Characteristics of airborne microorganisms in wastewater treatment plant

Airborne microorganisms in four different units (rack chamber, aeration tank, sludge thickening tank and sludge dewatering facility) in certain wastewater treatment plant in Beijing were chosen as research object and their distribution characteristics were studied. Results showed that the concentrations of heterotrophic bacteria and fungi in different units had significant differences. The aeration tank unit had the highest concentrations of heterotrophic bacteria and fungi, followed by the sludge dewatering facility unit and the rack chamber unit, and the lowest was in sludge thickening tank. The size distributions of the heterotrophic bacteria in the four different units had no significant difference, and the highest proportions of the size distribution were in the stage 2, stage 3, stage 4 and stage 5. While, the size distribution of fungi was different from that of heterotrophic bacteria, and the highest proportions of the size distribution were in the stage 3, stage 4 and stage 5. It was noteworthy that 30%-33% of heterotrophic bacteria and 31%-37% of fungi were carried by particle with a diameter size of 0.65-2.1 μm, which could reach the alveolus and thus pose a major threat to human health.