Bioaerosolization behaviour of potential pathogenic microorganisms from wastewater treatment plants: Occurrence profile, social function and health risks

Wastewater treatment plants (WWTPs) are the leading sources of potential pathogenic bioaerosol that cause nonnegligible health risks. However, bioaerosolization behaviour of potential pathogenic microorganisms (PPMs) migrating from wastewater to the atmosphere is still unclear. This study investigated the occurrence profile of PPMs in wastewater, sludge and bioaerosol, then analyzed bioaerosolization level, impact factors and social function. Staphylococcus aureus was selected as the target due to its pathogenicity, and the health risks of workers, engineers and researchers wearing various masks (N90, N95 and medical masks) were evaluated. The results showed that there were 38 and 64 PPMs in bioaerosol from plant A and B. Streptomyces in plant A (average bioaerosolization index, BI= 237.71) and Acinetobacter in plant B (average BI = 505.88) were more likely to migrate from wastewater to the atmosphere forming bioaerosol. Environmental factors (relative humidity, wind speed and temperature) affected both BI and microbial species of PPMs in different ways. PPMs related to fermentation, aerobic chemoheterotrophy, and chemoheterotrophy are the most abundant. Meanwhile microbial networks from plants A and B showed that PPMs were well-connected. Emission level of Staphylococcus aureus bioaerosol can reach 980 +/- 309.19 CFU/m 3 in plant A and 715.55 +/- 44.17 CFU/m 3 in plant B. For three exposure population, disease burden (DB) and annual probability infection (Py) of Staphylococcus aureus bio- aerosol in two plants were both higher than the U.S.EPA benchmark (10 -4 DALYs pppy). All three masks (N90, N95 and medical masks) can decrease Py and DB by at least one order of magnitude. This study illustrated the bioaerosolization behaviour of PPMs comprehensively, which provides a scientific basis for exposure risk pre- vention and control.