Exam Practice Questions And Correct

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

1. The primary purpose of a wastewater treatment plant is to:

• Generate electricity
• Protect public health and the environment
• Increase water hardness
• Reduce turbidity for drinking water

Answer: Protect public health and the environment

Rationale: Wastewater treatment plants remove contaminants to prevent

disease, protect ecosystems, and ensure water quality before discharge.

• Which of the following is considered a primary treatment process?
• Trickling filter 1 / 4

• Activated sludge
• Sedimentation
• Chlorination

Answer: Sedimentation

Rationale: Primary treatment involves physical removal of settleable solids

through sedimentation.

3. BOD (Biochemical Oxygen Demand) measures:

• Dissolved oxygen in water
• The amount of oxygen required by microorganisms to decompose

organic matter

• Nutrient concentrations
• pH levels

Answer: The amount of oxygen required by microorganisms to decompose

organic matter

Rationale: BOD quantifies the organic load in wastewater by measuring

oxygen consumption during decomposition.

• Which microorganism is primarily responsible for nitrification in

wastewater treatment?

• Escherichia coli
• Streptococcus
• Nitrosomonas and Nitrobacter
• Pseudomonas 2 / 4

Answer: Nitrosomonas and Nitrobacter

Rationale: Nitrosomonas converts ammonia to nitrite, and Nitrobacter

converts nitrite to nitrate during nitrification.

• What is the purpose of sludge thickening?
• Reduce BOD
• Decrease water content of sludge
• Increase nutrient levels
• Sterilize sludge

Answer: Decrease water content of sludge

Rationale: Thickening reduces sludge volume, making subsequent handling

and treatment more efficient.

• Which of the following best describes a trickling filter?
• A chemical disinfection process
• A primary clarifier
• A fixed-bed biological treatment system
• A membrane filtration system

Answer: A fixed-bed biological treatment system

Rationale: Trickling filters provide a surface for microbial growth to

biologically treat wastewater.

7. TSS in wastewater stands for:

• Total Salt Solution
• Total Suspended Solids 3 / 4

• Total Sulfate Solids
• Total Soluble Substances

Answer: Total Suspended Solids

Rationale: TSS measures the solid particles suspended in wastewater, which

are removed through sedimentation or filtration.

8. The main function of aeration in an activated sludge system is to:

• Settle solids
• Provide oxygen for microbial growth
• Remove nitrogen chemically
• Filter solids

Answer: Provide oxygen for microbial growth

Rationale: Aeration supplies oxygen necessary for aerobic bacteria to

decompose organic matter.

9. A common method for disinfecting wastewater is:

• Filtration
• Chlorination
• Sedimentation
• Nitrification

Answer: Chlorination

Rationale: Chlorine effectively kills pathogens before treated water is

discharged or reused.

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