Exam Questions And Correct Answers

South Carolina Physical/Chemical Wastewater Operator Class B Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• Which of the following best describes the purpose of a clarifier in a

wastewater treatment plant?

• To remove dissolved solids
• To aerate the wastewater
• To remove settleable solids
• To disinfect effluent

Rationale: Clarifiers allow suspended solids to settle out of

wastewater through gravity, which is a key step in physical treatment. 1 / 4

• What is the primary chemical used in wastewater treatment for

phosphorus removal?

• Sodium hypochlorite
• Calcium carbonate
• Alum (Aluminum sulfate)
• Ferric chloride

Rationale: Alum reacts with phosphate to form insoluble aluminum

phosphate, which settles out.

3. The term BOD stands for:

• Basic Oxidation Demand
• Biological Oxygen Discharge
• Biochemical Oxygen Demand
• Biological Oxygen Density

Rationale: BOD measures the amount of dissolved oxygen required

by microorganisms to break down organic matter in wastewater.

• Which of the following is a common coagulant used in wastewater

treatment?

• Sodium hydroxide
• Ferric chloride
• Calcium hypochlorite
• Magnesium sulfate

Rationale: Ferric chloride is used to destabilize colloidal particles,

allowing them to aggregate and settle. 2 / 4

• What is the purpose of adding chlorine to wastewater?
• To increase pH
• To disinfect and kill pathogens
• To coagulate solids
• 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:

• Measure pH
• Determine settling characteristics of activated sludge
• Measure chlorine demand
• Determine flow rate

Rationale: SVI indicates how well sludge will settle in secondary

clarifiers, which affects treatment efficiency.

• 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.

• Which of the following is the main purpose of aeration in wastewater

treatment? 3 / 4

• To remove suspended solids
• To supply oxygen to microorganisms for biological treatment
• To remove heavy metals
• To coagulate colloids

Rationale: Aeration provides oxygen required for aerobic

microorganisms to metabolize organic matter.

• What is the typical unit for measuring turbidity in water or

wastewater?

• mg/L

B. NTU

• ppm
• NTU (Nephelometric Turbidity Units)

Rationale: Turbidity is measured using a nephelometer and reported

in NTU.

• Which of the following is a major advantage of chemical

precipitation in wastewater treatment?

• Increases BOD
• Reduces oxygen demand
• Removes dissolved metals and phosphorus
• Improves disinfection

Rationale: Chemical precipitation converts dissolved metals or

phosphates into insoluble forms that can be removed.

• / 4