title: Coupling of acrylic dyeing wastewater treatment by heterogeneous Fenton oxidation in a continuous stirred tank reactor with biological degradation in a sequential batch reactor.
abstract: This work deals with the treatment of a recalcitrant effluent, from the dyeing stage of acrylic fibres, by combination of the heterogeneous Fenton's process in a continuous stirred tank reactor (CSTR) with biological degradation in a sequential batch reactor (SBR). Three different catalysts (a commercial Fe/ZSM-5 zeolite and two distinct Fe-containing activated carbons - ACs - prepared by wet impregnation of iron acetate and iron nitrate) were employed on the Fenton's process, and afterwards a parametric study was carried out to determine the effect of the main operating conditions, namely the hydrogen peroxide feed concentration, temperature and contact time. Under the best operating conditions found, using the activated carbon impregnated with iron nitrate, 62.7% of discolouration and 39.9% of total organic carbon (TOC) reduction were achieved, at steady-state. Furthermore, a considerable increase in the effluent's biodegradability was attained (BOD5:COD ratio increased from <0.001 to 0.27 and SOUR - specific oxygen uptake rate - from <0.2 to 11.1 mg O2/(gVSS·h)), alongside a major decrease in its toxicity (from 92.1 to 94.0% of Vibrio fischeri inhibition down to 6.9-9.9%). This allowed the application of the subsequent biological degradation stage. The combination of the two processes provided a treated effluent that clearly complies with the legislated discharge limits. It was also found that the iron leaching from the three catalysts tested was very small in all runs, a crucial factor for the stability and long-term use of such materials.
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: Bruno M
authors.initials: BM
authors.lastname: Esteves
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: CS
authors.lastname: Rodrigues
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: RA
authors.lastname: Boaventura
authors.affiliation: Department of Inorganic Chemistry, Faculty of Sciences, University of Granada, Avenida de Fuente Nueva, 18071 Granada, Spain.
authors.forename: F J
authors.initials: FJ
authors.lastname: Maldonado-Hódar
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: Luís M
authors.initials: LM
authors.lastname: Madeira
mesh_terms: D001673:Biodegradation, Environmental; D019149:Bioreactors; D004396:Coloring Agents / Q000737:chemistry / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron; D010084:Oxidation-Reduction; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism*; D017641:Zeolites / Q000737:chemistry
chemical_list: D004396:Coloring Agents; D006861:Hydrogen Peroxide; D007501:Iron; D062065:Wastewater; D014874:Water Pollutants, Chemical; D017641:Zeolites; C570564:ZSM-5 zeolite
keywords: Biological degradation; Continuous stirred tank reactor; Heterogeneous Fenton oxidation; Textile dyeing wastewater