Minnesota Water Treatment Operator
Class B Exam Practice Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. The primary purpose of coagulation in a drinking water treatment
plant is to:
A. Increase chlorine residual
B. Remove dissolved minerals only
C. Destabilize suspended particles so they can combine
D. Raise water temperature
Correct Answer: C
Coagulation destabilizes small suspended particles and colloids, allowing
them to form larger particles that can be removed during flocculation and
sedimentation.
, 2. Which chemical is commonly used as a coagulant in water treatment?
A. Sodium chloride
B. Alum
C. Calcium carbonate
D. Potassium chloride
Correct Answer: B
Alum is a widely used coagulant that reacts with impurities to form floc
particles that can settle out of water.
3. The purpose of flocculation is to:
A. Kill microorganisms instantly
B. Slowly mix water to build larger floc particles
C. Remove all dissolved solids
D. Add oxygen to water
Correct Answer: B
Flocculation gently mixes coagulated water to encourage small particles to
collide and form larger settleable flocs.
4. Sedimentation removes suspended particles by:
A. Chemical oxidation
B. Gravity settling
,C. Membrane filtration
D. Ultraviolet radiation
Correct Answer: B
Sedimentation allows heavier particles and floc to settle by gravity before
filtration.
5. The main purpose of filtration in drinking water treatment is to:
A. Remove remaining suspended particles and microorganisms
B. Increase hardness
C. Add minerals
D. Remove all chlorine
Correct Answer: A
Filtration provides a barrier that removes remaining particles and helps
reduce microorganisms after sedimentation.
6. Chlorination is primarily used for:
A. Softening water
B. Disinfection
C. Removing color only
D. Increasing alkalinity
Correct Answer: B
, Chlorination disinfects water by destroying or inactivating disease-causing
organisms.
7. The effectiveness of chlorine disinfection depends on:
A. Temperature, pH, and contact time
B. Pipe size only
C. Water color only
D. Pump speed only
Correct Answer: A
Chlorine performance is influenced by factors such as contact time,
temperature, and pH.
8. The term CT in water treatment refers to:
A. Chemical treatment
B. Chlorine concentration multiplied by contact time
C. Chlorine temperature
D. Carbon treatment
Correct Answer: B
CT represents the product of disinfectant concentration and contact time
needed to achieve microbial inactivation.
9. A water treatment operator monitors turbidity because it indicates:
Class B Exam Practice Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. The primary purpose of coagulation in a drinking water treatment
plant is to:
A. Increase chlorine residual
B. Remove dissolved minerals only
C. Destabilize suspended particles so they can combine
D. Raise water temperature
Correct Answer: C
Coagulation destabilizes small suspended particles and colloids, allowing
them to form larger particles that can be removed during flocculation and
sedimentation.
, 2. Which chemical is commonly used as a coagulant in water treatment?
A. Sodium chloride
B. Alum
C. Calcium carbonate
D. Potassium chloride
Correct Answer: B
Alum is a widely used coagulant that reacts with impurities to form floc
particles that can settle out of water.
3. The purpose of flocculation is to:
A. Kill microorganisms instantly
B. Slowly mix water to build larger floc particles
C. Remove all dissolved solids
D. Add oxygen to water
Correct Answer: B
Flocculation gently mixes coagulated water to encourage small particles to
collide and form larger settleable flocs.
4. Sedimentation removes suspended particles by:
A. Chemical oxidation
B. Gravity settling
,C. Membrane filtration
D. Ultraviolet radiation
Correct Answer: B
Sedimentation allows heavier particles and floc to settle by gravity before
filtration.
5. The main purpose of filtration in drinking water treatment is to:
A. Remove remaining suspended particles and microorganisms
B. Increase hardness
C. Add minerals
D. Remove all chlorine
Correct Answer: A
Filtration provides a barrier that removes remaining particles and helps
reduce microorganisms after sedimentation.
6. Chlorination is primarily used for:
A. Softening water
B. Disinfection
C. Removing color only
D. Increasing alkalinity
Correct Answer: B
, Chlorination disinfects water by destroying or inactivating disease-causing
organisms.
7. The effectiveness of chlorine disinfection depends on:
A. Temperature, pH, and contact time
B. Pipe size only
C. Water color only
D. Pump speed only
Correct Answer: A
Chlorine performance is influenced by factors such as contact time,
temperature, and pH.
8. The term CT in water treatment refers to:
A. Chemical treatment
B. Chlorine concentration multiplied by contact time
C. Chlorine temperature
D. Carbon treatment
Correct Answer: B
CT represents the product of disinfectant concentration and contact time
needed to achieve microbial inactivation.
9. A water treatment operator monitors turbidity because it indicates:
