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

West Virginia Wastewater Class I 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?

• To increase water temperature
• To remove solids, organic matter, and harmful microorganisms
• To generate electricity
• To produce drinking water

Answer: B. To remove solids, organic matter, and harmful microorganisms

Rationale: The main goal of a wastewater treatment plant is to protect

public health and the environment by removing contaminants from sewage. 1 / 4

• What is the typical first step in a conventional wastewater treatment

process?

• Biological treatment
• Primary settling
• Screening
• Disinfection

Answer: C. Screening

Rationale: Screening removes large debris such as sticks, rags, and plastics

to prevent damage to downstream equipment.

• Which unit process is designed to remove settleable solids from

wastewater?

• Aeration
• Primary clarifier
• Filtration
• Disinfection

Answer: B. Primary clarifier

Rationale: Primary clarifiers allow solids to settle by gravity, reducing the

suspended solids load for subsequent treatment.

• What is the main function of an aeration tank in secondary treatment?
• Remove oils and grease
• Promote biological decomposition of organic matter
• Filter out suspended solids
• Kill bacteria 2 / 4

Answer: B. Promote biological decomposition of organic matter

Rationale: Aeration provides oxygen to microorganisms, which break down

organic pollutants in the wastewater.

• What is the typical dissolved oxygen (DO) range for an activated sludge

aeration tank?

• 0.1–0.5 mg/L
• 1–2 mg/L
• 2–4 mg/L
• 4–6 mg/L

Answer: D. 4–6 mg/L

Rationale: Maintaining DO within this range supports effective microbial

activity while avoiding oxygen depletion.

• Which of the following is considered a primary pollutant in wastewater?
• Nitrate
• Phosphate
• Fecal coliform bacteria
• Suspended solids

Answer: D. Suspended solids

Rationale: Suspended solids are considered primary pollutants because

they are directly introduced into wastewater and can be removed by primary treatment. 3 / 4

• What is the primary purpose of chlorination in wastewater treatment?
• Remove suspended solids
• Kill pathogenic microorganisms
• Reduce turbidity
• Oxidize ammonia

Answer: B. Kill pathogenic microorganisms

Rationale: Chlorine is used as a disinfectant to protect public health by

destroying harmful bacteria and viruses.

• Which of the following is an indicator organism for fecal contamination?
• Pseudomonas
• Coliform bacteria
• Streptomyces
• Clostridium

Answer: B. Coliform bacteria

Rationale: Coliform bacteria, particularly Escherichia coli, indicate

potential presence of pathogens in water or wastewater.

• What is the main purpose of a grit chamber in wastewater treatment?
• Remove biodegradable solids
• Remove heavy inorganic solids like sand and gravel
• Remove oils and grease
• Promote microbial growth
• / 4