Treatment of air polluted with high concentrations of toluene and xylene in a pilot-scale biofilter

Abstract

: 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.

Effect of Flow Rate, Concentration and Transient—State Operations on the Performance of a Biofilter Treating Xylene Vapors

“…5. Similar trends in pressure drop values have been reported in the literature for compost biofilters (Deshusses 1997;Jorio et al 1998). A further increase in loading rate (90-185 gm −3 h −1 ) in phase III resulted in a sharp decline of RE to 40-50%.…”

“…This EC value was higher than the values reported in the literature for biofiltration of xylene. EC values ranging between 60 and 70 gm −3 h −1 were reported at a loading rate of 250, 110, and 86 gm −3 h −1 in a specifically conditioned peat bio- Jorio et al (1998), Bibeau et al (2000), and Elmrini et al (2004).…”

Biofiltration of gasoline and diesel aliphatic hydrocarbons

“…The feasibility of simultaneous biodegradation of multiple hydrocarbons may depend on substrate interactions, which could either enhance or suppress the removal of some of the mixture's components at the expense of the others (Schindler and Friedl, 1995;Deshusses, 1997;Jorio et al, 1998;Holubar et al, 1999;Lu et al, 2001;Dupasquier et al, 2002;Kim, 2003;Morales et al, 2003;Gabaldón et al, 2006;Hassan and Sorial, 2010). In addition, hydrophobic/lipophilic hydrocarbons are known to cause changes in the structure and function of cell membranes (Sikkema et al, 1995), which, depending on the abundance of such components, could negatively affect the biofiltration efficiency of the entire mixture.…”

Adsorption and degradation of model volatile organic compounds by a combined titania–montmorillonite–silica photocatalyst

“…Kinds of physical, chemical and biological techniques have been utilized to remove them from air [1][2][3]. Among these different end-of-pipe abatement techniques, activated carbon adsorption is the most widely used.…”