Treatment of VOCs in biofilters inoculated with fungi and microbial consortium.

An experimental study on the removal of xylene vapours from an air stream was conducted on three identical upflow laboratory-scale wood-chips-based bed biofilters. Three different inoculums were used: fungi (Phanerochaete chrysosporium and Cladosporium sphaerospermum), a bacterial consortium (EVB110), and a mixed culture of fungi and EVB 110. The empty bed gas residence time was 59 s, and various inlet concentrations of the contaminant were tested. The results obtained revealed a strong correlation between the average temperature of the biofilter and the intensity of the microbial activity in the filter bed. In addition, the mass of carbon dioxide produced per mass of xylene removed was equal to 3.03, indicating elimination of the pollutant by aerobic biodegradation. The removal rates of xylene in both fungal and bacterial systems were similar up to an inlet load of 100 g m(-3) h(-1). However, a better performance was achieved in the fungal system at higher inlet loads of the pollutant. The maximum elimination capacity achieved in the fungal and bacterial systems was 77 and 58 g m(-3) h(-1), respectively; and an early set-off of the inhibition effects was observed in the latter. The bioreactor inoculated with the mixed culture was the least effective, with a maximum elimination capacity of only 38 g m(-3) h(-1). Problems with microbial population survival and competition among different types of microorganisms could be responsible of this lower performance. The fungal system was also tested for the removal of toluene vapour and achieved a maximum elimination capacity of 110 g m(-3) h(-1).