Operator Level 2 Exam Practice

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

• Which process is primarily used for removing settleable solids from

wastewater?

• Filtration
• Coagulation
• Sedimentation
• Chlorination

Rationale: Sedimentation allows heavier solids to settle out of

wastewater by gravity, making it the primary method for solids removal. 1 / 4

• What is the main purpose of aeration in activated sludge systems?
• To disinfect wastewater
• To supply oxygen to microorganisms
• To remove grease
• To settle solids

Rationale: Aeration provides dissolved oxygen that supports

microbial metabolism, which is essential for biological treatment.

• Which of the following is a common indicator of organic pollution in

wastewater?

• pH
• Biochemical Oxygen Demand (BOD)
• Nitrate concentration
• Chlorine residual

Rationale: BOD measures the oxygen required for microbial

decomposition of organic matter, indicating organic pollution levels.

4. The process of converting ammonia to nitrate by bacteria is called:

• Denitrification
• Nitrification
• Filtration
• Coagulation

Rationale: Nitrification is a biological process where ammonia is

oxidized to nitrite and then to nitrate by nitrifying bacteria. 2 / 4

• Which microorganism is primarily responsible for nitrification?
• Escherichia coli
• Nitrosomonas and Nitrobacter
• Streptococcus
• Pseudomonas

Rationale: Nitrosomonas oxidizes ammonia to nitrite, and

Nitrobacter oxidizes nitrite to nitrate in nitrification.

6. The most common method for disinfection of wastewater is:

• Filtration
• Sedimentation
• Chlorination
• Coagulation

Rationale: Chlorination is widely used to kill pathogens in treated

wastewater before discharge.

• Which unit process removes suspended solids by chemical means?
• Biological treatment
• Filtration
• Coagulation and flocculation
• Aeration

Rationale: Coagulation destabilizes colloidal particles, and

flocculation aggregates them into larger particles that can settle.

• What is the primary purpose of a grit chamber?
• Remove organic matter 3 / 4

• Remove sand, gravel, and other heavy inorganic particles
• Reduce BOD
• Remove pathogens

Rationale: Grit chambers slow the flow to allow heavy inorganic

particles to settle before biological treatment.

• Which parameter indicates the strength of wastewater?
• pH
• Temperature
• BOD and COD
• Color

Rationale: BOD and COD quantify the organic load, which indicates

wastewater strength.

• What is the typical detention time in a primary clarifier?
• 10–20 minutes
• 30–60 minutes
• 1–2 hours
• 4–6 hours

Rationale: Primary clarifiers usually retain wastewater long enough

(1–2 hours) to allow settleable solids to settle.

• Which of the following affects the efficiency of sedimentation

tanks?

• Temperature
• Flow rate
• / 4