Water Treatment Operator Class A Licensing Exam
Questions and Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of coagulation in water treatment?
A. To disinfect pathogens
B. To remove dissolved salts
C. To destabilize suspended particles
D. To adjust pH
Answer: C
Coagulation neutralizes the charges of suspended particles so they can
clump together for easier removal.
2. Which chemical is most commonly used as a coagulant?
A. Sodium chloride
B. Alum (aluminum sulfate)
C. Calcium carbonate
D. Chlorine
,Answer: B
Alum is widely used to form flocs by destabilizing suspended solids.
3. What is flocculation?
A. Rapid mixing of chemicals
B. Slow mixing to form larger particles
C. Chlorine disinfection
D. Sediment removal by filtration
Answer: B
Flocculation gently mixes water to encourage particle aggregation into
larger flocs.
4. What is the main purpose of sedimentation?
A. Dissolve minerals
B. Remove floating oils
C. Allow solids to settle by gravity
D. Increase chlorine contact time
Answer: C
Sedimentation relies on gravity to settle suspended solids out of water.
,5. Which process follows sedimentation in conventional treatment?
A. Aeration
B. Filtration
C. Fluoridation
D. Storage
Answer: B
Filtration removes remaining fine particles after sedimentation.
6. What is the typical disinfectant used in municipal water systems?
A. Ozone
B. Chlorine
C. Potassium permanganate
D. Hydrogen peroxide
Answer: B
Chlorine is widely used due to effectiveness and residual protection.
7. What is turbidity a measure of?
, A. pH level
B. Water hardness
C. Cloudiness caused by particles
D. Chlorine concentration
Answer: C
Turbidity indicates suspended particles that reduce water clarity.
8. What unit is turbidity measured in?
A. ppm
B. NTU
C. mg/L
D. psi
Answer: B
NTU (Nephelometric Turbidity Units) measure water cloudiness.
9. What is the purpose of a rapid mix tank?
A. Sediment settling
B. Chemical dispersion
C. Water storage
D. Chlorine removal
Questions and Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant Download Pdf
1. What is the primary purpose of coagulation in water treatment?
A. To disinfect pathogens
B. To remove dissolved salts
C. To destabilize suspended particles
D. To adjust pH
Answer: C
Coagulation neutralizes the charges of suspended particles so they can
clump together for easier removal.
2. Which chemical is most commonly used as a coagulant?
A. Sodium chloride
B. Alum (aluminum sulfate)
C. Calcium carbonate
D. Chlorine
,Answer: B
Alum is widely used to form flocs by destabilizing suspended solids.
3. What is flocculation?
A. Rapid mixing of chemicals
B. Slow mixing to form larger particles
C. Chlorine disinfection
D. Sediment removal by filtration
Answer: B
Flocculation gently mixes water to encourage particle aggregation into
larger flocs.
4. What is the main purpose of sedimentation?
A. Dissolve minerals
B. Remove floating oils
C. Allow solids to settle by gravity
D. Increase chlorine contact time
Answer: C
Sedimentation relies on gravity to settle suspended solids out of water.
,5. Which process follows sedimentation in conventional treatment?
A. Aeration
B. Filtration
C. Fluoridation
D. Storage
Answer: B
Filtration removes remaining fine particles after sedimentation.
6. What is the typical disinfectant used in municipal water systems?
A. Ozone
B. Chlorine
C. Potassium permanganate
D. Hydrogen peroxide
Answer: B
Chlorine is widely used due to effectiveness and residual protection.
7. What is turbidity a measure of?
, A. pH level
B. Water hardness
C. Cloudiness caused by particles
D. Chlorine concentration
Answer: C
Turbidity indicates suspended particles that reduce water clarity.
8. What unit is turbidity measured in?
A. ppm
B. NTU
C. mg/L
D. psi
Answer: B
NTU (Nephelometric Turbidity Units) measure water cloudiness.
9. What is the purpose of a rapid mix tank?
A. Sediment settling
B. Chemical dispersion
C. Water storage
D. Chlorine removal
