Free WW Equipment Operation, Maintenance, and Troubleshooting Questions and Answers

Question 1

What is the most common cause of cavitation in a centrifugal pump?

Accepted Answer

Suction lift is too high

Answer

Discharge valve is fully open

Answer

Pump is oversized for the application

Answer

Lubricant level is too low

Question 2

During routine maintenance on a positive displacement pump, what is a critical check to prevent poor performance and leaks?

Accepted Answer

Inspecting seals and packing for wear

Answer

Checking the motor's amperage draw

Answer

Verifying the discharge pressure gauge is calibrated

Answer

Painting the pump housing

Question 3

An operator notices a floating sludge blanket in a secondary clarifier. What is the most likely cause?

Accepted Answer

Denitrification occurring in the sludge blanket

Answer

Excessive influent flow (hydraulic overload)

Answer

Low influent BOD concentration

Answer

A broken scraper arm mechanism

Question 4

Which of the following is a primary indicator that a pump's bearings are failing?

Accepted Answer

Excessive heat and vibration

Answer

Lower than normal discharge pressure

Answer

A tripped circuit breaker

Answer

Air bubbles in the sight glass

Question 5

What is the primary purpose of a Lockout/Tagout (LOTO) procedure?

Accepted Answer

To isolate equipment from energy sources during maintenance

Answer

To track equipment inventory

Answer

To prevent unauthorized use of equipment after hours

Answer

To document the daily operational status of equipment

Question 6

If the dissolved oxygen (DO) level in an aeration basin is consistently low despite the blowers operating normally, what is a likely cause?

Accepted Answer

The air diffusers are clogged or fouled

Answer

The influent wastewater temperature is too low

Answer

The return activated sludge (RAS) rate is too high

Answer

The ambient air humidity is too high

Question 7

A mechanical bar screen repeatedly shuts down on high torque. What is the most probable cause?

Accepted Answer

Excessive debris or rags accumulating on the screen

Answer

Low influent flow

Answer

A faulty level sensor

Answer

Incorrect lubricant in the gearbox