Level 3 · Advanced sample questions
3 free sample questions on headworks and screening for the Level 3 · Advanced wastewater treatment operator exam. Try each one, then open the answer to check your work.
One of two parallel bar screens has high headloss. Both channels carry similar flow. On the affected screen, rake motor current spikes at the same point near the top of every pass. Cycle timing and screenings load are normal. What should be checked first?
Answer: A. Rake drag and alignment at that point
The current spike repeats at the same rake position while flow and screenings load remain comparable. That pattern points to localized drag or misalignment at that point rather than a general hydraulic or timing problem.
A washer-compactor screw runs at normal current, but the discharge is wetter than usual. Wash-header pressure is normal, liquid pools in the compaction zone, and the filtrate sump level falls. What should be inspected first?
Answer: B. Drainage openings
Normal screw current and normal wash-header pressure rule out the drive load and common wash supply. Pooling in the compaction zone while the filtrate sump level falls points to restricted drainage openings; the nozzle pattern, discharge cone, and screw-flight clearance do not fit both readings.
A screenings washer-compactor sends excess wash water into its discharge chute. Screw speed and torque are normal. After the wash command ends, the branch flowmeter remains at 18 gpm, while a parallel wash branch falls to 0 gpm. What should be checked first?
Answer: C. Wash-valve control
Normal screw speed and torque rule out the compactor drive. The affected branch remaining at 18 gpm after the command ends while the parallel branch falls to 0 gpm localizes the problem to its wash-valve control; flow split, screen level, and screw wear do not fit both readings.
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