Wastewater Operator Class I Exam: Questions & Answers update

Wastewater Operator Class I Licensing Ex n n n n n




am Practice Questions And Correct Answe
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rs (Verified Answers) Plus Rationales 202
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6 Q&A | Instant Download Pdf
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1. What is the primary purpose of a wastewater treatment plant?
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A. Generate electricity n




B. Remove contaminants from wastewater
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C. Increase water hardness
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D. Produce drinking water
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Rationale: The primary purpose of a wastewater treatment plant is to remo
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ve physical, chemical, and biological contaminants from wastewater before
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discharging it into the environment.
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2. Which of the following is considered a physical treatment process?
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A. Chlorination

, B. Sedimentation
C. Biological filtration n




D. Aeration

Rationale: Sedimentation is a physical process that removes suspended solid
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s by allowing them to settle under gravity.
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3. In wastewater terminology, BOD stands for:
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A. Biological Oxidation Demand n n




B. Biochemical Oxygen Determination n n




C. Biochemical Oxygen Demand n n




D. Biological Oxidation Depth n n




Rationale: BOD measures the amount of dissolved oxygen needed by microo
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rganisms to break down organic matter in water.
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4. Which unit process is primarily used to remove suspended solids?
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A. Disinfection
B. Aeration
C. Filtration
D. Sedimentation

Rationale: Sedimentation removes suspended solids from wastewater by gr
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avity settling.
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5. What is the typical range of BOD in domestic wastewater?
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A. 10–50 mg/L n




B. 50–100 mg/L n

, C. 200–300 mg/L n




D. 500–800 mg/L n




Rationale: Domestic wastewater usually contains BOD levels between 200–
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300 mg/L.
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6. Which of the following is a characteristic of primary treatment?
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A. Biological nutrient removal
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B. Removal of settleable solids
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C. Advanced filtration n




D. Chemical coagulation n




Rationale: Primary treatment focuses on removing settleable solids and floa
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ting material.
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7. Chlorination is used primarily for:
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A. Disinfection
B. Sedimentation
C. Biological treatment n




D. Filtration

Rationale: Chlorination kills or inactivates pathogens in wastewater to reduc
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e disease risk.
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8. Sludge digestion is primarily intended to:
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A. Remove heavy metals
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B. Stabilize organic solids
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, C. Reduce chlorine demand n n




D. Increase BOD n




Rationale: Sludge digestion stabilizes organic matter in sludge, reducing odo
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rs and pathogen content.
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9. Which of the following is NOT a type of wastewater?
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A. Domestic
B. Industrial
C. Stormwater
D. Groundwater

Rationale: Groundwater is naturally occurring water below the surface, not
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wastewater.
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10. What is the main function of an aeration basin in secondary t
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reatment?
A. Remove grit n




B. Provide oxygen for biological processes
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C. Settle solids n




D. Filter water n




Rationale: Aeration basins supply oxygen to microorganisms to biodegrade
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organic pollutants.
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11. Which microorganism is commonly used in activated sludge
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systems?
A. Virus