Exam Questions And Correct Answers

Northwest Territories Wastewater Treatment Operator Level 2 Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• Which of the following is the primary purpose of wastewater

treatment?

• Increase water temperature
• Remove nutrients and pathogens
• Reduce water color
• Produce electricity
• Remove nutrients and pathogens

Rationale: The primary purpose of wastewater treatment is to

protect public health and the environment by removing harmful pathogens, organic matter, and excess nutrients from wastewater. 1 / 4

• What is the typical range of pH for effluent discharged from a

municipal wastewater treatment plant?

A. 3–5

B. 5–6

C. 6–9

D. 9–11

Rationale: Effluent pH is typically maintained between 6 and 9 to

prevent harm to aquatic life and comply with regulatory standards.

• Which microorganism group is primarily responsible for the biological

treatment of wastewater in an activated sludge system?

• Algae
• Protozoa
• Bacteria
• Viruses

Rationale: Bacteria break down organic matter in the wastewater

through aerobic and anaerobic processes, forming the basis of biological treatment.

• In a wastewater lagoon system, what is the main mechanism for

pathogen removal?

• Filtration
• Sunlight and natural die-off
• Chlorination
• Sedimentation 2 / 4

Rationale: In lagoons, pathogens are primarily removed by sunlight

(UV radiation) and natural die-off due to environmental conditions over time.

• What does BOD stand for in wastewater treatment?
• Basic Oxygen Demand
• Biochemical Oxygen Density
• Biochemical Oxygen Demand
• Bacterial Oxidation Data

Rationale: BOD measures the amount of dissolved oxygen consumed

by microorganisms to decompose organic matter in wastewater, reflecting its organic pollution load.

• Which of the following is a primary treatment process?
• Activated sludge
• Trickling filter
• Sedimentation
• Nitrification

Rationale: Primary treatment removes settleable solids through

sedimentation before biological treatment.

• What is the main purpose of aeration in a wastewater treatment

plant?

• To heat the water
• To remove chlorine
• To supply oxygen for microbial activity 3 / 4

• To increase pH

Rationale: Aeration provides oxygen to aerobic bacteria, which

decompose organic matter efficiently.

• Which chemical is commonly used for disinfection in wastewater

treatment?

• Ammonia
• Ozone
• Chlorine
• Fluoride

Rationale: Chlorine is widely used to disinfect treated wastewater

before discharge, killing pathogenic microorganisms.

• What is the typical temperature range for biological treatment in

activated sludge processes?

A. 0–5°C

B. 5–10°C

C. 15–35°C

D. 40–50°C

Rationale: Biological treatment is most efficient in the mesophilic

range (15–35°C), where bacteria metabolize organic matter effectively.

• Which of the following is an example of tertiary treatment?
• Sedimentation
• Nutrient removal
• / 4