Biofilters based on the action of fungi

Traditional biofilters for waste gas treatment are mainly based on the degr adation activity of CD bacteria. The application of fungi in biofilters has several advantages: fungi are more resistant to acidification and drying o ut, and the aerial mycelia of fungi forma larger surface area in the gas ph ase than bacterial biofilms, which may facilitate the uptake of hydrophobic volatile compounds. The research described here identifies important condi tions for the operation of fungal-based biofilters. Biofilters with perlite packing were operated at different pHs and relative inlet gas humidities. Toluene was used as a model pollutant. It was shown that a low pH is a prer equisite for fungal growth in biofilters. Also, the fungal biofilters were more resistant to drying out and more active than the bacterial biofilters. Fungal biofilters eliminated 80-125 g toluene/m(3) filterbed/h. Several me asures that could limit the clogging of fungal biofilters with fungal bioma ss were investigated. The introduction of mites helped to control excessive fungal growth and pressure drop. The pressure drop of a perlite/fungi/mite s filter of 1 m height, loaded with 200 m(3) gas/m(3) filter/h stabilised a round 130 Pa. Biofilters based on the action of fungi are cost-effective fo r the treatment of waste gases containing aromatic compounds, alkenes and o ther hydrophobic compounds.