Exam Practice Questions And Correct

Texas Wastewater Operator Class B Exam Practice Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

• What is the primary purpose of a wastewater treatment plant?
• To produce drinking water
• To remove pollutants from wastewater before discharge
• To generate electricity
• To store wastewater

Rationale: The main goal of wastewater treatment is to remove harmful

pollutants and protect public health and the environment.

• Which microorganism is primarily responsible for breaking down

organic matter in activated sludge systems?

• Viruses 1 / 4

• Algae
• Protozoa
• Bacteria

Rationale: Bacteria are the main decomposers in biological treatment

processes, consuming organic matter.

3. The acronym BOD stands for:

• Biological Oxidation Demand
• Biochemical Organic Detergent
• Biochemical Oxygen Demand
• Basic Oxidation Dilution

Rationale: BOD measures the amount of oxygen required by

microorganisms to decompose organic matter in wastewater.

• 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.

• Which of the following is a common primary treatment method?
• Trickling filter
• Activated sludge 2 / 4

• Sedimentation
• Aerated lagoon

Rationale: Primary treatment removes settleable solids and floating

materials via sedimentation before biological treatment.

6. In wastewater terminology, TSS stands for:

• Total Soluble Salts
• Total Sulfate Solids
• Total Suspended Solids
• Total System Sludge

Rationale: TSS measures the solids suspended in wastewater, which need

to be removed during treatment.

• Which of the following is considered a secondary treatment process?
• Screening
• Activated sludge
• Grit removal
• Chlorination

Rationale: Secondary treatment focuses on removing dissolved and

colloidal organic matter biologically, such as with activated sludge.

• What is the main purpose of chlorination in wastewater treatment?
• Reduce BOD
• Disinfect the effluent 3 / 4

• Remove TSS
• Neutralize pH

Rationale: Chlorine is used to kill pathogenic microorganisms in the treated

wastewater before discharge.

• What is the function of an aeration tank?
• Remove grit
• Settle solids
• Provide oxygen to bacteria for organic matter breakdown
• Add chemicals to neutralize wastewater

Rationale: Aeration tanks supply oxygen to aerobic bacteria for

decomposing organic pollutants.

• What is the typical detention time for primary sedimentation

tanks?

• 5–10 minutes
• 30–60 minutes
• 1–3 hours
• 6–12 hours

Rationale: Primary sedimentation allows solids to settle; typical detention

time is 1–3 hours depending on flow.

• What is the main purpose of a grit chamber?
• Reduce BOD
• Remove organic solids
• / 4