[Particle Size Distribution and Population Characteristics of Airborne Bacteria Emitted from a Sanitary Landfill Site].

Sanitary landfill is a commonly-used method for solid waste disposal. In the process of landfilling, e. g. dumping, stacking, pushing, and compacting, a large number of bioaerosols with pathogenic bacteria will be generated. That can result in air pollution and significant harm to human health if these pathogens are released into the air. Sampling sites were set up in a domestic waste sanitary landfill in North China to collect airborne bacteria in the air. Airborne bacteria, particle size distributions, and populations were analyzed, and the influence of meteorological parameters (temperature, relative humidity (RH), and wind speed (WS)) on the emission of airborne bacteria was also investigated. Results showed that the concentrations of airborne bacteria in the working area and the coverage area were (5437±572) CFU·m-3 and (2707±396) CFU·m-3, respectively. The emission level in the leachate treatment area was the highest, with an average of 9460 CFU·m-3. The concentration of airborne bacteria showed clear seasonal variation, being was much higher in summer than that in the other seasons. Redundancy analysis (RDA) demonstrated that RH, temperature, and WS affected the number of airborne bacteria in the air. The peaks in the airborne particle size distribution were 2.1-4.7 µm in the working area and 0.65-2.1 µm in the coverage area. Most of the airborne bacteria released from the leachate treatment processes were larger than 4.7 µm. Moraxellaceae, Bacillus aerius, Arcobacter, and Aeromonas were potential or opportunistic pathogens detected from the airborne bacteria samples. Effective measures should be taken to reduce the amount of bacterial aerosol emitted to the air in landfill working areas and in the leachate of treatment areas. Operators of landfill machinery and leachate treatment facilities should consider personal protection measures and should reduce their exposure to microbial aerosols in order to prevent disease.

[Characteristics of Bioaerosols Emitted from WWTP with SBR Treatment Process].

Sampling sites were located in a wastewater treatment plant (WWTP) with a sequencing batch reactor activated sludge process to investigate the characteristics of bioaerosol emissions. The results indicated that bioaerosols were detected from each treatment section of the WWTP, and concentrations of bioaerosols were in the range of 82-1525 CFU·m-3. The coarse screen, aeration tank, and sludge dewatering house were the main sources of bioaerosols. The dominant species in each treatment section was Cyanobacteria, and the other main bacterial taxa were Aeromonas, Peptostreptococcaceae, Moraxellaceae, Chroococcidiopsis, Sphingomonas, Arcobacter, and Acinetobacter. Among the identified bacterial genera, Aeromonas, Arcobacter, Acinetobacter, and Sphingomonas were potential pathogens. Bioaerosol concentration and abundance decreased along the vertical and horizontal directions. Appropriate temperature and relative humidity benefited the survival of bioaerosols in the air (P<0.01), whereas a negative relationship between bioaerosol concentration and wind speed was observed (P<0.05). Although exposure risks caused by bioaerosols were negligible in this study, the accumulation of bioaerosols would increase potential health risks. The bioreactor for odor treatment could effectively reduce bioaerosol emissions.