Operator Class II Exam Practice

Nova Scotia Wastewater Treatment Operator Class II Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• The primary purpose of primary sedimentation in wastewater

treatment is to:

• Remove dissolved nutrients
• Remove settleable solids
• Disinfect wastewater
• Reduce biochemical oxygen demand

Rationale: Primary sedimentation allows heavier solids to settle out,

reducing the load on secondary treatment.

• Which of the following is a common method for measuring sludge

volume index (SVI)? 1 / 4

• pH meter
• Graduated cylinder method
• Turbidity meter
• Conductivity meter

Rationale: SVI is measured by settling a known volume of mixed liquor in a

cylinder and calculating the volume of settled sludge.

3. The purpose of aeration in activated sludge systems is to:

• Settle solids
• Supply oxygen for microbial activity
• Filter wastewater
• Remove nutrients

Rationale: Aeration provides oxygen to microorganisms to metabolize

organic matter.

• Which type of bacteria is primarily responsible for nitrification in

wastewater treatment?

• Coliform bacteria
• Nitrosomonas and Nitrobacter
• Anaerobic bacteria
• Pseudomonas

Rationale: Nitrifying bacteria convert ammonia to nitrite (Nitrosomonas)

and nitrite to nitrate (Nitrobacter). 2 / 4

5. The term “BOD” stands for:

• Biological Oxidation Demand
• Biochemical Oxygen Demand
• Bacterial Oxygen Depletion
• Basic Organic Decomposition

Rationale: BOD measures the amount of oxygen required by microorganisms

to decompose organic matter.

6. In wastewater, TSS stands for:

• Total Soluble Substances
• Total Suspended Solids
• Total Sanitary Solids
• Total Sediment Suspended

Rationale: TSS measures the concentration of suspended solids in water,

affecting treatment performance.

7. The typical pH range for nitrification is:

A) 3.5 – 5.0

B) 6.0 – 7.0

C) 6.5 – 8.0

D) 8.5 – 10.0

Rationale: Nitrifying bacteria function optimally in a slightly alkaline to

neutral pH range. 3 / 4

8. Chlorine is commonly used in wastewater treatment for:

• Flocculation
• Disinfection
• Filtration
• Aeration

Rationale: Chlorine inactivates pathogens to protect public health.

9. The main purpose of secondary treatment is to:

• Remove settleable solids
• Reduce organic matter and BOD
• Disinfect wastewater
• Adjust pH

Rationale: Secondary treatment uses biological processes to remove

dissolved and suspended organic matter.

10. Sludge digestion is primarily used to:

• Remove solids
• Increase BOD
• Stabilize organic matter
• Remove nutrients

Rationale: Anaerobic or aerobic digestion reduces odor, pathogens, and

organic content in sludge.

• Which of the following is a typical method for solids removal

before secondary treatment?

• / 4