Class II Exam Practice Questions And

Kentucky 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 preliminary treatment in a wastewater

treatment plant is to:

• Remove nutrients
• Remove large solids and grit
• Reduce BOD
• Disinfect wastewater

Answer: B

Rationale: Preliminary treatment removes large solids, grit, and debris to

protect downstream equipment and prevent clogging. 1 / 4

• Which of the following is the main source of BOD in municipal

wastewater?

• Industrial chemicals
• Organic matter from human waste and food
• Sand and grit
• Heavy metals

Answer: B

Rationale: Biochemical Oxygen Demand (BOD) primarily comes from

biodegradable organic matter, including human waste and food residues.

3. Grit chambers are designed to remove:

• Suspended bacteria
• Sand, gravel, and other dense inorganic particles
• Oils and grease
• Dissolved nutrients

Answer: B

Rationale: Grit chambers remove dense inorganic particles that can settle

quickly, protecting pumps and other equipment.

4. The purpose of primary sedimentation is to:

• Remove dissolved solids
• Settle suspended solids
• Reduce nutrient concentration
• Aerate wastewater 2 / 4

Answer: B

Rationale: Primary sedimentation allows heavier suspended solids to settle

out of the wastewater for further treatment.

5. The term “sludge age” in activated sludge systems refers to:

• Age of the wastewater
• Average time microorganisms remain in the system
• Age of the clarifier
• Retention time of treated effluent

Answer: B

Rationale: Sludge age, or mean cell residence time, indicates how long

microorganisms are maintained in the activated sludge system.

6. The main function of an aeration tank is to:

• Provide oxygen for microbial decomposition
• Remove grit
• Settle solids
• Disinfect effluent

Answer: A

Rationale: Aeration tanks supply oxygen to microorganisms that break down

organic matter in wastewater.

7. Nitrification in wastewater treatment converts:

• Nitrogen gas to ammonia
• Ammonia to nitrate 3 / 4

• Organic nitrogen to phosphorus
• Nitrate to ammonia

Answer: B

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

oxidized first to nitrite and then to nitrate.

• Denitrification occurs under which conditions?
• Aerobic
• Anoxic
• Hypoxic
• None of the above

Answer: B

Rationale: Denitrification is the reduction of nitrate to nitrogen gas under

anoxic (oxygen-limited) conditions.

9. Chlorine is used in wastewater treatment primarily for:

• pH adjustment
• Disinfection
• Flocculation
• Aeration

Answer: B

Rationale: Chlorine is a common disinfectant that destroys pathogenic

microorganisms in treated effluent.

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