Basic Wastewater Operator Practice Exam verified with correct answers
2026/2027 period
Calculate the BOD using the given information:
Initial DO: 8.3
Final DO: 5.9
Milliliters of sample used: 2
a. 360 mg/L
b. 210 mg/L
c. 856 mg/L
d. 36 mg/L- answer>>> >>>a. 360 mg/L
If your activated sludge plant begins to nitrify, what conditions would you expect to
decrease?
A. settling in clarifiers
B. chlorine demand
C. BOD effluent
D. TSS in effluent- answer>>> >>>a. settling in the clarifiers
How do you calibrate a chemical feed pump?
A. by measuring the pump output
B. using the SWAG method
C. jar test
D. with a microscope- answer>>> >>>A. by measuring the pump output
What is the chemical formula for sulfuric acid?
a. HNO3
b. HCl
c. NaOH
d. H2SO4- answer>>> >>>d. H2SO4
What is the most common type of activated sludge package plants?
a. extended aeration
b. sequential batch reactor
c. oxidation ditch
d. bardenpho- answer>>> >>>a. extended aeration
What is the most appropriate method of reducing the F:M ratio?
A. increase wasting
,b. decrease wasting
c. reduce BOD from influent flow
D. add polymer to RAS to increase settling- answer>>> >>>b. decrease wasting
An operator notices a portion of the aeration tank with large bubbles rising up. What is
the most likely problem?
a. equal air distribution
b. unequal air distribution caused by a blown/clogged diffuser
c. normal operation
d. reason to believe the air filter in the blower is clogged- answer>>> >>>b. unequal air
distribution caused by a blown diffuser
What is suction lift?
a. a team approach to lifting heavy objects
b. the pressure on the suction side of the pump
c. the measurement of liquid pressure at the pump
d. the measure of how bad your workers lift heavy objects- answer>>> >>>b. 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?
A. 290 mg/L
b. 60 mg/L
c. 30 mg/L
d. 22.5 mg/L- answer>>> >>>d. 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?
A. decrease the lag time for pump operation by moving the floats closer together
b. add pH adjuster to the influent flow
c. install larger capacity pumps in the lift stations
d. the her nothing you can do to correct this problem- answer>>> >>>A. decrease the
lag time for pump operation by moving the floats closer together
What is the purpose of amber storage bottles?
A. the color is pretty
b. they are cheaper
c. to protect chemicals that are sensitive to light
d. so you can not see what is inside the container- answer>>> >>>c. to protect
chemicals that are sensitive to light
, Calculate SRT
Given: MLSS = 2400 mg/L
Aeration basin volume = 35,000 gallons = 0.0350 MG
WAS concentration = 3500 mg/L
WAS flow rate = 0.001 MGD
A. 6 hours
b. 6 days
c. 24 hours
d. 24 days- answer>>> >>>d. 24 days
How should a 1-ton chlorine cylinder be moved and stored?
A. Horizontal and vertical
B. vertical and horizontal
C. vertical and vertical
D. horizontal and horizontal- answer>>> >>>D. horizontal and horizontal
Calculate F:M ratio
Given: Influent BOD5 = 290 mg/L
Influent flow = 5.0 MGD
Aeration basin MLSS = 2650 mg/L
Aeration basin volume = 0.8 MG
A. 0.01
B. 0.11
C. 0.68
D. 0.06- answer>>> >>>c. 0.68
What would most likely cause a submersible pump to an AMP reading that is above the
optimum level?
A. nothing, pumps normally run highs AMPs
b. clogged impeller
c. low voltage at power supply
d. low flow to pump station- answer>>> >>>b. clogged impeller
Which of the following are non-moving parts of a running motor?
A. impeller
b. shaft
c.windings
d. stator- answer>>> >>>d. stator
Calculate SVI
2026/2027 period
Calculate the BOD using the given information:
Initial DO: 8.3
Final DO: 5.9
Milliliters of sample used: 2
a. 360 mg/L
b. 210 mg/L
c. 856 mg/L
d. 36 mg/L- answer>>> >>>a. 360 mg/L
If your activated sludge plant begins to nitrify, what conditions would you expect to
decrease?
A. settling in clarifiers
B. chlorine demand
C. BOD effluent
D. TSS in effluent- answer>>> >>>a. settling in the clarifiers
How do you calibrate a chemical feed pump?
A. by measuring the pump output
B. using the SWAG method
C. jar test
D. with a microscope- answer>>> >>>A. by measuring the pump output
What is the chemical formula for sulfuric acid?
a. HNO3
b. HCl
c. NaOH
d. H2SO4- answer>>> >>>d. H2SO4
What is the most common type of activated sludge package plants?
a. extended aeration
b. sequential batch reactor
c. oxidation ditch
d. bardenpho- answer>>> >>>a. extended aeration
What is the most appropriate method of reducing the F:M ratio?
A. increase wasting
,b. decrease wasting
c. reduce BOD from influent flow
D. add polymer to RAS to increase settling- answer>>> >>>b. decrease wasting
An operator notices a portion of the aeration tank with large bubbles rising up. What is
the most likely problem?
a. equal air distribution
b. unequal air distribution caused by a blown/clogged diffuser
c. normal operation
d. reason to believe the air filter in the blower is clogged- answer>>> >>>b. unequal air
distribution caused by a blown diffuser
What is suction lift?
a. a team approach to lifting heavy objects
b. the pressure on the suction side of the pump
c. the measurement of liquid pressure at the pump
d. the measure of how bad your workers lift heavy objects- answer>>> >>>b. 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?
A. 290 mg/L
b. 60 mg/L
c. 30 mg/L
d. 22.5 mg/L- answer>>> >>>d. 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?
A. decrease the lag time for pump operation by moving the floats closer together
b. add pH adjuster to the influent flow
c. install larger capacity pumps in the lift stations
d. the her nothing you can do to correct this problem- answer>>> >>>A. decrease the
lag time for pump operation by moving the floats closer together
What is the purpose of amber storage bottles?
A. the color is pretty
b. they are cheaper
c. to protect chemicals that are sensitive to light
d. so you can not see what is inside the container- answer>>> >>>c. to protect
chemicals that are sensitive to light
, Calculate SRT
Given: MLSS = 2400 mg/L
Aeration basin volume = 35,000 gallons = 0.0350 MG
WAS concentration = 3500 mg/L
WAS flow rate = 0.001 MGD
A. 6 hours
b. 6 days
c. 24 hours
d. 24 days- answer>>> >>>d. 24 days
How should a 1-ton chlorine cylinder be moved and stored?
A. Horizontal and vertical
B. vertical and horizontal
C. vertical and vertical
D. horizontal and horizontal- answer>>> >>>D. horizontal and horizontal
Calculate F:M ratio
Given: Influent BOD5 = 290 mg/L
Influent flow = 5.0 MGD
Aeration basin MLSS = 2650 mg/L
Aeration basin volume = 0.8 MG
A. 0.01
B. 0.11
C. 0.68
D. 0.06- answer>>> >>>c. 0.68
What would most likely cause a submersible pump to an AMP reading that is above the
optimum level?
A. nothing, pumps normally run highs AMPs
b. clogged impeller
c. low voltage at power supply
d. low flow to pump station- answer>>> >>>b. clogged impeller
Which of the following are non-moving parts of a running motor?
A. impeller
b. shaft
c.windings
d. stator- answer>>> >>>d. stator
Calculate SVI
