title: Integration of photocatalysis and biological treatment for azo dye removal--application to AR183.
abstract: The feasibility of coupling photocatalysis with biological treatment to treat effluents containing azo dyes was examined in this work. With this aim, the degradation of Acid Red 183 was investigated. The very low biodegradability of AR183 was confirmed beforehand by measuring the biological oxygen demand (BOD5). Photocatalysis experiments were carried out in a closed-loop step photoreactor. The reactor walls were covered by TiO2 catalyst coated on non-woven paper, and the effluent flowed over the photocatalyst as a thin falling film. The removal of the dye was 82.7% after 4 h, and a quasi-complete decolorization (98.5%) was obtained for 10 h of irradiation (initial concentration 100 mg L(-1)). The decrease in concentration followed pseudo-first-order kinetics, with a constant k of 0.47 h(-1). Mineralization and oxidation yields were 80% and 75%, respectively, after 10 h of pretreatment. Therefore, even if target compound oxidation occurs (COD removal), indicating a modification to the chemical structure, the concomitant high mineralization was not in favour of subsequent microbial growth. The BOD5 measurement confirmed the non-biodegradability of the irradiated solution, which remained toxic since the EC50 decreased from 35 to 3 mg L(-1). The proposed integrated process appeared, therefore, to be not relevant for the treatment of AR183. However, this result should be confirmed for other azo dyes.
authors.affiliation: Département de Génie des Procédés, Faculté des Sciences de l'Ingénieur, Université Ferhat Abbas, 19000 Sétif, Algeria.
authors.forename: Derradji
authors.initials: D
authors.lastname: Chebli
authors.forename: Florence
authors.initials: F
authors.lastname: Fourcade
authors.forename: Stephan
authors.initials: S
authors.lastname: Brosillon
authors.forename: Saci
authors.initials: S
authors.lastname: Nacef
authors.forename: Abdeltif
authors.initials: A
authors.lastname: Amrane
mesh_terms: D001391:Azo Compounds / Q000737:chemistry* / Q000633:toxicity; D057919:Biological Oxygen Demand Analysis; D002384:Catalysis; D002712:Chlorides / Q000032:analysis; D004396:Coloring Agents / Q000737:chemistry* / Q000633:toxicity; D009566:Nitrates / Q000032:analysis; D010777:Photochemistry / Q000379:methods*; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D013056:Spectrophotometry, Ultraviolet; D013431:Sulfates / Q000032:analysis; D014025:Titanium / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000633:toxicity
chemical_list: D001391:Azo Compounds; D002712:Chlorides; D004396:Coloring Agents; D009566:Nitrates; D000644:Quaternary Ammonium Compounds; D013431:Sulfates; D014874:Water Pollutants, Chemical; C009495:titanium dioxide; D014025:Titanium