Level 3 · Advanced sample questions
5 free sample questions on solids handling for the Level 3 · Advanced wastewater treatment operator exam. Try each one, then open the answer to check your work.
A belt press makes wetter cake after maintenance. Feed solids and polymer drawdown are steady. Wash-water pressure is normal, but the belt wanders toward one edge and the measured tension changes each pass. Which part should be checked first?
Answer: C. Belt tracking and tension
A centrifuge ran smoothly before a power failure stopped it without its normal rinse. At the next startup, it trips on high vibration before sludge feed begins. Speed is normal, bearing lubrication checks are satisfactory, and the mounting bolts are tight. What is the most likely cause?
Answer: A. Uneven solids left in the bowl
A DAF thickener produces dilute float after its flocculator speed is increased. Recycle pressure and air saturation remain normal. Tests using the current polymer dose produce strong floc with gentle mixing, but plant floc breaks apart before entering the DAF. What adjustment best addresses the cause?
Answer: C. Reduce the excessive flocculator mixing
A DAF system produces few bubbles at the recycle release. Recycle flow is normal, a second gauge confirms normal saturator pressure, and the release nozzle is clear. Which part of the recycle system should be checked next?
Answer: D. Air supply and addition to the saturator
A centrifuge's cake becomes wetter after sludge feed flow is increased. Feed solids concentration and polymer dose per dry ton are unchanged. Torque control keeps raising the scroll differential speed to prevent overload. Which adjustment best addresses the new condition?
Answer: B. Reduce sludge feed toward the previous rate
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