, F., Assadi, A. A., Soutrel, I., Bellakhal, N., Amrane, A.
- International journal of environmental science and technology 2019 v.16 no.2 pp. 655-666
- antibiotics, biochemical oxygen demand, biodegradability, biodegradation, biological treatment, byproducts, chemical oxygen demand, fluoroquinolones, hydrogen peroxide, iron, irradiation, light intensity, mineralization, monitoring, oxidation, photolysis, sludge, ultraviolet radiation
- This study evaluates the effectiveness of coupling a photo-Fenton process with a biological treatment on the mineralization of enoxacin, an antibacterial agent belonging to the fluoroquinolones group. The influence of some operating parameters, such as UV light intensity, hydrogen peroxide and Fe(II) concentrations, on 50 mg L⁻¹ enoxacin degradation and by-products mineralization was evaluated. The biodegradability of the target molecule was also investigated, reporting a BOD₅ on COD ratio of 0.95 after 60 min of irradiation at 15 mmol L⁻¹ of H₂O₂, 0.5 mmol L⁻¹ of Fe(II) and 30 W m⁻² of UV A light intensity. The monitoring of the advanced oxidation state (AOS) of the irradiated solution during the treatment displayed a maximal oxidation state of 0.25 for 90 min of photo-degradation. A comparison between the photo-Fenton process and other oxidative processes [UV alone, UV/H₂O₂, H₂O₂, H₂O₂/Fe(II)] was carried out showing a marked improvement in enoxacin mineralization while combining UV A light with the Fenton reagent (41% of TOC decay improvement compared to the Fenton process). Finally, activated sludge culture for non-treated and pre-treated enoxacin at optimal conditions was conducted during 10 days. The obtained TOC results reported a mineralization improvement with a maximal mineralization yield of 43% for the biodegradation of irradiated samples. The relevance of coupling the photo-Fenton process with a biological process for the enoxacin treatment was therefore proven.