title: A ferrous oxalate mediated photo-Fenton system: toward an increased biodegradability of indigo dyed wastewaters.
abstract: This study assessed the applicability of a ferrous oxalate mediated photo-Fenton pretreatment for indigo-dyed wastewaters as to produce a biodegradable enough effluent, likely of being derived to conventional biological processes. The photochemical treatment was performed with ferrous oxalate and hydrogen peroxide in a Compound Parabolic Concentrator (CPC) under batch operation conditions. The reaction was studied at natural pH conditions (5-6) with indigo concentrations in the range of 6.67-33.33 mg L(-1), using a fixed oxalate-to-iron mass ratio (C(2)O(4)(2-)/Fe(2+)=35) and assessing the system's biodegradability at low (257 mg L(-1)) and high (1280 mg L(-1)) H(2)O(2) concentrations. In order to seek the optimal conditions for the treatment of indigo dyed wastewaters, an experimental design consisting in a statistical surface response approach was carried out. This analysis revealed that the best removal efficiencies for Total Organic Carbon (TOC) were obtained for low peroxide doses. In general it was observed that after 20 kJ L(-1), almost every treated effluent increased its biodegradability from a BOD(5)/COD value of 0.4. This increase in the biodegradability was confirmed by the presence of short chain carboxylic acids as intermediate products and by the mineralization of organic nitrogen into nitrate. Finally, an overall decrease in the LC(50) for Artemia salina indicated a successful detoxification of the effluent.
authors.affiliation: Department of Chemical Engineering & Chemistry, Universidad Iberoamericana, Cd. de Mexico, Prolongación Paseo de la Reforma 880, Col. Lomas de Santa Fe, 01219 Mexico, D.F., Mexico.
authors.forename: Michel
authors.initials: M
authors.lastname: Vedrenne
authors.forename: Ruben
authors.initials: R
authors.lastname: Vasquez-Medrano
authors.forename: Dorian
authors.initials: D
authors.lastname: Prato-Garcia
authors.forename: Bernardo A
authors.initials: BA
authors.lastname: Frontana-Uribe
authors.forename: Margarita
authors.initials: M
authors.lastname: Hernandez-Esparza
authors.forename: Juan Manuel
authors.initials: JM
authors.lastname: de Andrés
mesh_terms: D000818:Animals; D001156:Artemia; D001673:Biodegradation, Environmental; D057919:Biological Oxygen Demand Analysis; D002244:Carbon / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D004396:Coloring Agents / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D007928:Lethal Dose 50; D008800:Mexico; D009566:Nitrates / Q000737:chemistry; D019815:Oxalic Acid / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013783:Textile Industry; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000633:toxicity
chemical_list: D002244:Carbon; D004396:Coloring Agents; D006861:Hydrogen Peroxide; D007501:Iron; D009566:Nitrates; D019815:Oxalic Acid; D062065:Wastewater; D014874:Water Pollutants, Chemical; C045076:Fenton's reagent