Level 2 · Intermediate sample questions
3 free sample questions on headworks and screening for the Level 2 · Intermediate wastewater treatment operator exam. Try each one, then open the answer to check your work.
Screenings leaving a washer-compactor change from firm plugs to loose, wet material. Wash-water pressure is steady at 55 psi, screw speed is steady at 18 rpm, screw-drive torque remains normal at 65%, and discharge backpressure has fallen from 45 psi to 12 psi. What should the operator inspect first?
Answer: A. Check discharge-cone loading
Falling discharge backpressure from 45 psi to 12 psi with steady 55 psi wash water, 18 rpm screw speed, and normal 65% drive torque points to lost loading at the discharge cone. B checks a real wash-system cause of wet screenings, C checks a real compactor-wear cause, and D checks the conveyor drive, but none explains the pressure loss with otherwise normal compactor readings as directly.
An enclosed screenings chute begins plugging with wet material. Compactor output is steady at 18 ft³/hr, and conveyor current is steady at 12 A. At 8 min after a wash cycle ends, water still enters the chute and the idle spray-header pressure falls from 60 psi to 35 psi. What should the operator inspect first?
Answer: C. Check the spray-line shutoff
Water still entering 8 min after the wash cycle and idle header pressure falling from 60 psi to 35 psi point to a spray-line shutoff that is not sealing. A and B check real drive and screw causes of plugging, while D checks a real drainage cause, but none explains continued wash flow during the idle period.
A fine screen develops a fibrous mat on its discharge side. Spray pressure is steady at 65 psi, and screen speed is steady at 8 ft/min. A clearance check at the discharge edge measures 0.50 in on one side and 0.05 in on the other; the manufacturer maximum is 0.06 in across the width. What should the operator correct first?
Answer: A. Realign the discharge scraper
The 0.50 in discharge-edge gap exceeds the 0.06 in manufacturer maximum and is much larger than the 0.05 in gap on the other side, so the discharge scraper should be realigned. B adjusts channel hydraulics, C realigns the screen-drive chain, and D adjusts the wash system; all are nearby responses to screen matting, but the measured uneven clearance isolates scraper alignment.
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