Texas Wastewater Operator Class A License Exam Practice Questions & Answers 2026 | Instant PDF

Texas Wastewater Operator Class A Pract
f f f f f




ice Exam Questions And Correct Answers (
f f f f f f




Verified Answers) Plus Rationales 2026 Q f f f f f




&A | Instant Download Pdf
f f f f




1. What is the primary purpose of a wastewater treatment plant?
f f f f f f f f f f




A. Produce drinking water f f




B. Remove pollutants from wastewater before discharge
f f f f f




C. Generate electricity f




D. Irrigate crops f




Rationale: Wastewater treatment plants are designed to remove contaminant
f f f f f f f f




s and protect public health and the environment.
f f f f f f f




2. What is BOD a measure of in wastewater?
f f f f f f f




A. pH level f




B. Oxygen demand of biodegradable material
f f f f

, C. Nutrient concentration f




D. Temperature

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




ed oxygen required by microorganisms to break down organic material.
f f f f f f f f f




3. Which microorganism is most commonly responsible for secondary tr
f f f f f f f f




eatment in activated sludge systems?
f f f f




A. Algae
B. Viruses
C. Bacteria
D. Protozoa

Rationale: Bacteria metabolize organic matter in the activated sludge process,
f f f f f f f f f f




reducing BOD.
f




4. What is the typical range of pH for municipal wastewater?
f f f f f f f f f




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
f f f f f f f f f f f f f




microbial activity.
f




5. What is the main function of a grit chamber?
f f f f f f f f




A. Remove dissolved oxygen f f

, B. Settle out sand, gravel, and other heavy particles
f f f f f f f




C. Reduce nitrogen f




D. Neutralize pH f




Rationale: Grit chambers slow flow to allow heavy inorganic particles to settle.
f f f f f f f f f f f




6. Which of the following is a primary treatment process?
f f f f f f f f




A. Activated sludge f




B. Trickling filter f




C. Sedimentation
D. Aerated lagoon f




Rationale: Primary treatment removes settleable solids and some organic mat
f f f f f f f f f




erial via sedimentation.
f f




7. Nitrification in wastewater treatment converts: f f f f




A. Nitrate to ammonium f f




B. Nitrite to nitrogen gasf f f




C. Ammonium to nitrate f f




D. Organic nitrogen to protein f f f




Rationale: Nitrification is the biological conversion of ammonium to nitrate by
f f f f f f f f f f f




autotrophic bacteria.
f




8. Denitrification converts nitrate into: f f f




A. Ammonium
B. Nitrite

, C. Nitrogen gas f




D. Organic nitrogen f




Rationale: Denitrification is an anaerobic process converting nitrate into gaseo
f f f f f f f f f




us nitrogen, reducing nutrient load.
f f f f




9. What is the purpose of chlorination in wastewater treatment?
f f f f f f f f




A. Remove heavy metals f f




B. Increase pH f




C. Disinfect the effluent f f




D. Reduce BOD f




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




e discharge.
f




10. The normal dissolved oxygen (DO) range in activated sludge ae
f f f f f f f f f




ration tanks is:
f f




A. 0–1 mg/L f




B. 2–3 mg/L f




C. 1.5–2.5 mg/L f




D. 5–10 mg/L f




Rationale: Maintaining DO around 1.5–
f f f f




2.5 mg/L ensures effective aerobic microbial activity without wasting energy.
f f f f f f f f f




11. What is the typical sludge age for an extended aeration system?
f f f f f f f f f f




A. 1–2 days f




B. 3–5 days f