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1. What is the primary purpose of coagulation in water treatment?
a. To disinfect water
b. To remove dissolved minerals
c. To destabilize and aggregate suspended particles
d. To soften water
Coagulation helps small particles clump together so they can be removed in
sedimentation and filtration.
2. Which chemical is commonly used as a coagulant in
water treatment?
a. Chlorine
b. Aluminum sulfate (alum)
c. Fluoride
d. Sodium hydroxide
Alum is widely used because it efficiently binds with suspended particles.
3. The pH of water affects which treatment process the most?
a. Filtration
b. Coagulation and disinfection
c. Aeration
d. Sludge dewatering
Nebraska
2026 Q&AWater Treatment
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,Nebraska
2026 Q&AWater Treatment
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The effectiveness of coagulants and disinfectants depends on the water’s pH.
4. What is the primary purpose of sedimentation in water
treatment?
a. To kill bacteria
b. To add minerals
c. To allow heavy particles to settle out of water
d. To adjust pH
Sedimentation removes solids by gravity before filtration.
5. Which process uses sand or multimedia to remove suspended
particles?
a. Coagulation
b. Filtration
c. Chlorination
d. Softening
Filters physically trap particles that remain after coagulation and
sedimentation.
6. What is the main purpose of disinfection in water treatment?
a. To remove turbidity
b. To kill or inactivate pathogenic organisms
c. To remove dissolved solids
d. To adjust pH
Disinfection ensures water is microbiologically safe for consumption.
7. Which disinfectant is most commonly used in public
water systems?
a. Ozone
Nebraska
2026 Q&AWater Treatment
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, Nebraska
2026 Q&AWater Treatment
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b. Chlorine dioxide
c. Chlorine
d. Ultraviolet light
Chlorine is effective, economical, and provides residual protection in the
distribution system.
8. What is the ideal range for free chlorine residual in a
distribution system?
a. 0–0.1 mg/L
b. 0.2–0.5 mg/L
c. 0.5–2.0 mg/L
d. 2–5 mg/L
Maintaining this range ensures effective disinfection without creating
taste and odor issues.
9. Which water quality parameter measures the clarity of water?
a. pH
b. Conductivity
c. Turbidity
d. Hardness
Turbidity indicates the amount of suspended particles in water.
10. What is a common unit for measuring turbidity?
a. mg/L
b. pH units
c. Nephelometric Turbidity Units (NTU)
d. ppm
NTU is standard for expressing water clarity.
11. What is the primary purpose of aeration in water treatment?
a. To remove chlorine
Nebraska
2026 Q&AWater Treatment
| Instant Operator
Download Pdf Level I Exam Questions And Correct Answers (Verified Answers) Plus Rationales
2026 Q&AWater Treatment
| Instant Operator
Download Pdf Level I Exam Questions And Correct Answers (Verified Answers) Plus Rationales
1. What is the primary purpose of coagulation in water treatment?
a. To disinfect water
b. To remove dissolved minerals
c. To destabilize and aggregate suspended particles
d. To soften water
Coagulation helps small particles clump together so they can be removed in
sedimentation and filtration.
2. Which chemical is commonly used as a coagulant in
water treatment?
a. Chlorine
b. Aluminum sulfate (alum)
c. Fluoride
d. Sodium hydroxide
Alum is widely used because it efficiently binds with suspended particles.
3. The pH of water affects which treatment process the most?
a. Filtration
b. Coagulation and disinfection
c. Aeration
d. Sludge dewatering
Nebraska
2026 Q&AWater Treatment
| Instant Operator
Download Pdf Level I Exam Questions And Correct Answers (Verified Answers) Plus Rationales
,Nebraska
2026 Q&AWater Treatment
| Instant Operator
Download Pdf Level I Exam Questions And Correct Answers (Verified Answers) Plus Rationales
The effectiveness of coagulants and disinfectants depends on the water’s pH.
4. What is the primary purpose of sedimentation in water
treatment?
a. To kill bacteria
b. To add minerals
c. To allow heavy particles to settle out of water
d. To adjust pH
Sedimentation removes solids by gravity before filtration.
5. Which process uses sand or multimedia to remove suspended
particles?
a. Coagulation
b. Filtration
c. Chlorination
d. Softening
Filters physically trap particles that remain after coagulation and
sedimentation.
6. What is the main purpose of disinfection in water treatment?
a. To remove turbidity
b. To kill or inactivate pathogenic organisms
c. To remove dissolved solids
d. To adjust pH
Disinfection ensures water is microbiologically safe for consumption.
7. Which disinfectant is most commonly used in public
water systems?
a. Ozone
Nebraska
2026 Q&AWater Treatment
| Instant Operator
Download Pdf Level I Exam Questions And Correct Answers (Verified Answers) Plus Rationales
, Nebraska
2026 Q&AWater Treatment
| Instant Operator
Download Pdf Level I Exam Questions And Correct Answers (Verified Answers) Plus Rationales
b. Chlorine dioxide
c. Chlorine
d. Ultraviolet light
Chlorine is effective, economical, and provides residual protection in the
distribution system.
8. What is the ideal range for free chlorine residual in a
distribution system?
a. 0–0.1 mg/L
b. 0.2–0.5 mg/L
c. 0.5–2.0 mg/L
d. 2–5 mg/L
Maintaining this range ensures effective disinfection without creating
taste and odor issues.
9. Which water quality parameter measures the clarity of water?
a. pH
b. Conductivity
c. Turbidity
d. Hardness
Turbidity indicates the amount of suspended particles in water.
10. What is a common unit for measuring turbidity?
a. mg/L
b. pH units
c. Nephelometric Turbidity Units (NTU)
d. ppm
NTU is standard for expressing water clarity.
11. What is the primary purpose of aeration in water treatment?
a. To remove chlorine
Nebraska
2026 Q&AWater Treatment
| Instant Operator
Download Pdf Level I Exam Questions And Correct Answers (Verified Answers) Plus Rationales
