Page 1 of 121
Nevada Wastewater Treatment Plant Operator Grade II Exam
COMPLETE QUESTIONS AND DETAILED SOLUTIONS LATEST
UPDATE THIS YEAR-JUST RELEASED
SUMMARIZED EXAM COVERAGE
Nevada Grade II wastewater exams cover regulations, NPDES permits, reporting, and operator
responsibilities. Major focus is on math conversions, flow calculations, and the pounds formula. You
must understand lab tests such as BOD, TSS, DO, pH, ammonia, and chlorine residual. Treatment topics
include preliminary and primary treatment, activated sludge process control (MLSS, RAS, WAS, sludge
age, SVI, bulking/foaming), trickling filters/RBCs, clarifiers, disinfection (chlorine/UV/dechlorination),
and sludge thickening/digestion/dewatering. Equipment knowledge includes pumps, blowers, motors,
calibration, and troubleshooting. Safety is heavily tested, especially confined space, H2S, chlorine,
lockout/tagout, and emergency spill response.
1.
An operator measures influent flow at 2.5 MGD and influent BOD at 180 mg/L. What is the approximate
BOD load in pounds per day?
A. 375 lbs/day
B. 1,875 lbs/day
C. 3,753 lbs/day
D. 7,506 lbs/day
, Page 2 of 121
Answer: C
Rationale: lbs/day = MGD × mg/L × 8.34 = 2.5 × 180 × 8.34 ≈ 3,753 lbs/day.
2.
A secondary clarifier begins showing cloudy effluent and rising sludge blanket depth. Which immediate
operational adjustment is most appropriate?
A. Stop wasting sludge completely for three days
B. Increase RAS rate to return solids to aeration basin
C. Reduce influent flow by closing plant headworks
D. Add chlorine directly into the secondary clarifier
Answer: B
Rationale: Increasing RAS helps control blanket depth and reduces solids carryover in the effluent.
3.
An operator detects a strong rotten egg odor near a wet well, and the gas monitor alarms. Which gas is
most likely present?
A. Oxygen
B. Hydrogen sulfide
, Page 3 of 121
C. Nitrogen
D. Carbon dioxide
Answer: B
Rationale: Hydrogen sulfide has a rotten egg smell and is common in anaerobic wastewater
environments.
4.
A plant’s effluent chlorine residual remains low even after increasing chlorine feed. What is the most
likely cause?
A. High chlorine demand from organic matter or ammonia
B. Too much dissolved oxygen in the contact chamber
C. Low turbidity in the effluent
D. Excessive MLSS in the aeration tank
Answer: A
Rationale: High ammonia or organics increase chlorine demand, reducing measurable residual.
5.
, Page 4 of 121
A pump begins making a loud gravel-like sound and loses discharge pressure. Which condition is most
likely occurring?
A. Cavitation due to low suction head or clogged intake
B. Electrical short circuit inside the motor
C. Excessive sludge age in aeration basin
D. Too much chlorine in the wet well
Answer: A
Rationale: Cavitation creates noise and reduces pump efficiency, often caused by suction problems.
6.
A sample bottle for BOD testing is left unpreserved in a warm room for eight hours before testing. What
is the biggest problem?
A. BOD result will likely be falsely low due to oxygen gain
B. BOD result will likely be inaccurate because bacteria continue consuming oxygen
C. pH will always increase above 10.0
D. Chlorine residual will become artificially high
Answer: B
Rationale: Microbial activity continues after collection, altering oxygen demand and compromising test
accuracy.
Nevada Wastewater Treatment Plant Operator Grade II Exam
COMPLETE QUESTIONS AND DETAILED SOLUTIONS LATEST
UPDATE THIS YEAR-JUST RELEASED
SUMMARIZED EXAM COVERAGE
Nevada Grade II wastewater exams cover regulations, NPDES permits, reporting, and operator
responsibilities. Major focus is on math conversions, flow calculations, and the pounds formula. You
must understand lab tests such as BOD, TSS, DO, pH, ammonia, and chlorine residual. Treatment topics
include preliminary and primary treatment, activated sludge process control (MLSS, RAS, WAS, sludge
age, SVI, bulking/foaming), trickling filters/RBCs, clarifiers, disinfection (chlorine/UV/dechlorination),
and sludge thickening/digestion/dewatering. Equipment knowledge includes pumps, blowers, motors,
calibration, and troubleshooting. Safety is heavily tested, especially confined space, H2S, chlorine,
lockout/tagout, and emergency spill response.
1.
An operator measures influent flow at 2.5 MGD and influent BOD at 180 mg/L. What is the approximate
BOD load in pounds per day?
A. 375 lbs/day
B. 1,875 lbs/day
C. 3,753 lbs/day
D. 7,506 lbs/day
, Page 2 of 121
Answer: C
Rationale: lbs/day = MGD × mg/L × 8.34 = 2.5 × 180 × 8.34 ≈ 3,753 lbs/day.
2.
A secondary clarifier begins showing cloudy effluent and rising sludge blanket depth. Which immediate
operational adjustment is most appropriate?
A. Stop wasting sludge completely for three days
B. Increase RAS rate to return solids to aeration basin
C. Reduce influent flow by closing plant headworks
D. Add chlorine directly into the secondary clarifier
Answer: B
Rationale: Increasing RAS helps control blanket depth and reduces solids carryover in the effluent.
3.
An operator detects a strong rotten egg odor near a wet well, and the gas monitor alarms. Which gas is
most likely present?
A. Oxygen
B. Hydrogen sulfide
, Page 3 of 121
C. Nitrogen
D. Carbon dioxide
Answer: B
Rationale: Hydrogen sulfide has a rotten egg smell and is common in anaerobic wastewater
environments.
4.
A plant’s effluent chlorine residual remains low even after increasing chlorine feed. What is the most
likely cause?
A. High chlorine demand from organic matter or ammonia
B. Too much dissolved oxygen in the contact chamber
C. Low turbidity in the effluent
D. Excessive MLSS in the aeration tank
Answer: A
Rationale: High ammonia or organics increase chlorine demand, reducing measurable residual.
5.
, Page 4 of 121
A pump begins making a loud gravel-like sound and loses discharge pressure. Which condition is most
likely occurring?
A. Cavitation due to low suction head or clogged intake
B. Electrical short circuit inside the motor
C. Excessive sludge age in aeration basin
D. Too much chlorine in the wet well
Answer: A
Rationale: Cavitation creates noise and reduces pump efficiency, often caused by suction problems.
6.
A sample bottle for BOD testing is left unpreserved in a warm room for eight hours before testing. What
is the biggest problem?
A. BOD result will likely be falsely low due to oxygen gain
B. BOD result will likely be inaccurate because bacteria continue consuming oxygen
C. pH will always increase above 10.0
D. Chlorine residual will become artificially high
Answer: B
Rationale: Microbial activity continues after collection, altering oxygen demand and compromising test
accuracy.
