Texas Wastewater Class B Practice Exam

In an activated sludge system, what does excessive air flow suggest?

1. Clogged air diffusers

2. Low hydraulic loading

3. Too much biomass

4. Leakage in the aeration system

The correct answer is: Leakage in the aeration system

Excessive air flow in an activated sludge system can often indicate a leakage in the aeration system. When there are leaks, more air is required to maintain the desired aeration level, which can result in an increase in the total air flow supplied. This not only suggests inefficiencies in the system but can also lead to increased operational costs. While clogged air diffusers might cause reduced air flow, leading to the impression of needing excessive air flow, they do not directly cause it. Low hydraulic loading would typically require less air flow, as there's less wastewater for treatment. Too much biomass can lead to other issues, such as poor oxygen transfer rates, but would not specifically cause excessive air flow on its own. Thus, identifying a leakage is crucial for ensuring the system operates at optimal conditions.