Tennessee Wastewater Operator Practice Exam

What is a significant advantage of using smaller bubbles in aeration processes?

1. Decreased surface area

2. Better oxygen transfer rates

3. Increased turbulence in the tank

4. Higher operational costs

The correct answer is: Better oxygen transfer rates

Using smaller bubbles in aeration processes significantly enhances oxygen transfer rates, which is crucial for effective wastewater treatment. The primary reason for this advantage is that smaller bubbles have a larger surface area-to-volume ratio compared to larger bubbles. This increased surface area allows for more efficient gas exchange, enabling a greater amount of oxygen to dissolve into the water as the bubbles rise. Additionally, smaller bubbles tend to have a more extended residence time in the liquid, allowing the oxygen they contain to be released more effectively. This characteristic is essential when dealing with wastewater, where sufficient dissolved oxygen is necessary for aerobic bacteria to thrive and break down organic matter. In contrast, larger bubbles may rise too quickly to facilitate effective oxygen transfer and may not provide the same beneficial effects on microbial activity. Furthermore, the operational costs associated with using smaller bubbles are generally lower, as they can be generated using less energy due to their more efficient aeration capabilities. This, combined with better oxygen transfer, makes the use of smaller bubbles a desirable practice in wastewater treatment processes.