Tennessee Wastewater Operator Practice Exam

Decreasing the depth of a horizontal rotor's blade submergence will mainly result in what effect?

1. Increase the aeration efficiency

2. Decrease the noise during operation

3. Decrease the amount of power needed to operate the horizontal rotor

4. Increase the total dissolved solids

The correct answer is: Decrease the amount of power needed to operate the horizontal rotor

Decreasing the depth of a horizontal rotor's blade submergence primarily affects the power required for operation. As the depth decreases, the resistance encountered by the rotor reduces, leading to a decrease in the power needed to operate it effectively. This is largely due to the fact that less submerged area means less drag and turbulence in the fluid, allowing the rotor to operate more efficiently. While enhanced aeration or noise level changes may occur, the most direct and notable impact aligning with the decrease in submergence depth is the reduced power demand. This reduced resistance translates into lower operational costs and better energy efficiency for the wastewater treatment processes, ultimately making the system more sustainable over time.