Level 2 Practice Exam Questions And

Yukon Wastewater Treatment Operator Level 2 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?
• Generate electricity
• Remove solids and contaminants from wastewater
• Increase water hardness
• Produce potable water

Answer: B) Remove solids and contaminants from wastewater

Rationale: The main goal of wastewater treatment is to remove physical,

chemical, and biological contaminants from sewage before releasing it into the environment.

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• Which of the following is a common biological process in secondary

wastewater treatment?

• Sedimentation
• Chlorination
• Activated sludge
• Screening

Answer: C) Activated sludge

Rationale: Activated sludge is a biological process where microorganisms

consume organic matter in wastewater.

• The pH of typical untreated domestic wastewater is usually in the range

of:

A) 2–3

B) 6–8

C) 9–11

D) 12–14

Answer: B) 6–8

Rationale: Domestic wastewater generally has a near-neutral pH, making

it suitable for biological treatment processes.

• What is the purpose of screening in wastewater treatment?
• Remove dissolved chemicals 2 / 4

• Remove large debris and solids
• Disinfect water
• Reduce nutrient concentrations

Answer: B) Remove large debris and solids

Rationale: Screening removes large objects such as rags, sticks, and

plastics that can damage equipment downstream.

• Which parameter measures the amount of oxygen consumed by

microorganisms while decomposing organic matter in water?

• Total Suspended Solids (TSS)
• Biological Oxygen Demand (BOD)
• Chemical Oxygen Demand (COD)
• pH

Answer: B) Biological Oxygen Demand (BOD)

Rationale: BOD measures the oxygen required by bacteria to biologically

degrade organic matter.

• What is the function of a grit chamber in wastewater treatment?
• Remove heavy metals
• Settle sand, gravel, and grit
• Kill pathogens
• Neutralize acids 3 / 4

Answer: B) Settle sand, gravel, and grit

Rationale: Grit chambers allow heavy inorganic particles to settle out,

preventing wear on pumps and other equipment.

• Which of the following is a primary treatment process?
• Chlorination
• Sedimentation
• Activated sludge
• Filtration

Answer: B) Sedimentation

Rationale: Sedimentation removes settleable solids from wastewater by

gravity before secondary treatment.

• What is the main purpose of secondary treatment?
• Remove pathogens
• Remove suspended solids
• Remove dissolved and colloidal organic matter
• Neutralize pH

Answer: C) Remove dissolved and colloidal organic matter

Rationale: Secondary treatment focuses on biologically degrading organic

pollutants that remain after primary treatment.

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