Main content area

Characterization of bioaerosol emissions from two biofilters during treatment of toluene vapours using epifluorescence microscopy

Esquivel-Gonzalez, Saúl, Aizpuru, Aitor, Patrón-Soberano, Araceli, Arriaga, Sonia
International biodeterioration & biodegradation 2017 v.123 pp. 78-86
Gram-negative bacteria, acidification, packaging materials, leachates, biofilters, toluene, air, fluorescent dyes, vapors, emissions, air flow, biomass, fluorescence microscopy, perlite, Gram-positive bacteria, bioaerosols, fungi
Emission of bioaerosols from biofilters during the treatment of toluene vapours was studied. A non-culture-dependent technique, known as epifluorescence microscopy (EM), with several fluorochromes was used to characterize and quantify bioaerosols. The bioaerosol emitted concentrations were between 6.4 × 10⁵ and 1.3 × 10⁸ cells m⁻³air compared with the bioaerosol concentration in ambient air, which was 3.0 × 10⁷±7 × 10⁶ cells m⁻³air. EM allowed for a better estimation of bioaerosol concentrations than culture-dependent techniques. Bioaerosol emission was dependent on the packing material. Perlite was a better packing material in terms of removal efficiency (RE; RE of 60%), with a lower bioaerosol emission (7 × 10⁷ cells m⁻³air) than Tezontle (RE = 40%; 1.3 × 10⁸ cells m⁻³air). The main drawback of perlite was acidification of the bed. Bioaerosols in biofilters A and B were composed of Gram-negative bacteria (45% and 40%, respectively), a similar percentage of Gram-positive bacteria (28%) and fungi (27% and 32%, respectively). After the shutdown periods, Gram-positive bacteria were predominant (∼60%). The biomass concentrations in leachates were twice those in the air flow and were mainly composed of fungi. Overall, the EM technique is a valuable tool to characterize and quantify bioaerosols in biofilters without under evaluation. This is the first estimation of bioaerosol emissions by biofilters inoculated with a microbial consortium using a noncultivable technique.