Level III Practice Exam Questions And

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

• What is the primary purpose of a wastewater treatment plant?

a) Produce potable water

b) Protect public health and the environment by treating wastewater

c) Generate electricity

d) Provide irrigation water

Rationale: The main goal of wastewater treatment is to remove

contaminants and protect public health and the environment.

• Which parameter is most commonly used to measure organic strength

in wastewater?

• pH 1 / 4

b) Biochemical Oxygen Demand (BOD)

c) Total Suspended Solids (TSS)

d) Conductivity

Rationale: BOD measures the amount of oxygen required by

microorganisms to decompose organic matter in wastewater.

• What is the typical range of pH in treated municipal wastewater

discharge?

• 3–5
• 6–7
• 6.5–9
• 9–11

Rationale: Treated wastewater should generally have a pH near

neutral, usually between 6.5 and 9.

• What type of microorganism is primarily responsible for nitrification in

wastewater?

a) Anaerobic bacteria

b) Chemolithotrophic bacteria

c) Protozoa

d) Fungi

Rationale: Nitrifying bacteria, such as Nitrosomonas and Nitrobacter,

oxidize ammonia to nitrate.

• In activated sludge, what does the term “sludge age” refer to?

a) Age of the influent wastewater 2 / 4

b) Time sludge spends in the primary clarifier

c) Average time microorganisms remain in the system

d) Time for sludge to settle in the digester

Rationale: Sludge age (or solids retention time) is the average

duration microorganisms stay in the activated sludge system, affecting treatment efficiency.

• Which of the following is a common method of removing solids from

wastewater?

a) Sedimentation

b) Filtration

c) Chlorination

d) Aeration

Rationale: Sedimentation allows solids to settle out by gravity in

clarifiers or settling tanks.

• What is the main purpose of chlorination in wastewater treatment?

a) Reduce BOD

b) Remove solids

c) Disinfect and kill pathogens

d) Enhance settling

Rationale: Chlorination is used primarily for disinfection to kill

disease-causing organisms.

• Which of the following is a characteristic of anaerobic digestion?

a) Requires oxygen 3 / 4

b) Produces nitrate

c) Produces methane gas

d) Rapidly reduces TSS without odor

Rationale: Anaerobic digestion decomposes organic matter in the

absence of oxygen, producing methane and CO₂.

• What is the purpose of a grit chamber?

a) Reduce BOD

b) Remove sand, gravel, and other heavy inorganic solids

c) Aerate wastewater

d) Neutralize pH

Rationale: Grit chambers remove dense inorganic particles to prevent

damage to downstream equipment.

• What is the typical temperature range for mesophilic anaerobic

digestion?

• 5–15°C
• 30–38°C
• 50–60°C
• 70–80°C

Rationale: Mesophilic digestion occurs efficiently in the range of 30–

38°C.

• Which sludge dewatering process uses high-speed centrifugal

force?

a) Belt press

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