Metronidazole removal by means of a combined system coupling an electro-Fenton process and a conventional biological treatment By-products monitoring and performance enhancement

Arwa Abou Dalle (1) , Hayet Djelal (2) , Florence Fourcade (1) , Lionel Domergue (1) , Aymen Amin Assadi (1) , Thomas Lendormi (3) , Samir Taha (4) , Abdeltif Amrane (1)

1 ISCR - Institut des Sciences Chimiques de Rennes
2 UniLaSalle Rennes - Ecole des Métiers de l'Environnement
3 IRDL - Institut de Recherche Dupuy de Lôme
4 LU / ULB - الجامعة اللبنانية [بيروت] = Lebanese University [Beirut] = Université libanaise [Beyrouth]

In order to mineralize Metronidazole (MTZ), a process coupling an electro-Fenton pretreatment and a biological degradation was implemented. A mono-compartment batch reactor containing a carbon-felt cathode and a platinum anode was employed to carry out the electro-Fenton pretreatment of MTZ. A total degradation of MTZ (100 mg L) was observed at 0.07 mA.cm after only 20 min of electrolysis. Yet, after 1 and 2 h of electrolysis, the mineralization level remained low (16.2% and 32% respectively), guaranteeing a significant residual organic content for further biological treatment. LCMS/MS was used to determine the intermediates by-products and hence to propose a plausible degradation pathway. An increase from 0 to 0.44 and 0.6 for 1 and 2 h of electrolysis was observed for the BOD/COD ratio. Thus, from 1 h of electro-Fenton pretreatment, the electrolysis by-products were considered biodegradable. A biological treatment of the electrolysis by-products after 1 and 2 h was then realized. The mineralization yields reached very close values, about 84% for 1 and 2 h of electrolysis after 504 h of biological treatment, namely close to 89% for the overall process, showing the pertinence of the proposed coupled process.

Mots clés: By-products monitoring; Biological treatment; Metronidazole; Electro-Fenton process; Activated sludge

Domaines: Autre; Ingénierie de l'environnement

Arwa Abou Dalle, Hayet Djelal, Florence Fourcade, Lionel Domergue, Aymen Amin Assadi, et al.. Metronidazole removal by means of a combined system coupling an electro-Fenton process and a conventional biological treatment By-products monitoring and performance enhancement. Journal of Hazardous Materials, 2018, 359, pp.85-95. ⟨10.1016/j.jhazmat.2018.07.006⟩. ⟨hal-01862499⟩