Page 1 of 48
BASIC WASTEWATER OPERATOR PRACTICE EXAM
NEWEST 2026 ACTUAL EXAM QUESTIONS AND CORRECT
DETAILED ANSWERS (VERIFIED ANSWERS) ALL
ANSWERED {125 Q & A} ALREADY GRADED A+ | BRAND
NEW! | 100% GUARANTEED 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
,Page 2 of 48
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
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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?
, Page 4 of 48
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?
BASIC WASTEWATER OPERATOR PRACTICE EXAM
NEWEST 2026 ACTUAL EXAM QUESTIONS AND CORRECT
DETAILED ANSWERS (VERIFIED ANSWERS) ALL
ANSWERED {125 Q & A} ALREADY GRADED A+ | BRAND
NEW! | 100% GUARANTEED 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
,Page 2 of 48
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
,Page 3 of 48
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?
, Page 4 of 48
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?
