Exam Practice Questions And Correct

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

• What is the primary purpose of a wastewater treatment plant?
• To generate electricity
• To remove pollutants from wastewater
• To increase wastewater flow
• To produce drinking water

Answer: B. To remove pollutants from wastewater

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

chemical, and biological pollutants to protect public health and the environment.

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• Which of the following is a common method of primary treatment?
• Activated sludge
• Sedimentation
• Nitrification
• Disinfection

Answer: B. Sedimentation

Rationale: Primary treatment involves physical processes like sedimentation

to remove settleable solids from wastewater.

3. In wastewater treatment, BOD stands for:

• Biological Oxygen Demand
• Biochemical Oxygen Diffusion
• Biological Oxidation Dose
• Basic Oxygen Dilution

Answer: A. Biological Oxygen Demand

Rationale: BOD measures the amount of oxygen microorganisms need to

decompose organic matter in water.

• What is the typical range of BOD removal in secondary treatment?

A. 10–20%

B. 30–40% 2 / 4

C. 85–95%

D. 100%

Answer: C. 85–95%

Rationale: Secondary treatment processes, such as activated sludge,

typically remove 85–95% of the BOD from wastewater.

• Which microorganism type is primarily responsible for breaking down

organic matter in an activated sludge system?

• Viruses
• Protozoa
• Bacteria
• Algae

Answer: C. Bacteria

Rationale: Bacteria metabolize organic matter, forming flocs that settle in

secondary clarifiers.

• What is the purpose of an aeration tank in activated sludge treatment?
• To disinfect wastewater
• To provide oxygen for microorganisms
• To remove large solids
• To increase water temperature 3 / 4

Answer: B. To provide oxygen for microorganisms

Rationale: Aeration supplies dissolved oxygen, which is critical for aerobic

bacteria to degrade organic pollutants.

• Which process converts ammonia into nitrate?
• Denitrification
• Nitrification
• Chlorination
• Filtration

Answer: B. Nitrification

Rationale: Nitrification is a two-step biological process where ammonia is

oxidized to nitrite and then to nitrate by bacteria.

8. Denitrification is important in wastewater treatment because it:

• Produces oxygen
• Removes nitrogen compounds
• Increases sludge production
• Removes phosphorus

Answer: B. Removes nitrogen compounds

Rationale: Denitrification converts nitrates into nitrogen gas, reducing

nutrient pollution in receiving waters.

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