Practice Exam Questions And Correct

Texas Wastewater Operator Class A 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?
• Produce drinking water
• Remove pollutants from wastewater before discharge
• Generate electricity
• Irrigate crops

Rationale: Wastewater treatment plants are designed to remove

contaminants and protect public health and the environment.

• What is BOD a measure of in wastewater?
• pH level
• Oxygen demand of biodegradable material 1 / 4

• Nutrient concentration
• Temperature

Rationale: Biochemical Oxygen Demand (BOD) indicates the amount of

dissolved oxygen required by microorganisms to break down organic material.

• Which microorganism is most commonly responsible for secondary

treatment in activated sludge systems?

• Algae
• Viruses
• Bacteria
• Protozoa

Rationale: Bacteria metabolize organic matter in the activated sludge

process, reducing BOD.

• What is the typical range of pH for municipal wastewater?

A. 2–4

B. 6–9

C. 10–12

D. 4–5

Rationale: Most municipal wastewater has a pH between 6 and 9, suitable

for microbial activity.

• What is the main function of a grit chamber?
• Remove dissolved oxygen 2 / 4

• Settle out sand, gravel, and other heavy particles
• Reduce nitrogen
• Neutralize pH

Rationale: Grit chambers slow flow to allow heavy inorganic particles to

settle.

• Which of the following is a primary treatment process?
• Activated sludge
• Trickling filter
• Sedimentation
• Aerated lagoon

Rationale: Primary treatment removes settleable solids and some organic

material via sedimentation.

7. Nitrification in wastewater treatment converts:

• Nitrate to ammonium
• Nitrite to nitrogen gas
• Ammonium to nitrate
• Organic nitrogen to protein

Rationale: Nitrification is the biological conversion of ammonium to nitrate

by autotrophic bacteria.

8. Denitrification converts nitrate into:

• Ammonium
• Nitrite 3 / 4

• Nitrogen gas
• Organic nitrogen

Rationale: Denitrification is an anaerobic process converting nitrate into

gaseous nitrogen, reducing nutrient load.

• What is the purpose of chlorination in wastewater treatment?
• Remove heavy metals
• Increase pH
• Disinfect the effluent
• Reduce BOD

Rationale: Chlorination is used to kill pathogens and protect public health

before discharge.

• The normal dissolved oxygen (DO) range in activated sludge

aeration tanks is:

• 0–1 mg/L
• 2–3 mg/L
• 1.5–2.5 mg/L
• 5–10 mg/L

Rationale: Maintaining DO around 1.5–2.5 mg/L ensures effective aerobic

microbial activity without wasting energy.

• What is the typical sludge age for an extended aeration system?
• 1–2 days
• 3–5 days
• / 4