Photocatalytic inactivation of airborne microorganisms in continuous flow using perlite-supported ZnO and TiO2

Abstract

Biological processes for waste treatment are the main source of bioaerosol emissions in urban environments; these air pollutants have detrimental effects on human health, and therefore the development of treatment processes for this kind of pollutants is of high priority. The present work focused on the implementation of photocatalytic systems based on Perlite-supported ZnO and TiO2 to inactivate fungal/bacterial emissions from a biofilter treating ethyl acetate vapors in a steady state process. The results showed that the outlet of the biofilter had a bioaerosol concentration between 1.0 × 106 Cells m−3air and 460.0 × 106 Cells m−3air. Flow cytometer characterization coupled with a viability kit indicated that bioaerosol emission was composed mainly of bacteria (>80%). The photocatalytic system based on ZnO/Perlite achieved the highest percentage of bioaerosol inactivation (70%), with a catalyst activity duration of 7.5 h, while the TiO2/Perlite system showed an inactivation percentage of 40% with a maximum time of photocatalytic activity of 2.0 h. The main mechanism of bioaerosol inactivation was associated with cell death and not with cell damage.