Texas Wastewater Class B Practice Exam

Which observation indicates that an operator should adjust the air SCFM in an aeration tank?

1. Uneven surface aeration

2. High temperature in the tank

3. Clear effluent outflow

4. Frequent solids settling

The correct answer is: Uneven surface aeration

Adjusting the air standard cubic feet per minute (SCFM) in an aeration tank is particularly important when there are signs of uneven surface aeration. This observation can indicate that the distribution of air in the tank is not optimal, potentially leading to poor mixing and inadequate oxygen transfer for the microorganisms responsible for breaking down organic matter. When aeration is uneven, some areas of the tank may receive too much air, while others may not receive enough, affecting the overall effectiveness of the treatment process. Monitoring for uniform aeration is critical because inconsistent oxygen levels can stress the biological treatment processes, affecting the performance of the system and leading to suboptimal effluent quality. Adjusting the SCFM can help ensure that the aeration system operates efficiently, providing adequate oxygen and mixing throughout the tank. High temperature in the tank, clear effluent outflow, and frequent solids settling can each indicate other issues. For instance, high temperatures may influence microbial activity but do not directly necessitate changes to air flow. Clear effluent suggests that sedimentation processes are effective, and frequent solids settling might indicate that settling behavior is within acceptable limits, but does not specifically point to aeration issues. Focusing on the observation of uneven surface aeration directs attention to the immediate need