Abstract
Biofiltration is a common technology for treating volatile organic compounds (VOCs); however, bioaerosols may be emitted in the gas flow, indicating a potential risk to human health. In this study, we analyzed the emission characteristics of bioaerosol and suspended particles (mainly nonbiological particles) emitted from biofilters and their health risk at different gas velocities and temperatures and with different amounts of moisture in the packing bed. Results showed that a high gas velocity enabled easy transport of microbes from the carriers. The maximum bacterial aerosol outlet concentration was 223 CFU m−3 at 50°C, although the fungal aerosol concentration decreased at temperatures above 25°C. The peak bacterial concentration was 349 CFU m−3, with a moisture content of 70%, whereas the highest fungi concentration was nearly 267 CFU m−3, with a moisture content of 40%. The bioaerosol concentrations also changed with the experimental conditions: A high gas velocity, low temperature, and high moisture content favored the emission of fine particles; however, changes in the concentration and size distribution of coarse particles were not obvious. The relationship between bioaerosols and suspended particle emissions demonstrates that biofilters are a source of bioaerosol emissions despite the removal of nonbiological suspended particles due to filtration. The health risk evaluation indicates that bioaerosol emissions from biofilters pose the highest risk of infection via inhalation to adult males.
Highlights
Bioaerosols are the suspension of airborne particles that are living and those originating from living organisms, including pollen, fungal spores, bacteria, viruses, animal dander, and mite-associated fragments (ACGIH, 1999; Chow et al, 2015; Tarigan et al, 2017)
The maximum bacterial aerosol outlet concentration was 223 CFU m−3 at 50°C, the fungal aerosol concentration decreased at temperatures above 25°C
The bioaerosol concentrations changed with the experimental conditions: A high gas velocity, low temperature, and high moisture content favored the emission of fine particles; changes in the concentration and size distribution of coarse particles were not obvious
Summary
Bioaerosols are the suspension of airborne particles that are living and those originating from living organisms, including pollen, fungal spores, bacteria, viruses, animal dander, and mite-associated fragments (ACGIH, 1999; Chow et al, 2015; Tarigan et al, 2017). These particles are very small and range in size from less than 1 μm to 100 μm (Yu, 2002). Wang et al (2009) examined the bioaerosol emissions from the biofilter using ultraviolet photodegradation as pretreatment They found that the ozone produced by ultraviolet photodegradation decreased the concentration of bioaerosol from 1.38 × 103 CFU m−3 (without pretreatment) to 60 CFU m−3
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