title: Indirect electroreduction as pretreatment to enhance biodegradability of metronidazole.
abstract: The removal of metronidazole, a biorecalcitrant antibiotic, by coupling an electrochemical reduction with a biological treatment was examined. Electroreduction was performed in a home-made flow cell at -1.2V/SCE on graphite felt. After only one pass through the cell, analysis of the electrolyzed solution showed a total degradation of metronidazole. The biodegradability estimated from the BOD5/COD ratio increased from 0.07 to 0.2, namely below the value usually considered as the limit of biodegradability (0.4). In order to improve these results, indirect electrolysis of metronidazole was performed with a titanium complex known to reduce selectively nitro compounds into amine. The catalytic activity of the titanium complex towards electroreduction of metronidazole was shown by cyclic voltammetry analyses. Indirect electrolysis led to an improvement of the biodegradability from 0.07 to 0.42. To confirm the interest of indirect electroreduction to improve the electrochemical pretreatment, biological treatment was then carried out on activated sludge after direct and indirect electrolyses; different parameters were followed during the culture such as pH, TOC and metronidazole concentration. Both electrochemical processes led to a more efficient biodegradation of metronidazole compared with the single biological treatment, leading to an overall mineralization yield for the coupling process of 85%.
authors: Institut des Sciences Chimiques de Rennes, Université de Rennes 1, UMR-CNRS 6226, Campus de Beaulieu, 35042 Rennes Cedex, France; Laboratoire de recherche de Catalyse d'Electrochimie de Nanomatériaux et leurs applications et de didactique CENAD, Institut National des Sciences Appliquées et de Technologie (INSAT), B.P.N°676, 1080 Tunis Cedex, Tunisia; Université Européenne de Bretagne, 35000, France.
authors: I
authors: I
authors: Saidi
authors: Institut des Sciences Chimiques de Rennes, Université de Rennes 1, UMR-CNRS 6226, Campus de Beaulieu, 35042 Rennes Cedex, France; Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, UMR-CNRS 6226, Avenue du Général Leclerc, CS 50837, 35042 Renne Cedex 7, France; Université Européenne de Bretagne, 35000, France.
authors: I
authors: I
authors: Soutrel
authors: Institut des Sciences Chimiques de Rennes, Université de Rennes 1, UMR-CNRS 6226, Campus de Beaulieu, 35042 Rennes Cedex, France; Université Européenne de Bretagne, 35000, France.
authors: D
authors: D
authors: Floner
authors: Institut des Sciences Chimiques de Rennes, Université de Rennes 1, UMR-CNRS 6226, Campus de Beaulieu, 35042 Rennes Cedex, France; Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, UMR-CNRS 6226, Avenue du Général Leclerc, CS 50837, 35042 Renne Cedex 7, France; Université Européenne de Bretagne, 35000, France.
authors: F
authors: F
authors: Fourcade
authors: Laboratoire de recherche de Catalyse d'Electrochimie de Nanomatériaux et leurs applications et de didactique CENAD, Institut National des Sciences Appliquées et de Technologie (INSAT), B.P.N°676, 1080 Tunis Cedex, Tunisia.
authors: N
authors: N
authors: Bellakhal
authors: Institut des Sciences Chimiques de Rennes, Université de Rennes 1, UMR-CNRS 6226, Campus de Beaulieu, 35042 Rennes Cedex, France; Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, UMR-CNRS 6226, Avenue du Général Leclerc, CS 50837, 35042 Renne Cedex 7, France; Université Européenne de Bretagne, 35000, France. Electronic address: Abdeltif.Amrane@univ-rennes1.fr.
authors: A
authors: A
authors: Amrane
authors: Institut des Sciences Chimiques de Rennes, Université de Rennes 1, UMR-CNRS 6226, Campus de Beaulieu, 35042 Rennes Cedex, France; Université Européenne de Bretagne, 35000, France. Electronic address: Florence.Geneste@univ-rennes1.fr.
authors: F
authors: F
authors: Geneste
mesh_terms: D000890:Anti-Infective Agents / Q000737:chemistry* / Q000378:metabolism; D057919:Biological Oxygen Demand Analysis; D002384:Catalysis; D004563:Electrochemistry; D008795:Metronidazole / Q000737:chemistry* / Q000378:metabolism; D009942:Organometallic Compounds / Q000737:chemistry; D010084:Oxidation-Reduction; D012722:Sewage / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000378:metabolism
chemical_list: D000890:Anti-Infective Agents; D009942:Organometallic Compounds; D012722:Sewage; D014874:Water Pollutants, Chemical; C406884:titanocene; D008795:Metronidazole
keywords: Biological treatment; Combined process; Indirect electroreduction; Metronidazole; Titanium complex