Bioaerosols emission and exposure risk of a wastewater treatment plant with A2O treatment process.

Abstract The characteristics of bioaerosol emissions from wastewater treatment plants (WWTPs) have attracted extensive attention. The anaerobic-anoxic-oxic (A²O) process, which uses the activated sludge approach to wastewater treatment, is the most widely used process in WWTPs. Concentration, size distribution, population, and exposure risk from bacteria and fungi in bioaerosols of WWTPs using the A²O process were studied in this work. The results showed that the maximum concentration of airborne bacteria (1.00 × 10⁴ Colony Forming Units per cubic meter (CFU m⁻³)) and fungi (1.44 ×10⁴ CFU m⁻³) occurred from the facility's aerobic tank, in summer. As one of the main factors affecting bioaerosol exposure risk, particle size distribution was related to season. The study found that particles larger than 3.3 µm in diameter were detected mainly in spring and summer, while particles less than 3.3 µm were detected mainly in autumn and winter, whether bacterial aerosol or fungal aerosol. In addition, pathogenic bacteria were observed in bioaerosols from WWTPs, with 18 of the 65 species of bacteria detected found to be potentially or opportunistically pathogenic, such as Chryseobacterium , Stenotrophomonas , Alcaligenes, Micrococcus, Pantoea, Enterobacter and Escherichia-Shigella. The presence of these pathogens further increased the exposure risk from bioaerosols. The results of an inhalation risk assessment for airborne bacteria and fungi indicated that potential adverse health risks for adults mainly occurred in spring, summer, and autumn. On this basis, it was concluded that WWTP operators should set up effective bioaerosol controls as soon as possible to protect the health of workers, and of residents near the plant. Graphical abstract fx1 Highlights • Microbial concentration, size, population and risk of bioaerosol were detected. • Aerobic tank is main source of bioaerosols in wastewater treatment plant outdoor. • The highest detection concentration of bioaerosol occurred in summer. • Pathogenic bacteria accounted for 28% of the bacteria detected in bioaerosol. • WWTP bioaerosol has a certain inhalation risk for workers and nearby residents. [ABSTRACT FROM AUTHOR]