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New Hampshire Wastewater Operator Grade II 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
- Remove contaminants from wastewater
- Store stormwater
- Produce drinking water
Answer: B
Rationale: The primary purpose of a wastewater treatment plant is to
remove physical, chemical, and biological contaminants from wastewater before discharge to protect public health and the environment.
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- Which of the following is a characteristic of primary treatment?
- Biological nutrient removal
- Sedimentation of suspended solids
- Advanced filtration
- Disinfection
Answer: B
Rationale: Primary treatment involves the physical removal of solids through
sedimentation, reducing the load for secondary treatment.
- What is BOD in wastewater treatment?
- Biological Oxidation Density
- Biochemical Oxygen Demand
- Biochemical Oxygen Demand
- Basic Oxidation Device
Answer: C
Rationale: BOD measures the amount of oxygen microorganisms require to
decompose organic matter in water over a specific time, indicating pollution strength.
4. The typical range of BOD in domestic wastewater is:
- 50–100 mg/L
- 200–300 mg/L 2 / 4
- 500–700 mg/L
- 800–1000 mg/L
Answer: B
Rationale: Domestic wastewater typically has a BOD of 200–300 mg/L,
which reflects the organic load entering treatment systems.
- Which organism is primarily responsible for biological treatment in
- Fish
- Viruses
- Bacteria
- Protozoa
activated sludge?
Answer: C
Rationale: Bacteria metabolize organic matter in the activated sludge
process, forming flocs that settle in secondary clarifiers.
- What is the main purpose of a grit chamber?
- Remove grease
- Remove sand and heavy inorganic solids
- Aerate wastewater
- Reduce BOD 3 / 4
Answer: B
Rationale: Grit chambers remove sand, gravel, and other heavy solids to
protect pumps and equipment from abrasion.
- Which of the following processes is considered secondary treatment?
- Screening
- Activated sludge
- Sedimentation
- Disinfection
Answer: B
Rationale: Secondary treatment biologically removes dissolved and
suspended organic matter, with activated sludge being a common method.
8. Chlorination in wastewater treatment is primarily used for:
- Nutrient removal
- Disinfection
- Aeration
- Sludge thickening
Answer: B
Rationale: Chlorination kills pathogenic microorganisms to reduce health
risks in effluent discharged to surface waters.
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