Comparison of the density and composition of bacteria and fungi in the air of anoxic and aeration tanks in the wastewater treatment plant

Abstract

Abstract The bioaerosols from the wastewater treatment plant can be propagated into the air, affecting the health of residents, animals, and plants around the area. This study was conducted to evaluate the density and composition of bioaerosols (bacteria and fungi) in anoxic and aeration tanks of a domestic wastewater treatment plant. Bioaerosol samples were taken by the active method with SKC Biostage. The agar dishes were placed at a height of 1.5 m above the ground. After sample collection, the dishes were incubated at 37 ±1 °C for 24h-48h for bacteria and at 25 ±1 °C for 72h-120h for fungi. Then, these microorganisms were identified by 16S rRNA (16S Metabarcoding) method for bacteria and taxonomy method for fungi. The results showed that the density of bacteria and mold in the anoxic tank ranged from 233.2 ±7.8 to 339.2 ±13.9 CFU/m3 and 91.8 ±3.2 to 197.9 ±10.1 CFU/m3, respectively. Meanwhile, bacterial and mold densities of aeration tank ranged from 275.6 ±10.4 to 424.0 ±17.3 CFU/m3 and 176.7 ±5.8 to 254.4 ±12.1 CFU/m3, respectively. The density of bacteria and mold in the aeration tank is higher than in the anoxic tank. On the other hand, the 16S Metabarcoding analysis for the microbial diversity detects more than 100 species in two tanks, the predominant bacterial species are: Bacillus megaterium (B. megaterium), Bacillus cereus (B. cereus), Staphylococcus sciuri (S. sciuri) and two common fungi Aspergillus tamarii (A. tamarii), and Penicillium rubers (P. rubers). This preliminary survey in Viet Nam reveals the existence and diversity of bioaerosols in the air from the biological treatment tanks of the wastewater treatment plant.