TEXAS WASTEWATER CLASS B EXAM – 100
PRACTICE QUESTIONS AND CORRECT
ANSWERS WITH DETAILED RATIONALES | 2026
UPDATED STUDY GUIDE | INSTANT
DOWNLOAD PDF
1. What is the primary purpose of a wastewater discharge permit?
A. To establish employee salaries
B. To authorize and regulate the discharge of treated wastewater
C. To determine the plant's electrical rate
D. To determine the operator's license expiration date
Correct Answer: B
Rationale: A wastewater discharge permit establishes requirements and limits governing a
facility's authorized discharge. Operators must understand the permit and recognize when
monitoring results indicate a violation.
2. A Class B wastewater operator should be able to determine whether a
facility is violating its permit by evaluating:
A. Only the plant's daily electrical consumption
B. Flow and wastewater-quality data against permit requirements
C. Employee attendance records
D. Chemical purchase receipts only
Correct Answer: B
Rationale: TCEQ specifically identifies the ability to determine permit violations from
wastewater flow and quality records as a Class B competency.
3. Which treatment process uses microorganisms to remove biodegradable
organic matter from wastewater?
A. Biological treatment
B. Screening only
,C. Grit removal
D. Chlorine storage
Correct Answer: A
Rationale: Biological treatment uses microorganisms to metabolize biodegradable constituents
in wastewater. Activated sludge is an important biological treatment process covered in
wastewater operator training.
4. A wastewater plant receives an average flow of 2.0 MGD. Approximately
how many gallons does it receive in one day?
A. 200,000 gal
B. 500,000 gal
C. 2,000,000 gal
D. 20,000,000 gal
Correct Answer: C
Solution:
2.0 MGD = 2,000,000 gallons/day
5. A circular clarifier has a diameter of 40 ft. What is its approximate surface
area?
Use:
Area = πD²/4
A. 628 ft²
B. 1,257 ft²
C. 2,513 ft²
D. 5,026 ft²
Correct Answer: C
Solution:
Area = 3.14 × 40² ÷ 4
= 3.14 × 1,600 ÷ 4
= 1,256 ft²
,Wait—this gives approximately 1,257 ft², so:
Correct Answer: B
Exam tip: Always calculate rather than selecting an answer based on the apparent magnitude.
6. What is the main purpose of preliminary screening?
A. Remove large debris and protect downstream equipment
B. Increase dissolved oxygen
C. Disinfect final effluent
D. Stabilize biosolids
Correct Answer: A
Rationale: Screens remove large objects that could damage pumps and other downstream
equipment or interfere with treatment.
7. What is the primary purpose of grit removal?
A. Remove dissolved ammonia
B. Remove heavy inorganic particles such as sand and gravel
C. Destroy pathogens
D. Increase sludge moisture
Correct Answer: B
Rationale: Grit removal protects pumps and equipment and reduces unwanted accumulation of
inorganic solids.
8. In an activated-sludge system, dissolved oxygen is primarily required by:
A. Aerobic microorganisms
B. Bar screens
C. Grit particles
D. Chlorine molecules
Correct Answer: A
Rationale: Aerobic microorganisms require oxygen for biological oxidation and metabolism.
, 9. What is the purpose of secondary clarification in a conventional
activated-sludge process?
A. Remove large trash
B. Separate biological solids from treated wastewater
C. Add chlorine
D. Grind sludge
Correct Answer: B
Rationale: Secondary clarifiers allow biological floc to settle, separating activated sludge from
the clarified effluent.
10. A plant treats 1.5 MGD and applies 5 mg/L of chlorine. What is the
approximate chlorine dosage in pounds per day?
Use:
lb/day = MGD × mg/L × 8.34
A. 6.26 lb/day
B. 12.51 lb/day
C. 62.55 lb/day
D. 125.1 lb/day
Correct Answer: B
Solution:
1.5 × 5 × 8.34
= 62.55 lb/day
Therefore, the correct answer is actually:
Correct Answer: C
PRACTICE QUESTIONS AND CORRECT
ANSWERS WITH DETAILED RATIONALES | 2026
UPDATED STUDY GUIDE | INSTANT
DOWNLOAD PDF
1. What is the primary purpose of a wastewater discharge permit?
A. To establish employee salaries
B. To authorize and regulate the discharge of treated wastewater
C. To determine the plant's electrical rate
D. To determine the operator's license expiration date
Correct Answer: B
Rationale: A wastewater discharge permit establishes requirements and limits governing a
facility's authorized discharge. Operators must understand the permit and recognize when
monitoring results indicate a violation.
2. A Class B wastewater operator should be able to determine whether a
facility is violating its permit by evaluating:
A. Only the plant's daily electrical consumption
B. Flow and wastewater-quality data against permit requirements
C. Employee attendance records
D. Chemical purchase receipts only
Correct Answer: B
Rationale: TCEQ specifically identifies the ability to determine permit violations from
wastewater flow and quality records as a Class B competency.
3. Which treatment process uses microorganisms to remove biodegradable
organic matter from wastewater?
A. Biological treatment
B. Screening only
,C. Grit removal
D. Chlorine storage
Correct Answer: A
Rationale: Biological treatment uses microorganisms to metabolize biodegradable constituents
in wastewater. Activated sludge is an important biological treatment process covered in
wastewater operator training.
4. A wastewater plant receives an average flow of 2.0 MGD. Approximately
how many gallons does it receive in one day?
A. 200,000 gal
B. 500,000 gal
C. 2,000,000 gal
D. 20,000,000 gal
Correct Answer: C
Solution:
2.0 MGD = 2,000,000 gallons/day
5. A circular clarifier has a diameter of 40 ft. What is its approximate surface
area?
Use:
Area = πD²/4
A. 628 ft²
B. 1,257 ft²
C. 2,513 ft²
D. 5,026 ft²
Correct Answer: C
Solution:
Area = 3.14 × 40² ÷ 4
= 3.14 × 1,600 ÷ 4
= 1,256 ft²
,Wait—this gives approximately 1,257 ft², so:
Correct Answer: B
Exam tip: Always calculate rather than selecting an answer based on the apparent magnitude.
6. What is the main purpose of preliminary screening?
A. Remove large debris and protect downstream equipment
B. Increase dissolved oxygen
C. Disinfect final effluent
D. Stabilize biosolids
Correct Answer: A
Rationale: Screens remove large objects that could damage pumps and other downstream
equipment or interfere with treatment.
7. What is the primary purpose of grit removal?
A. Remove dissolved ammonia
B. Remove heavy inorganic particles such as sand and gravel
C. Destroy pathogens
D. Increase sludge moisture
Correct Answer: B
Rationale: Grit removal protects pumps and equipment and reduces unwanted accumulation of
inorganic solids.
8. In an activated-sludge system, dissolved oxygen is primarily required by:
A. Aerobic microorganisms
B. Bar screens
C. Grit particles
D. Chlorine molecules
Correct Answer: A
Rationale: Aerobic microorganisms require oxygen for biological oxidation and metabolism.
, 9. What is the purpose of secondary clarification in a conventional
activated-sludge process?
A. Remove large trash
B. Separate biological solids from treated wastewater
C. Add chlorine
D. Grind sludge
Correct Answer: B
Rationale: Secondary clarifiers allow biological floc to settle, separating activated sludge from
the clarified effluent.
10. A plant treats 1.5 MGD and applies 5 mg/L of chlorine. What is the
approximate chlorine dosage in pounds per day?
Use:
lb/day = MGD × mg/L × 8.34
A. 6.26 lb/day
B. 12.51 lb/day
C. 62.55 lb/day
D. 125.1 lb/day
Correct Answer: B
Solution:
1.5 × 5 × 8.34
= 62.55 lb/day
Therefore, the correct answer is actually:
Correct Answer: C
