Aeration tanks in wastewater treatment plants (WWTPs) are significant sources of bioaerosols, which contain microbial contaminants and can travel miles from the site of origin, risking the health of operators and the general public. One potential mitigation strategy is to apply free-floating carrier media (FFCM) to suppress bioaerosol emission. This article presents a multiscale study on the effects of mixing and FFCM on bioaerosol release using Bacillus globigii spores in well-defined liquid media. Bioaerosol release, defined as percentage of spores aerosolized during a 30 minute sampling period, ranged from 6.09 × 10⁻⁷% to 0.057%, depending upon the mixing mode and intensity. Bioaerosol release increased with the intensity of aeration (rotating speed in mechanical agitation and aeration rate in diffused aeration). A surface layer of polystyrene beads reduced bioaerosol released by >92% in the bench-scale studies and >74% in the pilot-scale study. This study discovered strong correlations (R² > 0.82) between bioaerosol release and superficial gas velocity, Froude number, and volumetric gas flow per unit liquid volume per minute. The Reynolds number was found to be poorly correlated with bioaerosol release (R² < 0.5). This study is a significant step toward the development of predictive models for full scale systems.

中文翻译：

---

混合和自由漂浮载体介质对废水中生物气溶胶释放的影响：球芽孢杆菌的多尺度研究

废水处理厂 (WWTP) 中的曝气池是生物气溶胶的重要来源，这些生物气溶胶含有微生物污染物，并且可以从源头传播数英里，危及操作人员和公众的健康。一种潜在的缓解策略是应用自由浮动载体介质（FFCM）来抑制生物气溶胶排放。本文介绍了在明确的液体介质中使用球芽孢杆菌孢子进行混合和 FFCM 对生物气溶胶释放的影响的多尺度研究。生物气溶胶释放（定义为在 30 分钟采样期间雾化的孢子百分比）范围为 6.09 × 10 ^-7 % 至 0.057%，具体取决于混合模式和强度。生物气溶胶释放随着曝气强度（机械搅拌中的转速和扩散曝气中的曝气速率）而增加。在小规模研究中，聚苯乙烯珠表面层可将生物气溶胶释放量减少 92% 以上，在中试规模研究中减少 74% 以上。这项研究发现生物气溶胶释放与表观气体速度、弗劳德数和每分钟每单位液体体积的体积气体流量之间存在很强的相关性（R ² > 0.82）。发现雷诺数与生物气溶胶释放的相关性较差（R ² < 0.5）。这项研究是朝着开发全尺寸系统预测模型迈出的重要一步。