Wastewater Treatment Operator Certification Practice Test

Which of the following is a common consequence of inadequate aeration in the activated sludge process?

1. Sewage odors

2. Low BOD removal

3. Excessive foam production

4. Rapid sludge settling

The correct answer is: Low BOD removal

Inadequate aeration in the activated sludge process primarily leads to low biological oxygen demand (BOD) removal. This occurs because aeration is crucial for providing the microorganisms in the activated sludge with the oxygen they need to effectively break down organic matter in the wastewater. When there is insufficient aeration, these microorganisms cannot thrive, resulting in reduced efficiency for the treatment process. Consequently, the BOD levels in the effluent remain higher than desired, indicating less effective treatment and more pollutants present in the water being discharged. While odors can be a consequence of various issues, including poor aeration, they are not the primary or most direct result of inadequate oxygen levels. Excessive foam production can also occur due to various factors such as surfactants or other foaming agents in the wastewater rather than solely due to aeration issues. Rapid sludge settling can be influenced by several factors and is not a direct result of insufficient aeration either; in fact, good aeration typically promotes better settling characteristics by improving microbial floc formation. Thus, the direct link between inadequate aeration and low BOD removal makes that the most accurate outcome of the options provided.