BASIC WASTEWATER OPERATOR PRACTICE EXAM CLASS 3 |
QUESTIONS AND ANSWERS | 2026 UPDATE WITH COMPLETE
SOLUTION
What is the predominant organism in a healthy Activated Sludge Treatment
Plant? Answer - Stalked ciliates
A composite sample must be? Answer - Representative and Sub-samples time
spaced over 15 minutes apart
What is the standard volume for a BOD sample bottle? Answer - 300ml
If you have a lime slurry feed line, what is the best valve to use? Answer - Plug
valve
If you notice a predominance of rotifers in your activated sludge sample while
looking at it under a microscope, what does this indicate? Answer - Old Sludge
If your activated sludge plant begins to nitrify, what conditions would you
expect to decrease? Answer - Settling in the clarifiers
Calculate the BOD given the information:
Initial DO: 8.3
Final DO: 5.9
Milliliters of sample used: 2 Answer - 360mg/l
, How do you calibrate a chemical feed pump? Answer - By measuring the pump
output
What is the chemical formula for sulfuric acid? Answer - H2SO4
What is the most common type of Activated Sludge package plants? Answer -
extended aeration
What is the most appropriate method of reducing the F:M Ratio? Answer -
Increase wasting
An operator notices a portion of the aeration tank with large bubbles rising up.
What is the most likely problem? Answer - Unequal air distribution caused by a
blown diffuser
What is suction lift? Answer - The pressure on the suction side of the pump
The primary effluent to a RBC system is 350 mg/l BOD. The primary unit
removes 83%, the secondary unit removes 50%, and the final unit removes
25%. What is the BOD leaving the final unit of the RBC train? Answer - 22.5
mg/l
The influent to the treatment plant is septic. It is determined that it is coming
from a lift station upstream from the plant. What should the operator do?
Answer - Decrease the lag time for pump operation by moving the floats closer
together
What is the purpose of amber storage bottles? Answer - To protect chemicals
that are sensitive to light
QUESTIONS AND ANSWERS | 2026 UPDATE WITH COMPLETE
SOLUTION
What is the predominant organism in a healthy Activated Sludge Treatment
Plant? Answer - Stalked ciliates
A composite sample must be? Answer - Representative and Sub-samples time
spaced over 15 minutes apart
What is the standard volume for a BOD sample bottle? Answer - 300ml
If you have a lime slurry feed line, what is the best valve to use? Answer - Plug
valve
If you notice a predominance of rotifers in your activated sludge sample while
looking at it under a microscope, what does this indicate? Answer - Old Sludge
If your activated sludge plant begins to nitrify, what conditions would you
expect to decrease? Answer - Settling in the clarifiers
Calculate the BOD given the information:
Initial DO: 8.3
Final DO: 5.9
Milliliters of sample used: 2 Answer - 360mg/l
, How do you calibrate a chemical feed pump? Answer - By measuring the pump
output
What is the chemical formula for sulfuric acid? Answer - H2SO4
What is the most common type of Activated Sludge package plants? Answer -
extended aeration
What is the most appropriate method of reducing the F:M Ratio? Answer -
Increase wasting
An operator notices a portion of the aeration tank with large bubbles rising up.
What is the most likely problem? Answer - Unequal air distribution caused by a
blown diffuser
What is suction lift? Answer - The pressure on the suction side of the pump
The primary effluent to a RBC system is 350 mg/l BOD. The primary unit
removes 83%, the secondary unit removes 50%, and the final unit removes
25%. What is the BOD leaving the final unit of the RBC train? Answer - 22.5
mg/l
The influent to the treatment plant is septic. It is determined that it is coming
from a lift station upstream from the plant. What should the operator do?
Answer - Decrease the lag time for pump operation by moving the floats closer
together
What is the purpose of amber storage bottles? Answer - To protect chemicals
that are sensitive to light
