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West Virginia Wastewater Class IV Operator Practice Exam Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf
- Which of the following is the primary purpose of a wastewater
- To produce drinking water
- To remove contaminants from wastewater before discharge
- To store wastewater for industrial use
- To desalinate seawater
treatment plant?
Rationale: The main function of a wastewater treatment plant is to treat
sewage to reduce pollutants and protect public health and the environment. 1 / 4
- What is the typical range of BOD5 removal in a conventional activated
sludge process?
A. 20–40%
B. 40–60%
C. 80–90%
D. 95–100%
Rationale: Activated sludge processes are designed to achieve high organic
matter removal, usually around 80–90% BOD5 reduction.
- What does TSS stand for in wastewater terminology?
- Total Soluble Substances
- Total Sanitary Solids
- Total Suspended Solids
- Total Sulfide Solution
Rationale: TSS measures the concentration of suspended particles in
wastewater, which can affect treatment efficiency and discharge compliance.
4. Nitrification in a wastewater treatment plant converts:
- Ammonia to nitrogen gas
- Ammonia to nitrate
- Nitrate to ammonia
- Nitrite to ammonia 2 / 4
Rationale: Nitrification is a biological process in which ammonia is oxidized
first to nitrite and then to nitrate.
5. Denitrification is a process that:
- Converts nitrate to ammonia
- Converts ammonia to nitrate
- Converts nitrate to nitrogen gas
- Removes solids from wastewater
Rationale: Denitrification occurs under anoxic conditions, reducing nitrate
to nitrogen gas, thus removing nitrogen from wastewater.
- What is the typical detention time in a primary clarifier?
- 5–10 minutes
- 15–30 minutes
- 1–2 hours
- 6–8 hours
Rationale: Primary clarifiers are designed to allow suspended solids to
settle; typical detention time is 1–2 hours.
- Which chemical is commonly used for phosphorus removal in
- Sodium hypochlorite
- Alum (Aluminum sulfate)
- Calcium hydroxide
- Ferric chloride only 3 / 4
wastewater?
Rationale: Alum reacts with soluble phosphorus to form insoluble
precipitates, which can then settle in sedimentation tanks.
- What is the purpose of chlorination in wastewater treatment?
- Disinfection to kill pathogens
- Removal of suspended solids
- Nitrification
- Phosphorus precipitation
Rationale: Chlorination is used to disinfect effluent before discharge to
protect public health.
- What is the typical pH range for an activated sludge process?
A. 4.5–5.5
B. 5.5–6.5
C. 6.5–8.5
D. 9–10.5
Rationale: Activated sludge bacteria thrive in a near-neutral pH
environment, generally 6.5–8.5.
- Which microorganism is primarily responsible for nitrification?
- Nitrosomonas and Nitrobacter
- Escherichia coli
- Bacillus subtilis
- Streptococcus faecalis
- / 4
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