Level 3 Practice Exam Questions And

Nunavut Wastewater Treatment Operator Level 3 Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• Which of the following best describes the primary purpose of a

wastewater treatment plant?

• To produce drinking water
• To remove contaminants from wastewater to protect human

health and the environment

• To increase the flow of wastewater to rivers
• To generate energy from sewage

Rationale: The main goal of wastewater treatment is to remove

pollutants to prevent harm to humans and the environment.

• Which process is considered a primary treatment in wastewater

treatment? 1 / 4

• Biological nutrient removal
• Sedimentation in a primary clarifier
• Disinfection with chlorine
• Advanced filtration

Rationale: Primary treatment involves physical processes like settling

to remove suspended solids.

3. The purpose of secondary treatment is primarily to:

• Remove heavy metals
• Remove dissolved organic matter using biological processes
• Sterilize the effluent
• Settle grit and sand

Rationale: Secondary treatment relies on microbial activity to

degrade dissolved organic materials.

• In a conventional activated sludge process, what is the function of the

aeration tank?

• Sediment solids
• Remove grit
• Provide oxygen for microorganisms to break down organic matter
• Filter effluent

Rationale: Aeration supplies oxygen for bacteria to metabolize

organic pollutants.

• Which of the following is a common indicator of wastewater strength?
• pH 2 / 4

• Biochemical Oxygen Demand (BOD)
• Color
• Temperature

Rationale: BOD measures the amount of oxygen needed by microbes

to decompose organic matter, indicating wastewater strength.

• What is the typical retention time for primary clarifiers?
• 10–20 minutes
• 1–2 hours
• 6–8 hours
• 24 hours

Rationale: Primary clarifiers usually retain wastewater for 1–2 hours

to allow solids to settle.

7. Sludge thickening primarily serves to:

• Remove pathogens
• Increase aeration efficiency
• Reduce water content of sludge before digestion
• Neutralize pH

Rationale: Thickening reduces sludge volume by removing water,

making subsequent treatment more efficient.

• Which of the following is an example of a tertiary treatment method?
• Primary sedimentation
• Trickling filter
• Filtration and nutrient removal 3 / 4

• Activated sludge aeration

Rationale: Tertiary treatment includes advanced processes like

nutrient removal, filtration, and polishing of effluent.

9. Nitrification in wastewater treatment converts:

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

Rationale: Nitrifying bacteria oxidize ammonia to nitrite and then to

nitrate.

10. Denitrification is important because it:

• Produces ammonia
• Converts nitrate to nitrite
• Converts nitrate to nitrogen gas, removing nitrogen from

wastewater

• Adds oxygen to effluent

Rationale: Denitrification reduces nitrate to nitrogen gas, preventing

eutrophication in receiving waters.

11. The main hazard in a wastewater plant is typically:

• Electrical shock only
• Exposure to pathogens and toxic gases
• UV light
• Excessive sunlight
• / 4