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Oklahoma Wastewater Operator Class B 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?
- To produce drinking water
- To remove contaminants from wastewater
- To generate electricity
- To supply water for irrigation
Answer: B
Rationale: The primary purpose of a wastewater treatment plant is to
remove physical, chemical, and biological contaminants from wastewater before it is discharged to the environment. 1 / 4
- Which process is typically used to remove settleable solids in primary
- Filtration
- Disinfection
- Sedimentation
- Chlorination
treatment?
Answer: C
Rationale: Sedimentation allows solids to settle by gravity in primary
clarifiers.
3. In wastewater treatment, BOD stands for:
- Biological Oxidation Demand
- Basic Organic Dissolution
- Biochemical Oxygen Demand
- Biochemical Oxidation Data
Answer: C
Rationale: BOD measures the amount of oxygen required by microorganisms
to decompose organic matter in water.
- Which of the following is an example of a physical treatment process?
- Activated sludge
- Screening
- Trickling filter
- Chlorination 2 / 4
Answer: B
Rationale: Screening physically removes large solids from wastewater.
- What is the main purpose of aeration in secondary treatment?
- To settle solids
- To remove grease
- To supply oxygen for biological treatment
- To disinfect wastewater
Answer: C
Rationale: Aeration provides oxygen to microorganisms for the breakdown
of organic pollutants.
6. Sludge volume index (SVI) is used to evaluate:
- Chlorine demand
- Dissolved oxygen
- Settling characteristics of activated sludge
- pH stability
Answer: C
Rationale: SVI measures how well sludge settles, which is crucial for clarifier
design and operation.
7. Nitrification in wastewater treatment converts:
- Nitrite to nitrogen gas
- Ammonia to nitrate 3 / 4
- Organic carbon to methane
- Phosphate to phosphate rock
Answer: B
Rationale: Nitrification is a two-step aerobic process that converts ammonia
to nitrite and then to nitrate.
8. Denitrification is a process that converts nitrate to:
- Ammonia
- Nitrite
- Nitrogen gas
- Phosphate
Answer: C
Rationale: Denitrification occurs under anoxic conditions, removing nitrogen
from wastewater as nitrogen gas.
- Which of the following can affect the rate of biological treatment?
- Temperature
- pH
- Dissolved oxygen
- All of the above
Answer: D
Rationale: Temperature, pH, and dissolved oxygen all influence microbial
activity and treatment efficiency.
- / 4
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