SWRCB – WASTEWATER TREATMENT PLANT OPERATOR
CERTIFICATION EXAM GRADE I– QUESTIONS AND ANSWERS |
VERIFIED AND WELL DETAILED ANSWERS | PLUS RATIONALES |
DOWNLOAD AND PASS | LATEST EXAM UPDATE 2026/2027 –
QUESTIONS AND ANSWERS | VERIFIED AND WELL DETAILED
ANSWERS | PLUS RATIONALES | GUARANTEED PASS | LATEST
EXAM UPDATE
CORE DOMAINS
1. Wastewater Characteristics and Sampling
2. Preliminary and Primary Treatment Operations
3. Anaerobic Sludge Digestion
4. Disinfection and Effluent Quality
5. Stabilization Ponds and Lagoon Systems
6. Safety Practices and Confined Space Entry
7. Regulatory Compliance and Operator Certification
8. Mathematical Calculations and Process Control
9. Basic Laboratory Analysis and Process Monitoring
10. Professional Ethics and Decision-Making
INTRODUCTION
The SWRCB Wastewater Treatment Plant Operator Certification Grade I examination assesses
foundational competency for entry-level operators in California. This comprehensive assessment
evaluates knowledge of basic treatment processes, sampling and analysis procedures, safety protocols,
and state regulations governing wastewater operations. The exam employs multiple-choice and scenario-
based questions designed to test real-world application of technical concepts. Candidates must
demonstrate understanding of preliminary and primary treatment, anaerobic digestion, disinfection,
stabilization ponds, and mathematical calculations essential for process control. Emphasis is placed on
professional decision-making, regulatory compliance, and the practical skills necessary to protect public
health and the environment through effective wastewater treatment operations.
SECTION ONE – QUESTIONS 1–100
,Question 1
What is the primary purpose of a wastewater treatment plant?
A. To increase the temperature of wastewater
B. To produce drinking water directly from raw sewage
C. To remove pollutants from wastewater before discharge or reuse
D. To increase the flow entering the collection system
🟢 Correct answer: C
🔴 Explanation: The primary purpose of wastewater treatment is to remove physical, chemical, and
biological pollutants so treated effluent can be discharged or beneficially reused without causing
unacceptable impacts to public health or the environment.
Question 2
Which treatment process is primarily used to remove large debris such as rags, sticks, and plastics?
A. Chlorination
B. Screening
C. Activated sludge
D. Secondary clarification
🟢 Correct answer: B
🔴 Explanation: Screens are installed near the beginning of the treatment process to physically
remove large materials that could damage pumps, clog pipes, or interfere with downstream treatment
equipment.
Question 3
What is the main purpose of a comminutor?
A. To disinfect wastewater
B. To reduce the size of solids in wastewater
C. To increase dissolved oxygen
D. To remove dissolved ammonia
🟢 Correct answer: B
🔴 Explanation: Comminutors grind or shred solids into smaller particles to prevent clogging of
downstream equipment and facilitate subsequent treatment processes.
Question 4
What is the primary function of a grit chamber?
A. Remove pathogens
,B. Remove sand, gravel, and grit
C. Aerate wastewater
D. Neutralize pH
🟢 Correct answer: B
🔴 Explanation: Grit chambers remove heavy inorganic particles that could damage pumps and
downstream equipment or accumulate in treatment units.
Question 5
What is the primary function of a primary clarifier?
A. Add chlorine to wastewater
B. Remove settleable and floatable solids
C. Increase wastewater temperature
D. Produce oxygen biologically
🟢 Correct answer: B
🔴 Explanation: Primary clarification allows heavier suspended solids to settle as primary sludge while
lighter materials such as grease and scum float and can be removed from the surface.
Question 6
What does BOD stand for?
A. Biological Oxygen Demand
B. Bacterial Oxidation Density
C. Biochemical Organic Discharge
D. Biological Oxidation Difference
🟢 Correct answer: A
🔴 Explanation: BOD refers to the amount of oxygen microorganisms require to biologically stabilize
biodegradable organic matter under specified test conditions and is an important indicator of organic
pollution.
Question 7
What does TSS measure in wastewater?
A. Total soluble salts
B. Total Suspended Solids
C. Treatment Sludge Solution
D. Total Soluble Solids
🟢 Correct answer: B
, 🔴 Explanation: TSS measures the amount of particles suspended in wastewater that can be removed
by filtration and is a key indicator of treatment performance.
Question 8
What is the typical suspended solids removal efficiency of a primary clarifier?
A. 10–20%
B. 40–60%
C. 70–80%
D. 90–95%
🟢 Correct answer: B
🔴 Explanation: Primary clarifiers typically remove 40–60% of suspended solids and 25–35% of BOD
through gravity settling and flotation.
Question 9
What is the primary purpose of disinfection in wastewater treatment?
A. Remove nutrients
B. Destroy pathogenic organisms
C. Increase dissolved oxygen
D. Remove heavy metals
🟢 Correct answer: B
🔴 Explanation: Disinfection reduces pathogenic microorganisms to levels that protect public health
and the environment before effluent discharge or reuse.
Question 10
Which chemical is commonly used for wastewater disinfection?
A. Sodium hydroxide
B. Chlorine
C. Sulfuric acid
D. Ferric chloride
🟢 Correct answer: B
🔴 Explanation: Chlorine is widely used for disinfection because it effectively kills bacteria and viruses
and provides a measurable residual for process control.
CERTIFICATION EXAM GRADE I– QUESTIONS AND ANSWERS |
VERIFIED AND WELL DETAILED ANSWERS | PLUS RATIONALES |
DOWNLOAD AND PASS | LATEST EXAM UPDATE 2026/2027 –
QUESTIONS AND ANSWERS | VERIFIED AND WELL DETAILED
ANSWERS | PLUS RATIONALES | GUARANTEED PASS | LATEST
EXAM UPDATE
CORE DOMAINS
1. Wastewater Characteristics and Sampling
2. Preliminary and Primary Treatment Operations
3. Anaerobic Sludge Digestion
4. Disinfection and Effluent Quality
5. Stabilization Ponds and Lagoon Systems
6. Safety Practices and Confined Space Entry
7. Regulatory Compliance and Operator Certification
8. Mathematical Calculations and Process Control
9. Basic Laboratory Analysis and Process Monitoring
10. Professional Ethics and Decision-Making
INTRODUCTION
The SWRCB Wastewater Treatment Plant Operator Certification Grade I examination assesses
foundational competency for entry-level operators in California. This comprehensive assessment
evaluates knowledge of basic treatment processes, sampling and analysis procedures, safety protocols,
and state regulations governing wastewater operations. The exam employs multiple-choice and scenario-
based questions designed to test real-world application of technical concepts. Candidates must
demonstrate understanding of preliminary and primary treatment, anaerobic digestion, disinfection,
stabilization ponds, and mathematical calculations essential for process control. Emphasis is placed on
professional decision-making, regulatory compliance, and the practical skills necessary to protect public
health and the environment through effective wastewater treatment operations.
SECTION ONE – QUESTIONS 1–100
,Question 1
What is the primary purpose of a wastewater treatment plant?
A. To increase the temperature of wastewater
B. To produce drinking water directly from raw sewage
C. To remove pollutants from wastewater before discharge or reuse
D. To increase the flow entering the collection system
🟢 Correct answer: C
🔴 Explanation: The primary purpose of wastewater treatment is to remove physical, chemical, and
biological pollutants so treated effluent can be discharged or beneficially reused without causing
unacceptable impacts to public health or the environment.
Question 2
Which treatment process is primarily used to remove large debris such as rags, sticks, and plastics?
A. Chlorination
B. Screening
C. Activated sludge
D. Secondary clarification
🟢 Correct answer: B
🔴 Explanation: Screens are installed near the beginning of the treatment process to physically
remove large materials that could damage pumps, clog pipes, or interfere with downstream treatment
equipment.
Question 3
What is the main purpose of a comminutor?
A. To disinfect wastewater
B. To reduce the size of solids in wastewater
C. To increase dissolved oxygen
D. To remove dissolved ammonia
🟢 Correct answer: B
🔴 Explanation: Comminutors grind or shred solids into smaller particles to prevent clogging of
downstream equipment and facilitate subsequent treatment processes.
Question 4
What is the primary function of a grit chamber?
A. Remove pathogens
,B. Remove sand, gravel, and grit
C. Aerate wastewater
D. Neutralize pH
🟢 Correct answer: B
🔴 Explanation: Grit chambers remove heavy inorganic particles that could damage pumps and
downstream equipment or accumulate in treatment units.
Question 5
What is the primary function of a primary clarifier?
A. Add chlorine to wastewater
B. Remove settleable and floatable solids
C. Increase wastewater temperature
D. Produce oxygen biologically
🟢 Correct answer: B
🔴 Explanation: Primary clarification allows heavier suspended solids to settle as primary sludge while
lighter materials such as grease and scum float and can be removed from the surface.
Question 6
What does BOD stand for?
A. Biological Oxygen Demand
B. Bacterial Oxidation Density
C. Biochemical Organic Discharge
D. Biological Oxidation Difference
🟢 Correct answer: A
🔴 Explanation: BOD refers to the amount of oxygen microorganisms require to biologically stabilize
biodegradable organic matter under specified test conditions and is an important indicator of organic
pollution.
Question 7
What does TSS measure in wastewater?
A. Total soluble salts
B. Total Suspended Solids
C. Treatment Sludge Solution
D. Total Soluble Solids
🟢 Correct answer: B
, 🔴 Explanation: TSS measures the amount of particles suspended in wastewater that can be removed
by filtration and is a key indicator of treatment performance.
Question 8
What is the typical suspended solids removal efficiency of a primary clarifier?
A. 10–20%
B. 40–60%
C. 70–80%
D. 90–95%
🟢 Correct answer: B
🔴 Explanation: Primary clarifiers typically remove 40–60% of suspended solids and 25–35% of BOD
through gravity settling and flotation.
Question 9
What is the primary purpose of disinfection in wastewater treatment?
A. Remove nutrients
B. Destroy pathogenic organisms
C. Increase dissolved oxygen
D. Remove heavy metals
🟢 Correct answer: B
🔴 Explanation: Disinfection reduces pathogenic microorganisms to levels that protect public health
and the environment before effluent discharge or reuse.
Question 10
Which chemical is commonly used for wastewater disinfection?
A. Sodium hydroxide
B. Chlorine
C. Sulfuric acid
D. Ferric chloride
🟢 Correct answer: B
🔴 Explanation: Chlorine is widely used for disinfection because it effectively kills bacteria and viruses
and provides a measurable residual for process control.
