Tennessee Wastewater Operator Practice Exam

In a mechanically aerated facultative pond system, what should be done if DO concentrations are consistently below acceptable levels?

1. Increase the influent flow rate

2. Consider switching to parallel operation

3. Reduce the aeration intensity

4. Change the type of wastewater processed

The correct answer is: Consider switching to parallel operation

In a mechanically aerated facultative pond system, maintaining adequate dissolved oxygen (DO) levels is crucial for promoting the aerobic digestion necessary for effective wastewater treatment. When DO concentrations are consistently below acceptable levels, it indicates that the current operational configuration may not be meeting the oxygen demands of the system. Considering switching to parallel operation can help address this issue. Parallel operation involves using multiple aeration units or ponds simultaneously, which can enhance the overall aeration capacity and improve oxygen transfer efficiency across the treatment system. By distributing the oxygen demands across multiple units, each can be operated at optimal conditions, potentially leading to increased DO levels in the overall system. Increasing the influent flow rate could further dilute the existing DO concentration without addressing the oxygenation issue directly. Reducing aeration intensity may exacerbate the problem, as less aeration would likely further decrease DO levels. Changing the type of wastewater processed may not be a practical or immediate solution to the problem at hand, especially if the existing processes are designed to handle specific types of wastewater. Therefore, considering operational strategies like parallel operation is a logical and effective response when dealing with low DO levels in a mechanically aerated facultative pond system.