Tennessee Wastewater Operator Practice Exam

What triggers flooding in a mechanical aerator equipped with a draft tube?

1. Increased inflow of wastewater

2. Draft tube flow direction is reversed

3. Malfunction of the aerator's motor

4. Blockage in the aerator system

The correct answer is: Draft tube flow direction is reversed

Flooding in a mechanical aerator equipped with a draft tube is primarily triggered by a reversal of the draft tube flow direction. The draft tube is designed to carry the effluent product of aeration away from the aerator while ensuring that air is drawn into the system. If the flow direction becomes reversed, this can cause the influent wastewater to be forced back into the aerator chamber instead of exiting as it should. This reversal effectively disrupts the intended flow dynamics within the system, leading to potential flooding as the volume of incoming wastewater continues to accumulate without proper discharge. Understanding the role of the draft tube in the aeration process is crucial for wastewater operators. The flow direction is integral to maintaining operational efficiency and preventing excess water build-up, which could compromise the system's functionality and lead to further operational issues.