Airborne bacteria and fungi in a wastewater treatment plant: type and characterization of bio-aerosols, emission characterization and mapping

Exposure to bioaerosols causes infection, over-sensitivity, respiratory, and lung diseases. This study was conducted at Sanandaj wastewater treatment plant in three seasons of winter, spring and summer to investigate the type and density of bio-aerosols. Sampling was performed using a sampling pump with a discharge rate of 28.3 L/min at a height of 1.5 m above the ground; the samples were taken from five stations: treatment plant entrance, aeration tank, grit chamber, drying sludge bed and laboratory. At each sampling point, time, temperature, relative humidity (Soleimani et al.), wind speed and particulate matter were recorded. In order to identify the bacteria, polymerase chain reaction (PCR) and culture-based methods were applied. It was also found that there was not a significant relationship between bacterial count and RH, wind direction, wind speed and temperature. Regarding fungi, the results showed that RH and wind direction and wind has a significant relationship with the concentration of fungi. The most predominant bacteria and fungi were as follows: Staphylococcus, Enterobacteriaceae, Bacillus, Acinetobacter, Micrococcus, Enterococcus, Neisseria, Listeria, and Pseudomonas and Penicillium, Aspergillus flavus. The concentration of bacteria in the air was significantly correlated with < 4, < 5, < 7 and < 10 μm suspended particles. However, there was a correlation between particle number of 10 μm and fungi concentration in the air.