Air pollution represents an increasing environmental problem. Among the existing treatment techniques, biofiltration is an environmentally friendly and cost effective alternative. One of the challenges of this technology is to achieve a high steady state removal of hydrophobic compounds. Experiments were carried out with the fungus Scedosporium apiospermum TB1 eliminating toluene. The mold was very efficient for a sustained period of time. The biofilter used was divided into two equal volumes of 4.25 L, each packed with a different type of ceramic rings. The two supports chosen have different water retention abilities (19%, and 64% (w/w)) for void volumes of respectively 0.74 and 0.84. Such materials are recognized for their apropriate hydrodynamic behavior and were used to allow strong hyphal growth and limit pressure drop. The overall empty bed residence time was 1.5 min. Carbon dioxide production and biomass content were regularly monitored and indicate a good biofilm development on the support materials (biomass content higher than 50 mg/g). After optimization of water and nutrient delivery, a global elimination capacity greater than 200 g/m~3/h was reached with a negligeable pressure drop (less than 2 mm of water). Comparison of removal efficiency on the two types of ceramic rings showed that the lower moisture content material allowed the best elimination capacity (290 g/m~3/h). This result indicates, in the case of a fungal biofilter, that materials with a reduced water retention ability can represent an efficient support for removing hydrophobic pollutants while controlling growth.
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