title: Colour removal of dyes from synthetic and real textile wastewaters in one- and two-stage anaerobic systems.
abstract: Decolourisation of the azo dye model compound, Congo Red (CR), and real textile wastewater, was assessed in one- and two-stage anaerobic treatment systems (R₁ and R₂, respectively). High colour removals were achieved in both treatment systems even when a very high CR concentration (1.2 mM) was applied. However, R₂ presented a slightly better stability, in which the acidogenic reactor (R(2,A)) played a major role on dye reduction, as compared to the methanogenic reactor (R(2,M)), evidencing the role of fermentative microorganisms. The minimum electron donor concentration required to sustain dye reduction was much higher than the stoichiometric amount. Additionally, a decrease on the hydraulic retention time (from 24 to 12 h) did not significantly affect decolourisation, indicating that electron transfer was not a concern. Finally, experiments with real textile wastewater showed low decolourisation efficiencies in both systems, most likely due to the presence of dyes not susceptible to reductive decolourisation under these experimental conditions.
authors.affiliation: Department of Hydraulic and Environmental Engineering, Federal University of Ceará, Campus do Pici, Bloco 713. Pici. CEP 60451 970 Fortaleza, Ceará, Brazil.
authors.forename: Paulo Igor M
authors.initials: PI
authors.lastname: Firmino
authors.forename: Marcos Erick R
authors.initials: ME
authors.lastname: da Silva
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Cervantes
authors.forename: André B
authors.initials: AB
authors.lastname: dos Santos
mesh_terms: D000693:Anaerobiosis; D057919:Biological Oxygen Demand Analysis; D003116:Color; D004396:Coloring Agents / Q000302:isolation & purification*; D013783:Textile Industry; D062065:Wastewater / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D062065:Wastewater