Basic Wastewater Operator Practice
Exam Questions and answers | Updated
2025 RATED A+
What is the predominant organism in a healthy activated sludge treatment plant?
II II II II II II II II II II II
A. Stalked ciliates
II II
B. rotifersII
C. nematodesII
D. amoebas A. Stalked iliates
II II II II II II II
II A composite sample must be?
II II II II
A. sporadically collected in the treatment plant
II II II II II II
B. taken at one time
II II II II
C. analyzed immediately
II II
D. representative and sub-samples time spaced over
II minutes apart II II II II II II II II II D.
II II II
representative and sub-samples time spaced over
II minutes apart II II II II II II II I
W hat is the standard volume for a BOD sample bottle?
II II II II II II II II II II
A. II II
B. II II
C. II II
D. II II II II II II c. II II
If you have a lime slurry feed line, what is the best valve to use?
II II II II II II I II II II II II II II II
A. plug valve
II II
B. butterfly valve
II II
C. PZ dual check valve
II II II II
D. gate valve A. plug valve
I II II II II II II II
5. If you notice a predominance of rotifers in your activated sludge sample while looking at
II II II II II II I I II II II II II II II II
it under a microscope, what does this indicate
II II II II II II II II
A. healthy sludge
II II
B. young sludge
II II
C. old sludge
II II
D. middle age sludge
II II II II C. old sludge
II II II II II
IIalculate the BO using the given information: II II II II II II
Initial O: . II II
,Final O: . II II
a. II mg/ II
b. II mg/ II
c. II mg/ II
d. I mg/
II II II II II a. II II mg/
If your activated sludge plant begins to nitrify, what conditions would you expect to
II II II II II II I II II II II II II I
decrease
II
A. settling in clarifiers
II II II
B. chlorine demand
II II
C. BO effluent II II
D. TSS in effluent a. settling in the clarifiers
II II II II II II II II II II I
II How do you calibrate a chemical feed pump?
II II II II II I II
A. by measuring the pump output
I II II II II
B. using the SWAG method
II II II II
C. jar test II II
D. with a microscope A. by measuring the pump output
I II II II II II II II II II II II
W hat is the chemical formula for sulfuric acid?
II II II II II II II II
a. O II
b. l II
c. aO II
d. SO II II II II II d. II SO
W hat is the most common type of activated sludge package plants?
II II II II II II II II II II II
a. extended aeration
II II
b. sequential batch reactor
II II II
c. oxidation ditch
II II
d. bardenpho a. extended aeration
II II II II II II I
W hat is the most appropriate method of reducing the F:M ratio?
II II II II I II II II II I II
A. increase wasting
II II
b. decrease wasting
II II
c. reduce BO from influent flow
II II II II II
D. add polymer to AS to increase settling
II II II II II II II II II II II b. decrease wasting
II II
An operator notices a portion of the aeration tank with large bubbles rising up. W hat is the
II I II II I II II I II I II II II II II II II
most likely problem
II II II
, a. equal air distribution
II II II
b. unequal air distribution caused by a blown/clogged diffuser
II II II II II II II II
c. normal operation
II II
d. reason to believe the air filter in the blower is clogged b. unequal air distribution
I I II II II I II II II II II I II II II II II II
caused by a blown diffuser
II II II II II
W hat is suction lift?
II II II I
a. a team approach to lifting heavy objects
I II II II II II II
b. the pressure on the suction side of the pump
I II II II II II II II II
c. the measurement of liquid pressure at the pump
I II II II II II II II
d. the measure of how bad your workers lift heavy objects
I II II II II II I I II I I b. the pressure on the suction
II II II II II II II II
side of the pump
II II II II
The primary effluent to a B system is
II II mg/ BO . The primary unit removes II I II II II II II II II II II II II II
the secondary unit removes
II II and the final unit removes . What is the BO II II II II II II II II II II II II II
leaving the final unit of the B train
II II II II II II II II
A. II mg/ II
b. II mg/ II
c. II mg/
II
d. I . mg/ II II II II II d. II . mg/ II
The influent to the treatment plant is septic. it is determined that it is coming from a lift
II II II II II II II I II II II II II II II I I II
station upstream from the plant. W hat should the operator
II II I II II II II II I I
A. decrease the lag time for pump operation by moving the floats closer together
I II II II I II II II II II II II II
b. addI adjuster to the influent flow II II II II II II
c. install larger capacity pumps in the lift stations
II II I II II II II II
d. the her nothing you can do to correct this problem A. decrease the lag time for pump
I II II II II II II II II II II II II II II II II II I II
operation by moving the floats closer together
II II II II I II II
W hat is the purpose of amber storage bottles?
II II II II II II I I
A. the color is pretty
II II II I
b. they are cheaper
II II II
c. to protect chemicals that are sensitive to light
I II II II II II II II
d. so you can not see what is inside the container
I II II II II II II II II II II c. to protect chemicals that are
II II II I II II II I
sensitive to light
II I II
alculate S T
II II
Given: SS = mg/ II II II II
Aeration basin volume = , gallons = . II II II I II II II MG
II
WAS concentration = mg/ II II II II
WAS flow rate = . G II II II II II
Exam Questions and answers | Updated
2025 RATED A+
What is the predominant organism in a healthy activated sludge treatment plant?
II II II II II II II II II II II
A. Stalked ciliates
II II
B. rotifersII
C. nematodesII
D. amoebas A. Stalked iliates
II II II II II II II
II A composite sample must be?
II II II II
A. sporadically collected in the treatment plant
II II II II II II
B. taken at one time
II II II II
C. analyzed immediately
II II
D. representative and sub-samples time spaced over
II minutes apart II II II II II II II II II D.
II II II
representative and sub-samples time spaced over
II minutes apart II II II II II II II I
W hat is the standard volume for a BOD sample bottle?
II II II II II II II II II II
A. II II
B. II II
C. II II
D. II II II II II II c. II II
If you have a lime slurry feed line, what is the best valve to use?
II II II II II II I II II II II II II II II
A. plug valve
II II
B. butterfly valve
II II
C. PZ dual check valve
II II II II
D. gate valve A. plug valve
I II II II II II II II
5. If you notice a predominance of rotifers in your activated sludge sample while looking at
II II II II II II I I II II II II II II II II
it under a microscope, what does this indicate
II II II II II II II II
A. healthy sludge
II II
B. young sludge
II II
C. old sludge
II II
D. middle age sludge
II II II II C. old sludge
II II II II II
IIalculate the BO using the given information: II II II II II II
Initial O: . II II
,Final O: . II II
a. II mg/ II
b. II mg/ II
c. II mg/ II
d. I mg/
II II II II II a. II II mg/
If your activated sludge plant begins to nitrify, what conditions would you expect to
II II II II II II I II II II II II II I
decrease
II
A. settling in clarifiers
II II II
B. chlorine demand
II II
C. BO effluent II II
D. TSS in effluent a. settling in the clarifiers
II II II II II II II II II II I
II How do you calibrate a chemical feed pump?
II II II II II I II
A. by measuring the pump output
I II II II II
B. using the SWAG method
II II II II
C. jar test II II
D. with a microscope A. by measuring the pump output
I II II II II II II II II II II II
W hat is the chemical formula for sulfuric acid?
II II II II II II II II
a. O II
b. l II
c. aO II
d. SO II II II II II d. II SO
W hat is the most common type of activated sludge package plants?
II II II II II II II II II II II
a. extended aeration
II II
b. sequential batch reactor
II II II
c. oxidation ditch
II II
d. bardenpho a. extended aeration
II II II II II II I
W hat is the most appropriate method of reducing the F:M ratio?
II II II II I II II II II I II
A. increase wasting
II II
b. decrease wasting
II II
c. reduce BO from influent flow
II II II II II
D. add polymer to AS to increase settling
II II II II II II II II II II II b. decrease wasting
II II
An operator notices a portion of the aeration tank with large bubbles rising up. W hat is the
II I II II I II II I II I II II II II II II II
most likely problem
II II II
, a. equal air distribution
II II II
b. unequal air distribution caused by a blown/clogged diffuser
II II II II II II II II
c. normal operation
II II
d. reason to believe the air filter in the blower is clogged b. unequal air distribution
I I II II II I II II II II II I II II II II II II
caused by a blown diffuser
II II II II II
W hat is suction lift?
II II II I
a. a team approach to lifting heavy objects
I II II II II II II
b. the pressure on the suction side of the pump
I II II II II II II II II
c. the measurement of liquid pressure at the pump
I II II II II II II II
d. the measure of how bad your workers lift heavy objects
I II II II II II I I II I I b. the pressure on the suction
II II II II II II II II
side of the pump
II II II II
The primary effluent to a B system is
II II mg/ BO . The primary unit removes II I II II II II II II II II II II II II
the secondary unit removes
II II and the final unit removes . What is the BO II II II II II II II II II II II II II
leaving the final unit of the B train
II II II II II II II II
A. II mg/ II
b. II mg/ II
c. II mg/
II
d. I . mg/ II II II II II d. II . mg/ II
The influent to the treatment plant is septic. it is determined that it is coming from a lift
II II II II II II II I II II II II II II II I I II
station upstream from the plant. W hat should the operator
II II I II II II II II I I
A. decrease the lag time for pump operation by moving the floats closer together
I II II II I II II II II II II II II
b. addI adjuster to the influent flow II II II II II II
c. install larger capacity pumps in the lift stations
II II I II II II II II
d. the her nothing you can do to correct this problem A. decrease the lag time for pump
I II II II II II II II II II II II II II II II II II I II
operation by moving the floats closer together
II II II II I II II
W hat is the purpose of amber storage bottles?
II II II II II II I I
A. the color is pretty
II II II I
b. they are cheaper
II II II
c. to protect chemicals that are sensitive to light
I II II II II II II II
d. so you can not see what is inside the container
I II II II II II II II II II II c. to protect chemicals that are
II II II I II II II I
sensitive to light
II I II
alculate S T
II II
Given: SS = mg/ II II II II
Aeration basin volume = , gallons = . II II II I II II II MG
II
WAS concentration = mg/ II II II II
WAS flow rate = . G II II II II II
