Texas Wastewater Class D | Questions with
100% Correct Answers | Verified | Latest
Update 2025
1. What is the primary purpose of wastewater treatment?
A. To generate electricity
B. To provide drinking water
C. To remove contaminants from water before discharge
D. To increase water temperature
Correct answer: C. Wastewater treatment aims to remove physical, chemical,
and biological contaminants to protect public health and the environment.
2. What is the most common type of wastewater treatment plant in Texas?
A. Tertiary treatment plant
B. Activated sludge plant
C. Trickling filter plant
D. Membrane bioreactor plant
Correct answer: B. Activated sludge systems are widely used due to their
efficiency and flexibility.
,3. Which of the following is a secondary treatment process?
A. Screening
B. Grit removal
C. Aeration
D. Chlorination
Correct answer: C. Aeration is part of secondary (biological) treatment where
microorganisms break down organic matter.
4. What is the typical pH range for treated wastewater discharge?
A. 3.0–5.0
B. 6.0–7.0
C. 6.0–9.0
D. 10.0–12.0
Correct answer: C. Most permits require the pH of effluent to be between 6.0
and 9.0.
5. What does BOD stand for?
A. Biological Odor Detection
B. Biochemical Oxide Demand
C. Biochemical Oxygen Demand
D. Basic Oxygen Dispersion
Correct answer: C. BOD measures the amount of oxygen microorganisms need
to decompose organic matter.
,6. What is the purpose of a bar screen in wastewater treatment?
A. Add chlorine
B. Remove large solids
C. Aerate water
D. Adjust pH
Correct answer: B. Bar screens remove rags, sticks, and other large debris from
incoming wastewater.
7. What does TCEQ stand for?
A. Texas Commission on Energy Quality
B. Texas Commission on Environmental Quality
C. Texas Committee for Environmental Quotas
D. Texas Council on Equipment Quality
Correct answer: B. TCEQ regulates wastewater treatment and environmental
quality in Texas.
8. What is the main function of clarifiers?
A. Disinfect water
B. Settle out solids
C. Remove odors
D. Add oxygen
Correct answer: B. Clarifiers allow solids to settle out of the water for removal.
, 9. Why is it important to control the flow rate in a treatment plant?
A. To increase chemical use
B. To avoid overloading the system
C. To raise sludge temperature
D. To decrease BOD
Correct answer: B. Flow control prevents hydraulic or organic overloads that can
upset the treatment process.
10. What is sludge?
A. Clean drinking water
B. Solid waste material removed from wastewater
C. Oxygen-rich water
D. Disinfected effluent
Correct answer: B. Sludge is the semi-solid waste collected during treatment.
11. What is the purpose of disinfection in wastewater treatment?
A. Remove sludge
B. Adjust pH
C. Remove solids
D. Kill disease-causing organisms
Correct answer: D. Disinfection destroys pathogens before effluent is released to
the environment.
100% Correct Answers | Verified | Latest
Update 2025
1. What is the primary purpose of wastewater treatment?
A. To generate electricity
B. To provide drinking water
C. To remove contaminants from water before discharge
D. To increase water temperature
Correct answer: C. Wastewater treatment aims to remove physical, chemical,
and biological contaminants to protect public health and the environment.
2. What is the most common type of wastewater treatment plant in Texas?
A. Tertiary treatment plant
B. Activated sludge plant
C. Trickling filter plant
D. Membrane bioreactor plant
Correct answer: B. Activated sludge systems are widely used due to their
efficiency and flexibility.
,3. Which of the following is a secondary treatment process?
A. Screening
B. Grit removal
C. Aeration
D. Chlorination
Correct answer: C. Aeration is part of secondary (biological) treatment where
microorganisms break down organic matter.
4. What is the typical pH range for treated wastewater discharge?
A. 3.0–5.0
B. 6.0–7.0
C. 6.0–9.0
D. 10.0–12.0
Correct answer: C. Most permits require the pH of effluent to be between 6.0
and 9.0.
5. What does BOD stand for?
A. Biological Odor Detection
B. Biochemical Oxide Demand
C. Biochemical Oxygen Demand
D. Basic Oxygen Dispersion
Correct answer: C. BOD measures the amount of oxygen microorganisms need
to decompose organic matter.
,6. What is the purpose of a bar screen in wastewater treatment?
A. Add chlorine
B. Remove large solids
C. Aerate water
D. Adjust pH
Correct answer: B. Bar screens remove rags, sticks, and other large debris from
incoming wastewater.
7. What does TCEQ stand for?
A. Texas Commission on Energy Quality
B. Texas Commission on Environmental Quality
C. Texas Committee for Environmental Quotas
D. Texas Council on Equipment Quality
Correct answer: B. TCEQ regulates wastewater treatment and environmental
quality in Texas.
8. What is the main function of clarifiers?
A. Disinfect water
B. Settle out solids
C. Remove odors
D. Add oxygen
Correct answer: B. Clarifiers allow solids to settle out of the water for removal.
, 9. Why is it important to control the flow rate in a treatment plant?
A. To increase chemical use
B. To avoid overloading the system
C. To raise sludge temperature
D. To decrease BOD
Correct answer: B. Flow control prevents hydraulic or organic overloads that can
upset the treatment process.
10. What is sludge?
A. Clean drinking water
B. Solid waste material removed from wastewater
C. Oxygen-rich water
D. Disinfected effluent
Correct answer: B. Sludge is the semi-solid waste collected during treatment.
11. What is the purpose of disinfection in wastewater treatment?
A. Remove sludge
B. Adjust pH
C. Remove solids
D. Kill disease-causing organisms
Correct answer: D. Disinfection destroys pathogens before effluent is released to
the environment.
