Level 3 · Advanced sample questions
5 free sample questions on laboratory for the Level 3 · Advanced wastewater treatment operator exam. Try each one, then open the answer to check your work.
The lab accepts BOD bottles with at least 2.0 mg/L DO depletion and at least 1.0 mg/L final DO. Four bottles from one sample have these initial/final DO readings: Bottle 1: 8.4/6.8; Bottle 2: 8.2/4.0; Bottle 3: 8.1/0.6; and Bottle 4: 8.0/3.0 mg/L. Which bottle results should be averaged?
Answer: B. Bottles 2 and 4
A pH meter passes calibration at pH 4 and 7, but gives a stable high reading on two fresh pH 10 check buffers. Its temperature reading and compensation check pass. A second meter reads both buffers correctly. What should be evaluated before using the first meter for high-pH samples?
Answer: C. Electrode response above pH 7
An ammonia sample's matrix spike has low recovery. The calibration check, laboratory control sample, and a matrix spike on a different wastewater sample all pass. Which cause is most likely?
Answer: D. Interference from this sample's matrix
A laboratory SOP treats each group of four membrane-filtration samples as a separate batch and states that a failed closing blank invalidates that batch. The blank before Samples 1-4 is clean, but their closing blank has growth. Samples 5-8 use a new sterile setup and have clean opening and closing blanks. A valid repeat can be completed within holding time. Which samples require repeat analysis?
Answer: B. Samples 1-4 because their sterility check failed
A luminescent DO meter passes its zero check but fails an air-saturation check after being moved to a higher-elevation plant. Temperature is correct. The meter's pressure entry is 101.3 kPa, while a calibrated barometer at the plant reads 84.0 kPa. What should be corrected before repeating the check?
Answer: C. Enter the plant's barometric pressure
Keep practicing
Operator Master has 9 Level 3 · Advanced laboratory questions, free.
More topics