Identification of airborne fungi’s concentrations in indoor and outdoor air of municipal wastewater treatment plant

Background: Airborne fungi play an important role the quality of indoor and outdoor air. The aim of this study was to investigate the concentration of airborne fungi around different parts of the wastewater treatment plant (WWTP) in the west of Ahvaz and its relationship with some important meteorological parameters. Methods: This study was conducted on a WWTP in the west of Ahvaz during 4 months in both cold and warm seasons. Samples were collected from 2 and 10m intervals of the grit chamber (GCh), primary sludge dewatering basin (PSDB), and aeration tank (AT), as well as 60 m upstream (US), downstream (DS), and administrative building (AB) of the WWTP. Bioaerosols were collected using passive sampling method. Temperature, humidity, wind speed, wind direction, and ultraviolet index (UV) were also measured at the time of sampling. Results: The total concentration of fungi was 46.1 ± 43 CFU/plate/h. The highest concentration of fungi (92.2 ± 28.12 CFU/plate/h) was found 2 m away from the GCh in the cold season and the lowest one (24.6 ± 6.67 CFU/plate/h) was found at the 10m distance of the AT in the warm season. The dominant fungal genus included Cladosporium, Alternaria, Yeast, and Aspergillus, respectively. Also, there was a significant relationship between the degree of fungal contamination in different units, the US and DS of the WWTP, and there was a negative relationship between the release of fungi and UV. Conclusion: According to the results, grit chamber plays an important role in releasing airborne fungi. Also, airborne fungi were reduced with an increase in distance and UV.