title: Assessing the environmental impact of biobleaching: effects of the operational conditions.
abstract: The environmental impact of enzyme bleaching stages applied to oxygen-delignified eucalypt kraft pulp was assessed via the chemical oxygen demand (COD), color, absorbance spectrum, residual enzyme activity and Microtox toxicity of the effluents from a laccase-HBT (1-hydoxybenzotriazole) treatment. The influence of the laccase and HBT doses, and reaction time, on these effluent properties was also examined. The laccase dose was found to be the individual variable most strongly affecting COD, whereas the oxidized form of HBT was the main source of increased color and toxicity in the effluents. Moreover, it inactivated the enzyme. Oxidation of the mediator was very fast and essentially dependent on the laccase dose. Using the laccase-mediator treatment after a xylanase stage improved pulp properties without affecting effluent properties. This result holds great promise with a view to the industrial implementation of biobleaching sequences involving the two enzymes in the future.
authors.affiliation: Textile and Paper Engineering Department, ETSEIAT, Universitat Politècnica de Catalunya, Colom 11, E-08222 Terrassa, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Valls
authors.forename: Elisabet
authors.initials: E
authors.lastname: Quintana
authors.forename: M Blanca
authors.initials: MB
authors.lastname: Roncero
mesh_terms: D001673:Biodegradation, Environmental; D004396:Coloring Agents / Q000737:chemistry*; D004777:Environment; D004795:Enzyme Stability; D042845:Laccase / Q000737:chemistry*; D010100:Oxygen / Q000737:chemistry; D010209:Paper
chemical_list: D004396:Coloring Agents; D042845:Laccase; D010100:Oxygen