Assessment of Seasonal Variation of Microbial Aerosol and Gaseous Emissions from Wastewater Treatment Plant of Morche Khort Industrial Town

Introduction: Wastewater contains a large number of pathogenic and non-pathogenic microorganisms that can become bioaerosols during the treatment processes in different units of the treatment plant, and pose a risk to workers and nearby residents. In this study, the release of bioaerosols from a wastewater treatment plant of Morche Khort Industrial Town was investigated. 
Materials and Methods: Sampling was actively performed according to EPA standard, in two seasons of spring and summer in 2018-2019, by an environmental sampling pump with a flow rate of 15 l/min and a single-stage impactor. The data were analyzed by SPSS software version 2020. 
Results: The study results showed that the mean number of bacteria in the aeration tank was significantly higher than other points. The mean number of fungi in the aeration pond with 144 CFU/m3 had the highest concentration, and no fungal bioaerosol was observed 500 m downstream. Regarding the emission of H2S, CH4, and VOC gases, the anaerobic tank had the highest emission of these gases. 
Conclusion: Wastewater treatment plants (WWTPs) with activated sludge treatment technology and an aeration system can lead to an increase in the concentration of bacterial and fungal aerosols around the units and in surrounding areas.