Bioaerosol Emission from Biofilters: Impact of Bed Material Type and Waste Gas Origin

Abstract

Three semi-technical scale biofilters were applied to treat waste gases at different industrial sites in Poland: a mechanical–biological treatment plant of municipal solid waste, a wastewater treatment plant and a food industry plant. Two types of materials were used as beds in the biofilters: stumpwood chips and pine bark, and stumpwood chips, pine bark and compost from green waste. Both bed materials supported the microbial growth and high numbers (106–108 cfu/g dry mass (DM)) of culturable bacteria, and fungi in beds were observed. There was no correlation between the number of microorganisms (cfu/g DM) and the respiratory activity in the biofilter beds. However, microbial respiration activity corresponded with microbial abundance expressed as microbial equivalents (ME), which was calculated based on adenosine triphosphate (ATP) determination. The biofilters either reduced or increased bioaerosol emissions from industrial plants, depending on the microbial content in the waste gases. A high microbial content in the waste gases made the effect of microbial emission from the biofilter bed negligible. The type of biofilter bed and number of microorganisms in the bed also influenced the final bioaerosol emission, but these factors were relevant for biofilters that treated waste gases with low microbial concentrations.