title: Treatment of sugarcane vinasse by combination of coagulation/flocculation and Fenton's oxidation.
abstract: The efficiency of individual and integrated processes applied to organic matter reduction and biodegradability improvement of a biodigested sugarcane vinasse wastewater was assessed. Strategies considered were Fenton's oxidation (Strategy 1), coagulation/flocculation (Strategy 2) and the combination of both processes (coagulation/flocculation followed by Fenton's reaction) - Strategy 3. It was found that Fenton's oxidation per se allowed reducing the organic matter, increasing the wastewater biodegradability and a non-toxic effluent was generated; however the cost of treatment was very high (86.6 R$/m(3) - 21.2 €/m(3)). Under optimized conditions, coagulation/flocculation provided a slight increase in effluent's biodegradability, toxicity towards Vibrio fischeri was also eliminated and moderate removals of total organic carbon - TOC - (30.5%), biological oxygen demand - BOD5 - (27.9%) and chemical oxygen demand - COD - (43.6%) were achieved; however, the operating costs are much smaller. The use of dissolved iron resulting from coagulation/flocculation (270 mg/L) as catalyst in the second stage - Fenton's oxidation - was shown to be an innovative and economically attractive strategy. Under optimal conditions overall removals of 51.6% for TOC, 45.7% for BOD5 and 69.2% for COD were achieved, and a biodegradable (BOD5:COD ratio = 0.54) and non-toxic effluent was obtained. In order to increase the efficiency of the process but using less hydrogen peroxide, the Fenton's oxidation was performed by gradually adding the oxidant. This procedure allowed to obtain the highest organic matter removal efficiency (as compared with the addition of all hydrogen peroxide at the beginning of the reaction). This way it was possible to minimize the reagent consumption and, consequently, reduce the treatment cost.
authors.affiliation: LEPABE - Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, R. Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Lígia F
authors.initials: LF
authors.lastname: Guerreiro
authors.affiliation: LEPABE - Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, R. Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Carmen S D
authors.initials: CSD
authors.lastname: Rodrigues
authors.affiliation: Faculdade de Tecnologia de Jaboticabal, "Nilo Stéfani", Av. Eduardo Zambianchi, 31, 14883-130, Vila Industrial, Jaboticabal, SP, Brazil.
authors.forename: Rose M
authors.initials: RM
authors.lastname: Duda
authors.affiliation: Laboratório de Saneamento Ambiental, Departamento de Engenharia Rural, Faculdade de Ciências Agrárias e Veterinárias, UNESP, Universidade Estadual Paulista, Av. Prof. Paulo Donato Castallene, km 5, 14884-900 Jaboticabal, SP, Brazil.
authors.forename: Roberto A
authors.initials: RA
authors.lastname: de Oliveira
authors.affiliation: LSRE - Laboratório de Processos de Separação e Reação, Laboratório Associado LSRE/LCM, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, R. Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Rui A R
authors.initials: RAR
authors.lastname: Boaventura
authors.affiliation: LEPABE - Laboratório de Engenharia de Processos, Ambiente, Biotecnologia e Energia, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, R. Dr. Roberto Frias, 4200-465 Porto, Portugal. Electronic address: mmadeira@fe.up.pt.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Madeira
mesh_terms: D001673:Biodegradation, Environmental; D057919:Biological Oxygen Demand Analysis; D005427:Flocculation; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007501:Iron / Q000737:chemistry; D010084:Oxidation-Reduction; D031786:Saccharum / Q000737:chemistry*; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry
chemical_list: D006861:Hydrogen Peroxide; D007220:Industrial Waste; D007501:Iron; D062065:Wastewater; C045076:Fenton's reagent
keywords: Anaerobic effluent biodegradability; Coagulation/flocculation; Economic analysis; Fenton’s reaction; Sugarcane vinasse; Toxicity