title: Anoxic biodegradation of BTEX in a biotrickling filter.
abstract: Emissions of BTEX (benzene, toluene, ethylbenzene and xylene) from the petrochemical industry are characterized by a low pollutants concentration and the absence of oxygen. Biodegradation of these pollutants using nitrate as the electron acceptor is of key interest to reuse the residual gas for inertization purposes. However, the biological mineralization of BTEX is often limited by their recalcitrant nature and the toxicity of the secondary metabolites produced. The potential of an anoxic biotrickling filter for the treatment of a model O2-free BTEX-laden emission at inlet individual concentrations of ~700mgm-3was here evaluated. A UV oxidation step was also tested both in the recycling liquid and in the inlet gas emission prior to biofiltration. Removal efficiencies >90% were achieved for both toluene and ethylbenzene, corresponding to elimination capacities (ECs) of 1.4±0.2gm-3h-1and 1.5±0.3gm-3h-1, respectively, while ~45% of xylene (EC=0.6±0.1g m-3h-1) was removed at a liquid recycling rate of 2mh-1. Benzene biodegradation was however limited by the accumulation of toxic metabolites in the liquid phase. The oxidation of these intermediates in the recycling liquid by UV photolysis boosted benzene abatement, achieving an average EC of 0.5±0.2gm-3h-1and removals of ~40%. However, the implementation of UV oxidation as a pretreatment step in the inlet gas emission resulted in the deterioration of the BTEX biodegradation capacity of the biotrickling filter. Finally, a high bacterial diversity was observed throughout the entire experiment, the predominant phyla being Proteobacteria and Deinococcus-thermus.
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain; Department of Environmental Engineering, Technical University of Istanbul, 34469 Istanbul, Turkey.
authors.forename: Ilker
authors.initials: I
authors.lastname: Akmirza
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain.
authors.forename: Celia
authors.initials: C
authors.lastname: Pascual
authors.affiliation: Department of Chemical Engineering and Environmental Technology, Technical University Federico Santa Maria, Chile.
authors.forename: Andrea
authors.initials: A
authors.lastname: Carvajal
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain.
authors.forename: Rebeca
authors.initials: R
authors.lastname: Pérez
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain.
authors.forename: Raúl
authors.initials: R
authors.lastname: Muñoz
authors.affiliation: Department of Chemical Engineering and Environmental Technology, University of Valladolid, Dr. Mergelina s/n., Valladolid 47011, Spain. Electronic address: raquel.lebrero@iq.uva.es.
authors.forename: Raquel
authors.initials: R
authors.lastname: Lebrero
mesh_terms: D001554:Benzene / Q000378:metabolism*; D001555:Benzene Derivatives / Q000378:metabolism*; D001673:Biodegradation, Environmental; D020560:Proteobacteria; D014050:Toluene / Q000378:metabolism*; D014992:Xylenes / Q000378:metabolism*
chemical_list: D001555:Benzene Derivatives; D014992:Xylenes; D014050:Toluene; D001554:Benzene; C004912:ethylbenzene
keywords: Anoxic BTEX removal; Benzene; Biotrickling filtration; Ethylbenzene; Toluene; Xylene