Tennessee Wastewater Operator Practice Exam

What effect do gas bubbles generated in the sludge blanket have?

1. Hastening sedimentation

2. Ashing or clumping

3. Improving oxygen transfer

4. Increasing settling velocity

The correct answer is: Ashing or clumping

Gas bubbles generated in the sludge blanket play a significant role in promoting the ashing or clumping of solids. When these bubbles form and rise through the sludge, they can cause small particles of solids to adhere to each other, creating larger aggregates or clumps. This agglomeration enhances the physical characteristics of the sludge, improving its handling and processing characteristics during wastewater treatment. The clumping also has functional advantages, such as potentially enhancing the overall settleability of sludge during sedimentation processes. However, the primary effect highlighted in this context refers specifically to the mechanisms by which bubbles facilitate the aggregation of suspended solids, leading to the formation of larger flocs within the sludge blanket. In comparison, the other options refer to different aspects of sludge behavior or characteristics not directly governed by the generation of gas bubbles in the same manner. For example, while gas bubbles might create turbulence that affects sedimentation rates, that is not their primary effect within the context of the question.