The pollution of bioaerosols in hospital sewage purification process: Composition characteristics, seasonal variation and risk assessment

The hospital sewage contains many pathogenic bacteria, which may produce bioaerosol and spread diseases during the sewage treatment process. In this study, the characteristics, seasonal variation, and risk assessment of the bioaerosol in hospital sewage treatment stations (HSTS) were analyzed. The concentration of bacteria in bioaerosol generated from BRT (251 CFU/m3) was higher than that in the air at SG (75 CFU/m3). Summer (506 CFU/m3) and autumn (32 CFU/m3) showed the highest levels of bacterial and intestinal bacterial concentration in the air at BRT, respectively. The percentage of microorganisms attached to small particles (<2.1 μm) (SP) ranged from 22.64% to 66.66%, which was most prevalent in winter (66.66%). Brevundimonas (38.99%), Bacteroides (11.25%), Pseudomonas (49.48%), and Ochrobactrum (41.02%) were the dominant genera in spring, summer, autumn, and winter, respectively. The dominant bacterial genera of bioaerosol in BRT and SG showed obvious seasonal variations, Bacillus were present in each season. The hazard quotient (HQ) of males was higher than that of females (HQmales: 2.60 × 10−3, HQfemales: 2.18 × 10−3), and the inhalation risks of the bacteria were highest in summer (5.98 × 10−2). Temperature and relative humidity positively influenced intestinal bacteria in bioaerosols. The potentially pathogenic were highest in spring. One hour after the sampling point, the result of the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) mode showed that the diffusion area of bioaerosol in winter (182.03 km2) was the largest. This study focused on the bioaerosol produced by hospital sewage. The results effectively revealed the seasonal variation and risk characteristics of bioaerosols, which could serve as a theoretical foundation for the future control and reduction of bioaerosols in the process of purifying municipal water.