Water Treatment Operator Class C Licensing
Exam Questions With Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
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1. Which of the following is the primary purpose of coagulation in
water treatment?
A. To kill bacteria
B. To remove dissolved gases
C. To destabilize and aggregate suspended particles
D. To adjust pH
Coagulation is the process of adding chemicals (coagulants) to
water to neutralize particle charges, allowing them to aggregate
into larger flocs for easier removal in sedimentation and
filtration.
2. What is the most commonly used coagulant in water treatment
plants?
A. Sodium hydroxide
B. Aluminum sulfate (alum)
, C. Calcium carbonate
D. Chlorine dioxide
Aluminum sulfate, or alum, is widely used because it effectively
destabilizes particles and forms flocs that can be removed in
subsequent treatment steps.
3. What is the main function of flocculation?
A. Disinfection
B. pH adjustment
C. To gently mix water to encourage floc formation
D. Softening water
Flocculation follows coagulation and involves slow, gentle mixing
to promote the collision and aggregation of destabilized particles
into larger, settleable flocs.
4. Which water treatment process is primarily used to remove
hardness caused by calcium and magnesium?
A. Filtration
B. Ion exchange (water softening)
C. Coagulation
D. Sedimentation
Ion exchange replaces calcium and magnesium ions with sodium
or potassium ions, reducing water hardness.
,5. What is the purpose of sedimentation in water treatment?
A. To disinfect water
B. To remove settleable solids by gravity
C. To soften water
D. To adjust pH
Sedimentation allows heavier particles to settle at the bottom of
a tank, reducing turbidity before filtration.
6. What type of filter media is most commonly used in slow sand
filtration?
A. Gravel
B. Activated carbon
C. Sand
D. Anthracite
Slow sand filters rely on sand as the primary medium, which
traps particles and provides biological treatment through the
schmutzdecke layer.
7. What is the primary purpose of chlorination in water treatment?
A. To remove hardness
B. To disinfect water and kill pathogens
C. To remove turbidity
D. To promote flocculation
, Chlorination introduces chlorine to kill bacteria, viruses, and
other pathogens, ensuring safe drinking water.
8. Which of the following is a byproduct of chlorination?
A. Sodium hydroxide
B. Trihalomethanes (THMs)
C. Calcium carbonate
D. Ozone
Chlorine reacts with natural organic matter in water to form
disinfection byproducts like trihalomethanes, which are
regulated due to health concerns.
9. What is the primary goal of pH adjustment in water treatment?
A. To optimize coagulation and corrosion control
B. To disinfect water
C. To remove suspended solids
D. To remove dissolved gases
Proper pH ensures effective coagulation, prevents pipe corrosion,
and enhances chemical treatment efficiency.
10. Which of the following is a common method for removing
iron from water?
A. Chlorination followed by filtration
B. Oxidation followed by filtration
Exam Questions With Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. Which of the following is the primary purpose of coagulation in
water treatment?
A. To kill bacteria
B. To remove dissolved gases
C. To destabilize and aggregate suspended particles
D. To adjust pH
Coagulation is the process of adding chemicals (coagulants) to
water to neutralize particle charges, allowing them to aggregate
into larger flocs for easier removal in sedimentation and
filtration.
2. What is the most commonly used coagulant in water treatment
plants?
A. Sodium hydroxide
B. Aluminum sulfate (alum)
, C. Calcium carbonate
D. Chlorine dioxide
Aluminum sulfate, or alum, is widely used because it effectively
destabilizes particles and forms flocs that can be removed in
subsequent treatment steps.
3. What is the main function of flocculation?
A. Disinfection
B. pH adjustment
C. To gently mix water to encourage floc formation
D. Softening water
Flocculation follows coagulation and involves slow, gentle mixing
to promote the collision and aggregation of destabilized particles
into larger, settleable flocs.
4. Which water treatment process is primarily used to remove
hardness caused by calcium and magnesium?
A. Filtration
B. Ion exchange (water softening)
C. Coagulation
D. Sedimentation
Ion exchange replaces calcium and magnesium ions with sodium
or potassium ions, reducing water hardness.
,5. What is the purpose of sedimentation in water treatment?
A. To disinfect water
B. To remove settleable solids by gravity
C. To soften water
D. To adjust pH
Sedimentation allows heavier particles to settle at the bottom of
a tank, reducing turbidity before filtration.
6. What type of filter media is most commonly used in slow sand
filtration?
A. Gravel
B. Activated carbon
C. Sand
D. Anthracite
Slow sand filters rely on sand as the primary medium, which
traps particles and provides biological treatment through the
schmutzdecke layer.
7. What is the primary purpose of chlorination in water treatment?
A. To remove hardness
B. To disinfect water and kill pathogens
C. To remove turbidity
D. To promote flocculation
, Chlorination introduces chlorine to kill bacteria, viruses, and
other pathogens, ensuring safe drinking water.
8. Which of the following is a byproduct of chlorination?
A. Sodium hydroxide
B. Trihalomethanes (THMs)
C. Calcium carbonate
D. Ozone
Chlorine reacts with natural organic matter in water to form
disinfection byproducts like trihalomethanes, which are
regulated due to health concerns.
9. What is the primary goal of pH adjustment in water treatment?
A. To optimize coagulation and corrosion control
B. To disinfect water
C. To remove suspended solids
D. To remove dissolved gases
Proper pH ensures effective coagulation, prevents pipe corrosion,
and enhances chemical treatment efficiency.
10. Which of the following is a common method for removing
iron from water?
A. Chlorination followed by filtration
B. Oxidation followed by filtration
