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Wisconsin Wastewater Operator Basic Exam And ( Answers) Plus Rationales 2026 Q&A Instant Download Pdf
- What is the primary purpose of a wastewater treatment plant?
- Produce drinking water
- Remove pollutants from wastewater
- Generate electricity
- Irrigate crops
Rationale: The main goal of wastewater treatment is to remove
contaminants to protect public health and the environment.
- Which of the following is a common primary treatment method?
- Biological nutrient removal 1 / 4
- Activated sludge
- Sedimentation
- Disinfection
Rationale: Sedimentation allows solids to settle out of wastewater as part of
primary treatment.
- What is the typical pH range for wastewater entering a treatment
plant?
A. 2–4
B. 9–11
C. 6–9
D. 11–14
Rationale: Most municipal wastewater has a near-neutral pH, usually
between 6 and 9.
- The process of removing large solids at the beginning of treatment is
called:
- Filtration
- Coagulation
- Screening
- Chlorination 2 / 4
Rationale: Screening removes rags, sticks, and other large debris before it
can damage equipment.
- What is the main function of aeration in secondary treatment?
- Remove grit
- Provide oxygen for microorganisms
- Settle solids
- Neutralize pH
Rationale: Aeration supplies oxygen needed for aerobic bacteria to break
down organic matter.
- Which unit process removes fine suspended solids after primary
- Screening
- Secondary clarification
- Grit removal
- Disinfection
treatment?
Rationale: Secondary clarifiers allow biological flocs to settle, removing fine
solids.
- Which of the following microorganisms is commonly used in activated
sludge systems? 3 / 4
- Virus
- Bacteria
- Protozoa
- Algae
Rationale: Bacteria are the primary agents that digest organic matter in
activated sludge.
8. BOD stands for:
- Biotic Oxygen Demand
- Biochemical Oxygen Demand
- Biological Oxidation Device
- Basic Oxygen Dissolution
Rationale: BOD measures the amount of oxygen required by microorganisms
to decompose organic matter.
9. A high BOD in influent wastewater indicates:
- Low organic content
- High chlorine content
- High organic pollution
- Low nitrogen content
Rationale: BOD reflects the amount of biodegradable organic matter in the
wastewater.
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