Enoxacin degradation by photo-Fenton process combined with a biological treatment: optimization and improvement of by-products biodegradability
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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.
KeywordsEnoxacin degradation Photo-Fenton process Biodegradability improvement Coupling process Activated sludge culture
This work was supported by the Tunisian Ministry of Higher Education and Scientific Research through training fellowships for Miss C. Annabi during her PhD thesis. The authors wish to thank it.
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