The generation characteristics, pattern, and exposure risk of bioaerosol emitted in an A²O process wastewater treatment plant

Abstract

Bioaerosols can be generated in wastewater treatment plants (WWTPs), they may contain pathogenic bacteria, cause disease transmission, and attract the public’s attention. In this study, bioaerosols were collected from seven different stages of an A²O process WWTP. The component characteristics were analyzed by bacterial culture and high-throughput sequencing. The correlations in different processes were analyzed, and the health risks of bioaerosols produced were evaluated. The results showed that the concentration range of bacteria aerosol in the WWTP was 75 CFU/m³−706 CFU/m³. The concentration range of total suspended particles was 111.13 µg/m³−211.67 µg/m³, the primary water-soluble ions were Ca²⁺ and Cl⁻. In the air of each stage, the main bacteria were Cetobacterium, Bacteroides, Romboutsia, and the fungi were Fusarium, Alternaria, and Aspergillus. The dominant bacteria in the wastewater were Cetobacterium, Romboutsia, Stenotrophobacter, and the fungi were Fusarium, Aspergillus, and Mortierella. The total bacterial concentration and ion concentration in the aerobic section of the biochemical tank were the highest. The results of species composition and principal component analysis showed that the bacterial composition in the air at different processes was similar, while the bacteria in wastewater differed significantly. Among them, the wastewater bacteria in the aerobic section of the biochemical tank were closer to that in the air. Fungal results were similar to bacteria but not prominent. The bioaerosol exposure risk results show that the risk in each stage was acceptable (5.15 ×10⁻⁴−6.47 ×10⁻³). However, the exposure risk of bioaerosol was calculated by the total bacterial concentration. In fact, some pathogenic microorganisms such as Escherichia coli and Aspergillus flavus were detected in bioaerosols, which may cause hemorrhagic colitis, cancer and other diseases by swallowing and inhalation. Therefore, the risk might be underestimated and should be a cause of concern.

Keywords

• Bioaerosol
• Wastewater treatment process
• Generation characteristic
• Microbial population
• Exposure risk