: Air bioÐltration is now under active consideration for the removal of the volatile organic compounds from air polluted streams. In order to investigate the performance of this newly developed technology, a bioÐltration pilot unit was operated for a continuous period of 8 months. The bioÐlter column was packed with commercially conditioned peat. At start-up, the Ðlter bed was inoculated with four species of microorganisms. The resulting bioÐlter was fed with air contaminated with toluene, xylene or a mixture of toluene and xylene. The maximum elimination capacities attained were 165 g m~3 h~1 for toluene, 66 g m~3 h~1 for xylene and 115 g m~3 h~1 for the mixture of toluene and xylene. These speciÐc performances exceed the values published in the technical and commercial literature for similar processes. Xylene isomers were degraded in decreasing order of reactivity, m-xylene, p-xylene, o-xylene. In the case of air polluted with a toluene and xylene mixture, it was noticed that the metabolism of toluene biodegradation was inhibited by the presence of xylene. Characterization of the bioÐlm microbial populations after several weeks of operation showed that the dominant strains among the isolated culturable strains from the bioÐlm, even if di †erent from the initially inoculated strains, had at least one physiological property favoring degradation of aromatic organic rings. The performance of the bioÐlter was found to be dependent on the temperature of the Ðlter media and the pressure drop through the bed. Finally, a steady state mathematical model was tested in order to theoretically describe the experimental results. This model is used to illustrate the operating di †usion and reaction regimes at steady state for the case of each pollutant.

Experiments during a period of 93 days are reported on the treatment of waste air containing toluene vapor using a laboratory scale biofilter system packed with peat inoculated with specific florae (Pseudomonas type) and intermittently humidified with a nutrient solution necessary for the survival of the micro-organisms. Design and operation parameters were regularly measured in order to check the performance of the biodegradation process.Under

A laboratory scale biofilter system was used to eliminate toluene and ethanol, the main solvents employed in lacquering, from waste air. A specific micro-flora (mixture of Bacillus for ethanol and two pseudomonas species for toluene) able to degrade ethanol and toluene, was jimed on a packed bed of particles of commercial peat intermittently humidified by a nutrient solution necessary for the suroival of the micro-organisms.In the experiments, polluted gas was fed upwara3 through the bed and pbysical parameten: moisture content ofpat; humidity of aic temperature; pressure drop; inlevoutlet concentration of gas and microbialpopulation were measured regularly in order to check the performance of the biodegradation process.These experiments showed good pe~ormance and good stability of the biofilter over time.

In this study, we describe the removal of toluene vapors in a pilot scale biofilter. Biofiltration tests have been performed in a column fed upward with contaminated air at ambient conditions. The column was packed with a mixture of conditioned biomass and structuring agent on which a mixed microbial population of four selected strains was immobilized and then formed a biolayer. The biofilter was operated under various inlet-airstream toluene concentrations and flow rates of the contaminated airstream. Based on the present measurements, the biofilter proved effective in removing toluene at rates up to 165 g·h-1·m-3 of packing. The effect of some design and operation parameters (concentration of nutrients solution, presence of xylene, gas flow rate, pressure drop, temperature, etc.) are reported.

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