South Carolina Physical/Chemical
Wastewater Operator Class B Practice
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which of the following best describes the purpose of a clarifier in a
wastewater treatment plant?
A. To remove dissolved solids
B. To aerate the wastewater
C. To remove settleable solids
D. To disinfect effluent
Rationale: Clarifiers allow suspended solids to settle out of
wastewater through gravity, which is a key step in physical
treatment.
,2. What is the primary chemical used in wastewater treatment for
phosphorus removal?
A. Sodium hypochlorite
B. Calcium carbonate
C. Alum (Aluminum sulfate)
D. Ferric chloride
Rationale: Alum reacts with phosphate to form insoluble aluminum
phosphate, which settles out.
3. The term BOD stands for:
A. Basic Oxidation Demand
B. Biological Oxygen Discharge
C. Biochemical Oxygen Demand
D. Biological Oxygen Density
Rationale: BOD measures the amount of dissolved oxygen required
by microorganisms to break down organic matter in wastewater.
4. Which of the following is a common coagulant used in wastewater
treatment?
A. Sodium hydroxide
B. Ferric chloride
C. Calcium hypochlorite
D. Magnesium sulfate
Rationale: Ferric chloride is used to destabilize colloidal particles,
allowing them to aggregate and settle.
,5. What is the purpose of adding chlorine to wastewater?
A. To increase pH
B. To disinfect and kill pathogens
C. To coagulate solids
D. To remove BOD
Rationale: Chlorination is a chemical process used to disinfect
wastewater and reduce the risk of disease.
6. Sludge volume index (SVI) is used to:
A. Measure pH
B. Determine settling characteristics of activated sludge
C. Measure chlorine demand
D. Determine flow rate
Rationale: SVI indicates how well sludge will settle in secondary
clarifiers, which affects treatment efficiency.
7. What is the typical pH range for biological treatment processes?
A. 2.0–3.0
B. 5.0–6.0
C. 6.5–8.5
D. 9.0–10.0
Rationale: Most microorganisms in biological treatment thrive in a
near-neutral pH range.
8. Which of the following is the main purpose of aeration in wastewater
treatment?
, A. To remove suspended solids
B. To supply oxygen to microorganisms for biological treatment
C. To remove heavy metals
D. To coagulate colloids
Rationale: Aeration provides oxygen required for aerobic
microorganisms to metabolize organic matter.
9. What is the typical unit for measuring turbidity in water or
wastewater?
A. mg/L
B. NTU
C. ppm
D. NTU (Nephelometric Turbidity Units)
Rationale: Turbidity is measured using a nephelometer and reported
in NTU.
10. Which of the following is a major advantage of chemical
precipitation in wastewater treatment?
A. Increases BOD
B. Reduces oxygen demand
C. Removes dissolved metals and phosphorus
D. Improves disinfection
Rationale: Chemical precipitation converts dissolved metals or
phosphates into insoluble forms that can be removed.
Wastewater Operator Class B Practice
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which of the following best describes the purpose of a clarifier in a
wastewater treatment plant?
A. To remove dissolved solids
B. To aerate the wastewater
C. To remove settleable solids
D. To disinfect effluent
Rationale: Clarifiers allow suspended solids to settle out of
wastewater through gravity, which is a key step in physical
treatment.
,2. What is the primary chemical used in wastewater treatment for
phosphorus removal?
A. Sodium hypochlorite
B. Calcium carbonate
C. Alum (Aluminum sulfate)
D. Ferric chloride
Rationale: Alum reacts with phosphate to form insoluble aluminum
phosphate, which settles out.
3. The term BOD stands for:
A. Basic Oxidation Demand
B. Biological Oxygen Discharge
C. Biochemical Oxygen Demand
D. Biological Oxygen Density
Rationale: BOD measures the amount of dissolved oxygen required
by microorganisms to break down organic matter in wastewater.
4. Which of the following is a common coagulant used in wastewater
treatment?
A. Sodium hydroxide
B. Ferric chloride
C. Calcium hypochlorite
D. Magnesium sulfate
Rationale: Ferric chloride is used to destabilize colloidal particles,
allowing them to aggregate and settle.
,5. What is the purpose of adding chlorine to wastewater?
A. To increase pH
B. To disinfect and kill pathogens
C. To coagulate solids
D. To remove BOD
Rationale: Chlorination is a chemical process used to disinfect
wastewater and reduce the risk of disease.
6. Sludge volume index (SVI) is used to:
A. Measure pH
B. Determine settling characteristics of activated sludge
C. Measure chlorine demand
D. Determine flow rate
Rationale: SVI indicates how well sludge will settle in secondary
clarifiers, which affects treatment efficiency.
7. What is the typical pH range for biological treatment processes?
A. 2.0–3.0
B. 5.0–6.0
C. 6.5–8.5
D. 9.0–10.0
Rationale: Most microorganisms in biological treatment thrive in a
near-neutral pH range.
8. Which of the following is the main purpose of aeration in wastewater
treatment?
, A. To remove suspended solids
B. To supply oxygen to microorganisms for biological treatment
C. To remove heavy metals
D. To coagulate colloids
Rationale: Aeration provides oxygen required for aerobic
microorganisms to metabolize organic matter.
9. What is the typical unit for measuring turbidity in water or
wastewater?
A. mg/L
B. NTU
C. ppm
D. NTU (Nephelometric Turbidity Units)
Rationale: Turbidity is measured using a nephelometer and reported
in NTU.
10. Which of the following is a major advantage of chemical
precipitation in wastewater treatment?
A. Increases BOD
B. Reduces oxygen demand
C. Removes dissolved metals and phosphorus
D. Improves disinfection
Rationale: Chemical precipitation converts dissolved metals or
phosphates into insoluble forms that can be removed.
