West Virginia Wastewater Class III Operator Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

West Virginia Wastewater Class III Operator Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• Which of the following is the primary purpose of a wastewater

treatment plant?

• Produce potable water
• Reduce solids only
• Protect public health and the environment by treating wastewater
• Generate electricity

Rationale: The main goal of wastewater treatment is to remove pollutants

to prevent harm to humans and the environment.

2. BOD stands for: 1 / 4

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

Rationale: BOD measures the amount of oxygen required by

microorganisms to decompose organic matter in water.

• Which microorganism is primarily responsible for breaking down organic

matter in the activated sludge process?

• Algae
• Protozoa
• Bacteria
• Fungi

Rationale: Bacteria are the main decomposers in activated sludge,

consuming organic material and reducing BOD.

• What is the primary function of a clarifier in wastewater treatment?
• Aerate water
• Separate solids from liquids
• Disinfect water
• Add chemicals

Rationale: Clarifiers allow solids to settle so clarified water can move to

the next treatment stage.

• The term “sludge age” in an activated sludge process refers to: 2 / 4

• The age of the sludge tank
• The average time solids remain in the system
• The age of the operator
• The time sludge spends in the dewatering process

Rationale: Sludge age (or mean cell residence time) affects microbial

growth and process efficiency.

6. Nitrification in wastewater treatment converts:

• Nitrogen gas to nitrate
• Ammonia to nitrate
• Nitrate to ammonia
• Nitrite to phosphorus

Rationale: Nitrifying bacteria convert ammonia (NH₃) first to nitrite (NO₂⁻) and then to nitrate (NO₃⁻).

7. Denitrification is a process that converts:

• Nitrate to ammonia
• Nitrate to nitrogen gas
• Ammonia to nitrate
• Nitrite to phosphorus

Rationale: Denitrification removes nitrogen from wastewater by

converting nitrate to nitrogen gas, reducing eutrophication potential.

• Phosphorus removal in wastewater is typically achieved by: 3 / 4

• Biological filtration only
• Chemical precipitation or enhanced biological processes
• Aeration only
• Screening

Rationale: Phosphorus can be removed chemically using alum, ferric

chloride, or biologically in enhanced phosphorus removal systems.

9. The purpose of aeration in wastewater treatment is to:

• Cool water
• Remove solids
• Supply oxygen to microorganisms
• Reduce pH

Rationale: Aeration provides oxygen for bacteria to degrade organic

matter.

• A typical MLSS (Mixed Liquor Suspended Solids) concentration in an

activated sludge system is:

• 10–50 mg/L
• 100–200 mg/L
• 2000–4000 mg/L
• 10,000–20,000 mg/L

Rationale: MLSS is usually maintained between 2000–4000 mg/L to

optimize treatment efficiency.

11. Sludge volume index (SVI) measures:

• / 4