Basic Wastewater Operator Practice Exam

An operator notices a portion of the aeration tank with large bubbles rising up. What is the most likely problem?

1. Equal air distribution

2. Unequal air distribution caused by a blown/clogged diffuser

3. Normal operation

4. Air filter in the blower is clogged

The correct answer is: Unequal air distribution caused by a blown/clogged diffuser

When observing large bubbles rising in a portion of the aeration tank, the most likely issue is caused by unequal air distribution, which can be attributed to a blown or clogged diffuser. Diffusers play a crucial role in aeration systems by distributing air evenly throughout the tank, providing critical oxygen for the microorganisms responsible for breaking down organic matter. If a diffuser is either damaged or blocked, it can lead to an uneven flow of air, creating areas of high bubble formation and low oxygen transfer efficiency. This scenario would not typically be considered normal operation, as it indicates an inefficiency in the aeration process that could potentially disrupt the biological treatment processes. Additionally, while a clogged air filter in the blower could cause airflow problems, it would primarily affect the overall air supply rather than lead to localized large bubbles in a specific area of the aeration tank. On the other hand, proper air distribution is fundamental to ensuring consistent mixing and oxygenation throughout the tank, which is why recognizing issues related to diffusers is essential for maintaining effective wastewater treatment.