Fungal Biofiltration of Toluene on Ceramic Rings

Fungal biofilters attain higher toluene elimination rates compared to bacterial systems. However, strong mycelia growth can cause clogging. In the present work, toluene biofiltration with the fungus Paecilomyces variotii CBS 115145 was tested with two rigid packing materials that allow high mycelia growth. The reactor had two 4.25 L sections, each packed with ceramic Raschig rings differing in water retention capacity and internal porosity. After optimizing nutrient solution delivery, an overall maximum elimination capacity of 245 g∕ m3 ∕h was obtained. Higher elimination capacity (290 g∕ m3 ∕h) was measured in the ceramic ring with lower water content, indicating the interest of such packing material for treating hydrophobic pollutants in fungal biofilters. Additional experiments with this support in a 2 L biofilter showed bacterial contamination, but the fungal activity was responsible for about 70% of the total removal. The support with less humidity showed greater aerial growth, which possibly improves removal efficiency by favoring the direct transfer of pollutants from the gas phase to the microorganism.