Minnesota Water Quality Engineering
Certification Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
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1. Which parameter is primarily used to indicate the oxygen demand of
biodegradable organic matter in water?
A. Total Dissolved Solids (TDS)
B. Biochemical Oxygen Demand (BOD)
C. Turbidity
D. Alkalinity
Correct Answer: B
BOD measures the amount of dissolved oxygen required by
microorganisms to decompose organic matter in water, making it a
key indicator of organic pollution.
2. Which process is most commonly used for pathogen removal in
drinking water treatment?
, A. Coagulation
B. Sedimentation
C. Disinfection
D. Flocculation
Correct Answer: C
Disinfection, commonly using chlorine or UV light, is designed to
inactivate or destroy pathogenic microorganisms in water.
3. What is the primary purpose of coagulation in water treatment?
A. Remove dissolved salts
B. Neutralize pH
C. Destabilize suspended particles
D. Increase oxygen content
Correct Answer: C
Coagulation neutralizes charges on suspended particles, allowing
them to aggregate into larger flocs for easier removal.
4. Which unit process follows coagulation in conventional water
treatment?
A. Sedimentation
B. Aeration
C. Filtration
D. Chlorination
Correct Answer: C
, Filtration follows sedimentation and removes remaining fine
particles from water using granular media.
5. What does turbidity measure in water?
A. Hardness
B. Clarity caused by suspended particles
C. Dissolved oxygen
D. Salinity
Correct Answer: B
Turbidity measures the cloudiness of water caused by suspended
particles such as silt, algae, and organic matter.
6. Which chemical is most commonly used for primary disinfection in
municipal water systems?
A. Sulfur dioxide
B. Chlorine
C. Sodium bicarbonate
D. Alum
Correct Answer: B
Chlorine is widely used due to its effectiveness and residual
disinfection capability.
7. What is the main purpose of sedimentation in water treatment?
A. Destroy bacteria
B. Remove dissolved solids
C. Settle suspended solids by gravity
, D. Increase alkalinity
Correct Answer: C
Sedimentation allows heavier particles to settle out of water under
the influence of gravity.
8. Which parameter indicates acidity or alkalinity of water?
A. Hardness
B. pH
C. Turbidity
D. Conductivity
Correct Answer: B
pH measures hydrogen ion concentration, indicating how acidic or
basic water is.
9. What is the main function of activated carbon in water treatment?
A. Remove pathogens
B. Remove organic compounds and odors
C. Increase hardness
D. Add oxygen
Correct Answer: B
Activated carbon adsorbs organic compounds, improving taste, odor,
and chemical quality.
10. Which process is used to remove dissolved salts from water?
A. Coagulation
B. Reverse osmosis
Certification Exam Practice Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
Download Pdf
1. Which parameter is primarily used to indicate the oxygen demand of
biodegradable organic matter in water?
A. Total Dissolved Solids (TDS)
B. Biochemical Oxygen Demand (BOD)
C. Turbidity
D. Alkalinity
Correct Answer: B
BOD measures the amount of dissolved oxygen required by
microorganisms to decompose organic matter in water, making it a
key indicator of organic pollution.
2. Which process is most commonly used for pathogen removal in
drinking water treatment?
, A. Coagulation
B. Sedimentation
C. Disinfection
D. Flocculation
Correct Answer: C
Disinfection, commonly using chlorine or UV light, is designed to
inactivate or destroy pathogenic microorganisms in water.
3. What is the primary purpose of coagulation in water treatment?
A. Remove dissolved salts
B. Neutralize pH
C. Destabilize suspended particles
D. Increase oxygen content
Correct Answer: C
Coagulation neutralizes charges on suspended particles, allowing
them to aggregate into larger flocs for easier removal.
4. Which unit process follows coagulation in conventional water
treatment?
A. Sedimentation
B. Aeration
C. Filtration
D. Chlorination
Correct Answer: C
, Filtration follows sedimentation and removes remaining fine
particles from water using granular media.
5. What does turbidity measure in water?
A. Hardness
B. Clarity caused by suspended particles
C. Dissolved oxygen
D. Salinity
Correct Answer: B
Turbidity measures the cloudiness of water caused by suspended
particles such as silt, algae, and organic matter.
6. Which chemical is most commonly used for primary disinfection in
municipal water systems?
A. Sulfur dioxide
B. Chlorine
C. Sodium bicarbonate
D. Alum
Correct Answer: B
Chlorine is widely used due to its effectiveness and residual
disinfection capability.
7. What is the main purpose of sedimentation in water treatment?
A. Destroy bacteria
B. Remove dissolved solids
C. Settle suspended solids by gravity
, D. Increase alkalinity
Correct Answer: C
Sedimentation allows heavier particles to settle out of water under
the influence of gravity.
8. Which parameter indicates acidity or alkalinity of water?
A. Hardness
B. pH
C. Turbidity
D. Conductivity
Correct Answer: B
pH measures hydrogen ion concentration, indicating how acidic or
basic water is.
9. What is the main function of activated carbon in water treatment?
A. Remove pathogens
B. Remove organic compounds and odors
C. Increase hardness
D. Add oxygen
Correct Answer: B
Activated carbon adsorbs organic compounds, improving taste, odor,
and chemical quality.
10. Which process is used to remove dissolved salts from water?
A. Coagulation
B. Reverse osmosis
