Bioaerosol emission characteristics from an underground wastewater treatment plant: Distribution, microbial population, influencing factors and health risk assessment

Abstract

With the global spread of airborne pathogens, bioaerosols carrying pathogens have received widespread attention. Wastewater treatment plants accumulate large amounts of bioaerosols, posing a significant threat to the surrounding environment and public health. In this study, the distribution, microbial population, influencing factors and health risk of bioaerosols from an underground wastewater treatment plant (UWWTP) were investigated. The results showed that the total bioaerosol concentrations of UWWTP were 639–6968 CFU/m³, with the main contributions being pretreatment and sludge treatment. Moreover, with the deepening of the wastewater treatment process, the concentrations of bioaerosols gradually decreased. The proportion of respirable fraction of UWWTP bioaerosols was 52.89 %–80.63 %. Environmental factors significantly affected the concentration and particle size distribution of bioaerosols. Rhodococcus was the dominant bacterium in the UWWTP bioaerosols. Notably, some pathogenic bacteria such as Pseudomonas, Ahniella, and Macellibacteroides were detected in bioaerosols, some of which originated from wastewater or sludge. In addition, inhalation of bioaerosols is the main way to threaten human health, and bioaerosols emitted by UWWTP in May can pose a non-carcinogenic risk to humans (HI>1). Therefore, the long-term contamination characteristics of bioaerosols in underground wastewater treatment plants should be fully investigated and effective preventive measures should be established.