TEXAS WASTEWATER CLASS B EXAM 2026 – PRACTICE
QUESTIONS AND CORRECT ANSWERS WITH DETAILED
RATIONALES | LATEST UPDATED STUDY GUIDE | 100+ Q&A
| INSTANT DOWNLOAD PDF
1. Which Texas agency administers licensing for wastewater treatment
plant operators?
A. Texas Department of State Health Services
B. Texas Commission on Environmental Quality (TCEQ)
C. Texas Department of Transportation
D. Texas Water Development Board
Correct Answer: B. Texas Commission on Environmental Quality (TCEQ)
Rationale: TCEQ is responsible for occupational licensing of wastewater treatment plant and
collection system operators in Texas.
2. Which subject is specifically included in the TCEQ Class B wastewater
treatment operator examination criteria?
A. Marine biology
B. Process control
C. Highway construction
D. Agricultural economics
Correct Answer: B. Process control
Rationale: TCEQ identifies process control as a Class B examination category and expects
operators to use operational data and solids-control techniques to optimize treatment.
3. A wastewater discharge permit contains a maximum effluent
concentration for a pollutant. What should an operator do when monitoring
results exceed that limit?
A. Ignore one isolated result
B. Dilute the sample
,C. Evaluate the result as a potential permit violation and follow reporting requirements
D. Change the laboratory result
Correct Answer: C. Evaluate the result as a potential permit violation and follow reporting
requirements
Rationale: Class B operators are expected to determine whether wastewater flow and quality
records indicate violations of specific permit limits.
4. What is the primary purpose of preliminary treatment?
A. Remove dissolved nutrients
B. Remove large solids, debris, and grit that could damage downstream equipment
C. Produce biosolids for land application
D. Disinfect the final effluent
Correct Answer: B. Remove large solids, debris, and grit that could damage downstream
equipment
Rationale: Screening and grit removal protect pumps and downstream treatment units by
removing materials that can cause clogging, abrasion, or operational problems.
5. Which process is primarily biological?
A. Bar screening
B. Grit removal
C. Activated sludge
D. Flow measurement
Correct Answer: C. Activated sludge
Rationale: Activated sludge uses microorganisms to biologically remove organic matter and,
depending on the process configuration, nutrients from wastewater.
6. What is the main purpose of return activated sludge (RAS)?
A. Increase chlorine concentration
B. Return microorganisms from the secondary clarifier to the biological process
C. Remove grit from raw wastewater
D. Dispose of all activated sludge
,Correct Answer: B. Return microorganisms from the secondary clarifier to the biological
process
Rationale: RAS returns settled biological solids to the aeration basin, maintaining an appropriate
concentration of microorganisms for treatment.
7. A sudden increase in influent flow can cause what problem in a
secondary clarifier?
A. Increased detention time
B. Hydraulic overloading
C. Elimination of all solids
D. Reduced hydraulic loading
Correct Answer: B. Hydraulic overloading
Rationale: Excessive flow can increase surface overflow rates and reduce settling performance,
potentially causing solids to escape with the effluent.
8. What does MLSS generally represent?
A. Mixed liquor suspended solids
B. Maximum liquid sampling standard
C. Municipal laboratory safety system
D. Minimum loading sewage standard
Correct Answer: A. Mixed liquor suspended solids
Rationale: MLSS measures the concentration of suspended solids in the mixed liquor of an
activated-sludge system and is an important process-control parameter.
9. Why is dissolved oxygen monitored in an aeration basin?
A. To determine chlorine residual
B. To help ensure microorganisms have sufficient oxygen for aerobic treatment
C. To measure grit accumulation
D. To determine pipe diameter
Correct Answer: B. To help ensure microorganisms have sufficient oxygen for aerobic
treatment
, Rationale: Aerobic microorganisms require oxygen. Operators monitor DO to help maintain
suitable biological treatment conditions.
10. What is the main function of a secondary clarifier?
A. Remove grit
B. Separate biological solids from treated wastewater
C. Add chlorine
D. Increase influent BOD
Correct Answer: B. Separate biological solids from treated wastewater
Rationale: Secondary clarifiers allow biological floc to settle so clarified effluent can leave the
treatment process while settled solids can be returned or wasted.
11. What is BOD5 commonly used to measure?
A. Radioactivity
B. Oxygen demand associated with biodegradable organic matter
C. Chlorine residual only
D. Pipe friction
Correct Answer: B. Oxygen demand associated with biodegradable organic matter
Rationale: Five-day biochemical oxygen demand is an indicator of biodegradable organic
pollution and is an important wastewater-treatment parameter.
12. Why is an influent wastewater sample collected?
A. To determine characteristics entering the treatment process
B. To measure only final effluent chlorine
C. To determine employee attendance
D. To calculate pipe thickness
Correct Answer: A. To determine characteristics entering the treatment process
Rationale: Influent sampling provides information about the wastewater load and characteristics
entering the plant, helping operators evaluate treatment performance.
QUESTIONS AND CORRECT ANSWERS WITH DETAILED
RATIONALES | LATEST UPDATED STUDY GUIDE | 100+ Q&A
| INSTANT DOWNLOAD PDF
1. Which Texas agency administers licensing for wastewater treatment
plant operators?
A. Texas Department of State Health Services
B. Texas Commission on Environmental Quality (TCEQ)
C. Texas Department of Transportation
D. Texas Water Development Board
Correct Answer: B. Texas Commission on Environmental Quality (TCEQ)
Rationale: TCEQ is responsible for occupational licensing of wastewater treatment plant and
collection system operators in Texas.
2. Which subject is specifically included in the TCEQ Class B wastewater
treatment operator examination criteria?
A. Marine biology
B. Process control
C. Highway construction
D. Agricultural economics
Correct Answer: B. Process control
Rationale: TCEQ identifies process control as a Class B examination category and expects
operators to use operational data and solids-control techniques to optimize treatment.
3. A wastewater discharge permit contains a maximum effluent
concentration for a pollutant. What should an operator do when monitoring
results exceed that limit?
A. Ignore one isolated result
B. Dilute the sample
,C. Evaluate the result as a potential permit violation and follow reporting requirements
D. Change the laboratory result
Correct Answer: C. Evaluate the result as a potential permit violation and follow reporting
requirements
Rationale: Class B operators are expected to determine whether wastewater flow and quality
records indicate violations of specific permit limits.
4. What is the primary purpose of preliminary treatment?
A. Remove dissolved nutrients
B. Remove large solids, debris, and grit that could damage downstream equipment
C. Produce biosolids for land application
D. Disinfect the final effluent
Correct Answer: B. Remove large solids, debris, and grit that could damage downstream
equipment
Rationale: Screening and grit removal protect pumps and downstream treatment units by
removing materials that can cause clogging, abrasion, or operational problems.
5. Which process is primarily biological?
A. Bar screening
B. Grit removal
C. Activated sludge
D. Flow measurement
Correct Answer: C. Activated sludge
Rationale: Activated sludge uses microorganisms to biologically remove organic matter and,
depending on the process configuration, nutrients from wastewater.
6. What is the main purpose of return activated sludge (RAS)?
A. Increase chlorine concentration
B. Return microorganisms from the secondary clarifier to the biological process
C. Remove grit from raw wastewater
D. Dispose of all activated sludge
,Correct Answer: B. Return microorganisms from the secondary clarifier to the biological
process
Rationale: RAS returns settled biological solids to the aeration basin, maintaining an appropriate
concentration of microorganisms for treatment.
7. A sudden increase in influent flow can cause what problem in a
secondary clarifier?
A. Increased detention time
B. Hydraulic overloading
C. Elimination of all solids
D. Reduced hydraulic loading
Correct Answer: B. Hydraulic overloading
Rationale: Excessive flow can increase surface overflow rates and reduce settling performance,
potentially causing solids to escape with the effluent.
8. What does MLSS generally represent?
A. Mixed liquor suspended solids
B. Maximum liquid sampling standard
C. Municipal laboratory safety system
D. Minimum loading sewage standard
Correct Answer: A. Mixed liquor suspended solids
Rationale: MLSS measures the concentration of suspended solids in the mixed liquor of an
activated-sludge system and is an important process-control parameter.
9. Why is dissolved oxygen monitored in an aeration basin?
A. To determine chlorine residual
B. To help ensure microorganisms have sufficient oxygen for aerobic treatment
C. To measure grit accumulation
D. To determine pipe diameter
Correct Answer: B. To help ensure microorganisms have sufficient oxygen for aerobic
treatment
, Rationale: Aerobic microorganisms require oxygen. Operators monitor DO to help maintain
suitable biological treatment conditions.
10. What is the main function of a secondary clarifier?
A. Remove grit
B. Separate biological solids from treated wastewater
C. Add chlorine
D. Increase influent BOD
Correct Answer: B. Separate biological solids from treated wastewater
Rationale: Secondary clarifiers allow biological floc to settle so clarified effluent can leave the
treatment process while settled solids can be returned or wasted.
11. What is BOD5 commonly used to measure?
A. Radioactivity
B. Oxygen demand associated with biodegradable organic matter
C. Chlorine residual only
D. Pipe friction
Correct Answer: B. Oxygen demand associated with biodegradable organic matter
Rationale: Five-day biochemical oxygen demand is an indicator of biodegradable organic
pollution and is an important wastewater-treatment parameter.
12. Why is an influent wastewater sample collected?
A. To determine characteristics entering the treatment process
B. To measure only final effluent chlorine
C. To determine employee attendance
D. To calculate pipe thickness
Correct Answer: A. To determine characteristics entering the treatment process
Rationale: Influent sampling provides information about the wastewater load and characteristics
entering the plant, helping operators evaluate treatment performance.
