Here are the answers to the Aug. 17, 2022 edition of TPO's Exam Study Guide:

What type of diffuser gives the best oxygen transfer but are less efficient at mixing?

The answer to the question is B, fine. Diffusers to provide aeration are very common throughout various wastewater treatment operations. Fine diffusers typically will produce 1-3 millimeter bubbles and have much greater oxygen transfer but are less efficient at mixing compared to coarse diffuser operations which produce larger 5-12 millimeter bubbles. When choosing the best diffuser for the treatment operation, the operator must determine what attribute is most important to his or her plant. There are many varieties of each available with all information needed to make the best choice.

What component helps prevent motor bearing damage from water leakage inside the stuffing box? 

The correct answer is B, slinger ring. The slinger ring is located towards the back of the stuffing box and is sometimes referred to as the deflector. There is always leakage occurring inside the stuffing box when mechanical packing is installed. Leakage may also occur inside the stuffing box when a mechanical seal fails. The water leaking in the stuffing box follows the shaft until contacting the slinger ring. Motor bearing damage is prevented by the slinger ring redirecting the water away from the electrical motor.


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