Bioaerosol Emissions of Bacillus anthracis Surrogate Spores from Aqueous Media
Citation:
Burdsall, A. Bioaerosol Emissions of Bacillus anthracis Surrogate Spores from Aqueous Media. Wright State University Colloquium, Virtual, OH, October 21, 2021.
Impact/Purpose:
This is a presentation on bioaerosols in wastewater plants, presented to the Wright State University Colloquium. Bioaerosols are emitted from aeration tanks in wastewater treatment plants (WWTPs) can be carried far from their site of origin, risking the health of operators and the general public. This presentation outlines the work done at the Air Force Institute of Technology and the Testing & Evaluation facility at several scales that has been published in the Xing et al., 2021 publication in Environmental Science: Water Research and Technology.
Description:
We studied bioaerosol release using Bacillus globigii spores at three scales as well as the effectiveness of the potential bioaerosol mitigation strategy, free-floating carrier media (FFCM), to suppress bioaerosol emission. We studied both physical and diffusion aeration methods with Bacillus globigii spores as the sole microorganisms in well-defined liquid media. The percentage of the reactor captured was very low, but consisted of many colony forming units. Physical . Physical mixing methods seemed to show an exponential increase in the aerosol release rate as stirring rate increased linearly. Fine bubble aeration produced many bioaerosols, often more than stirring. Of the FFCM tested, polystyrene was the most effective, reducing bioaerosol release by > 92% in the bench-scale studies and >74% in the pilot-scale study. Parameter analysis revealed a strong correlation (R2>0.82) between bioaerosol release and the superficial gas velocity, the Froude number, and the volumetric gas flow per unit liquid volume per minute; by contrast, the Reynolds number was found to be poorly correlated with bioaerosol release (R2 <0.5). Future work planned at EPA’s Testing & Evaluation facility will expand the work with Bacillus anthracis surrogates to include viral surrogates. Physical mixing methods seemed to show an exponential increase in the aerosol release rate as stirring rate increased linearly. Fine bubble aeration produced many bioaerosols, often more than stirring. Of the FFCM tested, polystyrene was the most effective, reducing bioaerosol release by > 92% in the bench-scale studies and >74% in the pilot-scale study. Parameter analysis revealed a strong correlation (R2>0.82) between bioaerosol release and the superficial gas velocity, the Froude number, and the volumetric gas flow per unit liquid volume per minute; by contrast, the Reynolds number was found to be poorly correlated with bioaerosol release (R2 <0.5). Future work planned at EPA’s Testing & Evaluation facility will expand the work with Bacillus anthracis surrogates to include viral surrogates.