Basic Wastewater Operator Practice Exam
(2026/2027) Questions and Verified Answers, 100%
Guarantee Pass
What is the predominant organism in a healthy activated sludge treatment plant?
A. Stalked ciliates
B. rotifers
C. nematodes
D. amoebas - CORRECT ANSWER -A. Stalked Ciliates
A composite sample must be?
A. sporadically collected in the treatment plant
B. taken at one time
C. analyzed immediately
D. representative and sub-samples time spaced over 15 minutes apart - CORRECT
ANSWER -D. representative and sub-samples time spaced over 15 minutes apart
What is the standard volume for a BOD sample bottle?
A. 150 mL
B. 200 mL
C. 300 mL
D. 500 mL - CORRECT ANSWER -c. 300 mL
,If you have a lime slurry feed line, what is the best valve to use?
A. plug valve
B. butterfly valve
C. RPZ dual check valve
D. gate valve - CORRECT ANSWER -A. plug valve
5. If you notice a predominance of rotifers in your activated sludge sample while
looking at it under a microscope, what does this indicate?
A. healthy sludge
B. young sludge
C. old sludge
D. middle age sludge - CORRECT ANSWER -C. old sludge
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 - CORRECT 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 - CORRECT 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 - CORRECT ANSWER -A. by measuring the pump output
What is the chemical formula for sulfuric acid?
a. HNO3
b. HCl
c. NaOH
d. H2SO4 - CORRECT 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 - CORRECT 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 - CORRECT 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 - CORRECT ANSWER -
b. unequal air distribution caused by a blown diffuser
What is suction lift?
a. a team approach to lifting heavy objects
(2026/2027) Questions and Verified Answers, 100%
Guarantee Pass
What is the predominant organism in a healthy activated sludge treatment plant?
A. Stalked ciliates
B. rotifers
C. nematodes
D. amoebas - CORRECT ANSWER -A. Stalked Ciliates
A composite sample must be?
A. sporadically collected in the treatment plant
B. taken at one time
C. analyzed immediately
D. representative and sub-samples time spaced over 15 minutes apart - CORRECT
ANSWER -D. representative and sub-samples time spaced over 15 minutes apart
What is the standard volume for a BOD sample bottle?
A. 150 mL
B. 200 mL
C. 300 mL
D. 500 mL - CORRECT ANSWER -c. 300 mL
,If you have a lime slurry feed line, what is the best valve to use?
A. plug valve
B. butterfly valve
C. RPZ dual check valve
D. gate valve - CORRECT ANSWER -A. plug valve
5. If you notice a predominance of rotifers in your activated sludge sample while
looking at it under a microscope, what does this indicate?
A. healthy sludge
B. young sludge
C. old sludge
D. middle age sludge - CORRECT ANSWER -C. old sludge
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 - CORRECT 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 - CORRECT 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 - CORRECT ANSWER -A. by measuring the pump output
What is the chemical formula for sulfuric acid?
a. HNO3
b. HCl
c. NaOH
d. H2SO4 - CORRECT 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 - CORRECT 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 - CORRECT 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 - CORRECT ANSWER -
b. unequal air distribution caused by a blown diffuser
What is suction lift?
a. a team approach to lifting heavy objects
