Practice Exam Questions And Correct

Kansas Wastewater Operator Class I 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
• Provide drinking water
• Remove pollutants from wastewater before discharge
• Produce fertilizer

Rationale: The main goal of a wastewater treatment plant is to remove

physical, chemical, and biological contaminants to protect public health and the environment.

• What is the typical pH range for wastewater entering a treatment plant?

A. 2–4 1 / 4

B. 6–9

C. 10–12

D. 4–5

Rationale: Most municipal wastewater has a near-neutral pH, generally

between 6 and 9.

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

Rationale: Sedimentation is a primary treatment process that removes

settleable solids from wastewater.

• What does BOD measure?
• Biological oxygen produced
• Amount of oxygen required by microorganisms to decompose organic

matter

• Total dissolved solids
• Chemical oxygen demand

Rationale: BOD (Biochemical Oxygen Demand) indicates the organic

matter in wastewater by measuring oxygen consumption during microbial decomposition.

• What is the main function of aeration in secondary treatment?
• Kill bacteria 2 / 4

• Remove solids
• Supply oxygen to microorganisms
• Reduce pH

Rationale: Aeration provides dissolved oxygen to support microbial activity

in the biological treatment process.

• Which type of sludge is produced in primary clarifiers?
• Activated sludge
• Primary sludge
• Digested sludge
• Trickling filter sludge

Rationale: Primary clarifiers remove settleable solids, producing primary

sludge.

7. Nitrification is the biological conversion of:

• Ammonia to nitrogen gas
• Ammonia to nitrate
• Nitrate to ammonia
• Nitrogen gas to nitrate

Rationale: Nitrification is a two-step aerobic process in which ammonia is

converted to nitrite and then to nitrate by nitrifying bacteria.

8. Denitrification occurs under:

• Aerobic conditions
• Anaerobic conditions
• Neutral pH 3 / 4

• High temperatures

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

oxygen-limited (anaerobic) conditions.

• What is the main purpose of chlorination?
• Remove solids
• Reduce BOD
• Disinfect treated effluent
• Adjust pH

Rationale: Chlorination is used to kill pathogenic microorganisms in

treated wastewater before discharge.

• Which of the following is considered a secondary treatment method?
• Sedimentation
• Activated sludge process
• Screening
• Grit removal

Rationale: Secondary treatment uses biological processes like activated

sludge to remove dissolved and suspended organic matter.

• What is the typical retention time in a primary clarifier?
• 5–10 minutes
• 1–2 hours
• 6–12 hours
• 24 hours
• / 4