Texas Wastewater Operator Class B Exam Practice Questions
And Correct Answers (Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a wastewater treatment plant?
A. To produce drinking water
B. To remove pollutants from wastewater before discharge
C. To generate electricity
D. To store wastewater
Rationale: The main goal of wastewater treatment is to remove harmful
pollutants and protect public health and the environment.
2. Which microorganism is primarily responsible for breaking down
organic matter in activated sludge systems?
A. Viruses
, B. Algae
C. Protozoa
D. Bacteria
Rationale: Bacteria are the main decomposers in biological treatment
processes, consuming organic matter.
3. The acronym BOD stands for:
A. Biological Oxidation Demand
B. Biochemical Organic Detergent
C. Biochemical Oxygen Demand
D. Basic Oxidation Dilution
Rationale: BOD measures the amount of oxygen required by
microorganisms to decompose organic matter in wastewater.
4. What is the ideal pH range for activated sludge processes?
A. 3.5–5.0
B. 6.0–6.5
C. 6.5–8.5
D. 9.0–10.5
Rationale: Microorganisms in activated sludge function best within a near-
neutral pH range of 6.5–8.5.
5. Which of the following is a common primary treatment method?
A. Trickling filter
B. Activated sludge
, C. Sedimentation
D. Aerated lagoon
Rationale: Primary treatment removes settleable solids and floating
materials via sedimentation before biological treatment.
6. In wastewater terminology, TSS stands for:
A. Total Soluble Salts
B. Total Sulfate Solids
C. Total Suspended Solids
D. Total System Sludge
Rationale: TSS measures the solids suspended in wastewater, which need
to be removed during treatment.
7. Which of the following is considered a secondary treatment process?
A. Screening
B. Activated sludge
C. Grit removal
D. Chlorination
Rationale: Secondary treatment focuses on removing dissolved and
colloidal organic matter biologically, such as with activated sludge.
8. What is the main purpose of chlorination in wastewater treatment?
A. Reduce BOD
B. Disinfect the effluent
, C. Remove TSS
D. Neutralize pH
Rationale: Chlorine is used to kill pathogenic microorganisms in the treated
wastewater before discharge.
9. What is the function of an aeration tank?
A. Remove grit
B. Settle solids
C. Provide oxygen to bacteria for organic matter breakdown
D. Add chemicals to neutralize wastewater
Rationale: Aeration tanks supply oxygen to aerobic bacteria for
decomposing organic pollutants.
10. What is the typical detention time for primary sedimentation
tanks?
A. 5–10 minutes
B. 30–60 minutes
C. 1–3 hours
D. 6–12 hours
Rationale: Primary sedimentation allows solids to settle; typical detention
time is 1–3 hours depending on flow.
11. What is the main purpose of a grit chamber?
A. Reduce BOD
B. Remove organic solids
And Correct Answers (Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. What is the primary purpose of a wastewater treatment plant?
A. To produce drinking water
B. To remove pollutants from wastewater before discharge
C. To generate electricity
D. To store wastewater
Rationale: The main goal of wastewater treatment is to remove harmful
pollutants and protect public health and the environment.
2. Which microorganism is primarily responsible for breaking down
organic matter in activated sludge systems?
A. Viruses
, B. Algae
C. Protozoa
D. Bacteria
Rationale: Bacteria are the main decomposers in biological treatment
processes, consuming organic matter.
3. The acronym BOD stands for:
A. Biological Oxidation Demand
B. Biochemical Organic Detergent
C. Biochemical Oxygen Demand
D. Basic Oxidation Dilution
Rationale: BOD measures the amount of oxygen required by
microorganisms to decompose organic matter in wastewater.
4. What is the ideal pH range for activated sludge processes?
A. 3.5–5.0
B. 6.0–6.5
C. 6.5–8.5
D. 9.0–10.5
Rationale: Microorganisms in activated sludge function best within a near-
neutral pH range of 6.5–8.5.
5. Which of the following is a common primary treatment method?
A. Trickling filter
B. Activated sludge
, C. Sedimentation
D. Aerated lagoon
Rationale: Primary treatment removes settleable solids and floating
materials via sedimentation before biological treatment.
6. In wastewater terminology, TSS stands for:
A. Total Soluble Salts
B. Total Sulfate Solids
C. Total Suspended Solids
D. Total System Sludge
Rationale: TSS measures the solids suspended in wastewater, which need
to be removed during treatment.
7. Which of the following is considered a secondary treatment process?
A. Screening
B. Activated sludge
C. Grit removal
D. Chlorination
Rationale: Secondary treatment focuses on removing dissolved and
colloidal organic matter biologically, such as with activated sludge.
8. What is the main purpose of chlorination in wastewater treatment?
A. Reduce BOD
B. Disinfect the effluent
, C. Remove TSS
D. Neutralize pH
Rationale: Chlorine is used to kill pathogenic microorganisms in the treated
wastewater before discharge.
9. What is the function of an aeration tank?
A. Remove grit
B. Settle solids
C. Provide oxygen to bacteria for organic matter breakdown
D. Add chemicals to neutralize wastewater
Rationale: Aeration tanks supply oxygen to aerobic bacteria for
decomposing organic pollutants.
10. What is the typical detention time for primary sedimentation
tanks?
A. 5–10 minutes
B. 30–60 minutes
C. 1–3 hours
D. 6–12 hours
Rationale: Primary sedimentation allows solids to settle; typical detention
time is 1–3 hours depending on flow.
11. What is the main purpose of a grit chamber?
A. Reduce BOD
B. Remove organic solids
