Operator Level 3 Exam Practice

Prince Edward Island Wastewater Operator Level 3 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 generate electricity
• To remove solid waste only
• To protect public health and the environment
• To supply drinking water
• To protect public health and the environment

Rationale: Wastewater treatment plants are designed to remove

contaminants from wastewater to prevent disease, protect the environment, and ensure safe discharge. 1 / 4

• What is the typical pH range for biologically treated wastewater

before discharge?

A. 3–5

B. 6–9

C. 10–12

D. 4–6

B. 6–9

Rationale: Most biological treatment processes function effectively

within a near-neutral pH range of 6–9.

• Which of the following is a common method for primary solids

removal?

• Activated sludge
• Sedimentation
• Chlorination
• Nitrification
• Sedimentation

Rationale: Sedimentation in primary clarifiers removes settleable

solids from raw wastewater.

• In a secondary treatment process, which microorganism type is

primarily responsible for organic matter breakdown?

• Algae
• Protozoa
• Bacteria 2 / 4

• Fungi
• Bacteria

Rationale: Bacteria metabolize organic matter in secondary treatment

processes, such as activated sludge and trickling filters.

• Which type of sludge is generated from secondary treatment?
• Primary sludge
• Secondary sludge (waste activated sludge)
• Tertiary sludge
• Industrial sludge
• Secondary sludge (waste activated sludge)

Rationale: Secondary treatment produces waste activated sludge,

which contains microorganisms that have grown during biological treatment.

• What is the main purpose of chlorination in wastewater treatment?
• Remove solids
• Kill pathogens
• Reduce BOD
• Neutralize pH
• Kill pathogens

Rationale: Chlorination disinfects treated wastewater to reduce the

risk of disease-causing microorganisms.

• Which of the following is considered a tertiary treatment method?
• Primary sedimentation 3 / 4

• Trickling filter
• Filtration and nutrient removal
• Screening
• Filtration and nutrient removal

Rationale: Tertiary treatment provides advanced polishing to remove

nutrients, fine solids, or residual contaminants.

• What does BOD stand for in wastewater treatment?
• Biochemical Oxygen Demand
• Basic Oxygen Diffusion
• Biological Oxidation Depth
• Biotic Oxidation Density
• Biochemical Oxygen Demand

Rationale: BOD measures the amount of oxygen required by

microorganisms to decompose organic matter in wastewater.

• Which factor most directly affects biological treatment efficiency?
• Influent color
• Temperature
• Odor
• TSS alone
• Temperature

Rationale: Temperature influences microbial activity, with lower

temperatures slowing biological processes.

• / 4