Introduction: Bioaerosols emitted from wastewater treatment plants can significantly impact human health. This study aimed to evaluate the concentrations of airborne bacteria and fungi and assess their associated risks at the WWTPs of Imam Sajjad Hospital in Yasuj.
Methods: Air samples were collected using an airborne microbial sampler (QuickTake 30) at a flow rate of 28.3 L/min for 5 minutes. The sampling locations included five sites within the WWTPs, two sites located 100 m and 500 m downstream, and a background sampling site. A total of 240 samples were collected. A risk assessment for airborne bacteria and fungi was conducted using the United States Environmental Protection Agency model. Bacterial genera were identified through the examination of Gram-stained smears, morphological analysis, and biochemical tests. Fungal colonies were identified based on colony characteristics and spore morphology assessment, and the data were analyzed using SPSS software version 20.
Results: The aeration tank exhibited the highest airborne bacterial concentration (2001.25 ± 2139.36 CFU/m³), while the grit chamber recorded the lowest concentration (592.57 ± 351.13 CFU/m³). For fungi, the grit chamber had the highest load (482.14 ± 296.98 CFU/m³), whereas the chlorination unit had the lowest concentration at (223.12 ± 133.70 CFU/ m³). Staphylococcus and Bacillus were identified as the predominant bacterial genera in the WWTPs, while Rhizopus and Cladosporium were the dominant fungal genera in the WWTPs. The hazard quotient for airborne bacteria and fungi was less than 1, indicating an acceptable level of risk for exposure.
Conclusion: To minimize bioaerosol production from aeration tanks, the design of aeration equipment should be optimized.