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Virginia Wastewater Operator Class 2 License
Exam QUESTIONS AND VERIFIED ANSWERS WITH
RATIONALES JUST RELEASED
Virginia Wastewater Operator Class 2 License Exam - Practice Questions
10 Most Tested Exam Coverage Areas
1. Preliminary Treatment - Bar screens, grit removal, flow equalization
2. Primary Treatment - Sedimentation, clarifier operation, scum removal
3. Secondary Treatment (Activated Sludge) - Aeration, MLSS, F/M ratio, SRT, MCRT
4. Secondary Treatment (Trickling Filters) - Recirculation, media, biological growth
5. Sludge Treatment & Disposal - Digestion (aerobic/anaerobic), thickening, dewatering
6. Disinfection - Chlorination, dechlorination, UV, ozone
7. Laboratory & Process Control - BOD, COD, TSS, DO, SVI, microscopic exams
8. Safety & Confined Space - LOTO, PPE, gas monitoring, H2S, chlorine safety
9. Regulations & Reporting - VPDES permits, DEQ, NPDES, DMRs, DPOR CPE hours
10. Nutrient Removal - Nitrification, denitrification, biological phosphorus removal
Question 1: Which of the following wastewater treatment processes uses microorganisms attached to a
solid media surface to break down organic matter and is considered a form of biological treatment?
A) Activated sludge process
B) Trickling filter process
C) Rotating biological contactor
D) Sequencing batch reactor
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Answer: B) Trickling filter process
Rationale: Trickling filters use a solid media such as rocks or plastic where microorganisms attach and
form a biological film that consumes organic matter from wastewater flowing over the surface .
Question 2: When an operator observes that the sludge in the secondary clarifier is rising to the surface
in large clumps, this condition is most likely caused by which of the following operational problems in
the aeration tank?
A) High dissolved oxygen levels
B) Denitrification occurring in the clarifier
C) Excessive return activated sludge flow
D) Low influent BOD concentration
Answer: B) Denitrification occurring in the clarifier
Rationale: Denitrification produces nitrogen gas that attaches to sludge particles and floats them to the
surface, a condition known as sludge rising .
Question 3: The Virginia Department of Environmental Quality is the state agency responsible for issuing
which type of permit that regulates the discharge of pollutants from wastewater treatment facilities into
state waters?
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A) VPDES permit
B) Air quality permit
C) Solid waste permit
D) Underground injection permit
Answer: A) VPDES permit
Rationale: The Virginia Department of Environmental Quality administers the Virginia Pollutant
Discharge Elimination System (VPDES) permitting program, which regulates all wastewater discharges in
the Commonwealth .
Question 4: What is the primary purpose of adding chemicals such as alum or ferric chloride to the
wastewater treatment process during phosphorus removal operations?
A) To increase the pH of the effluent
B) To precipitate phosphorus into a solid form
C) To oxidize organic matter more quickly
D) To kill harmful bacteria and viruses
Answer: B) To precipitate phosphorus into a solid form
Rationale: Chemical precipitation uses metal salts like alum to react with phosphorus and form insoluble
compounds that can be removed through sedimentation .
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Question 5: In the activated sludge process, the food-to-microorganism ratio is an important control
parameter that is calculated using which of the following sets of measurements?
A) Influent BOD and mixed liquor suspended solids
B) Effluent TSS and return sludge flow rate
C) Influent flow rate and clarifier depth
D) Aeration tank volume and sludge age
Answer: A) Influent BOD and mixed liquor suspended solids
Rationale: The F/M ratio compares the amount of food (BOD) entering the system to the mass of
microorganisms (MLSS) available to consume it .
Question 6: Which of the following safety procedures is designed to prevent the unexpected startup of
machinery or release of stored energy during maintenance activities at a wastewater treatment plant?
A) Confined space entry permit
B) Lockout/Tagout procedure
C) Hazard communication program
D) Personal protective equipment use
Virginia Wastewater Operator Class 2 License
Exam QUESTIONS AND VERIFIED ANSWERS WITH
RATIONALES JUST RELEASED
Virginia Wastewater Operator Class 2 License Exam - Practice Questions
10 Most Tested Exam Coverage Areas
1. Preliminary Treatment - Bar screens, grit removal, flow equalization
2. Primary Treatment - Sedimentation, clarifier operation, scum removal
3. Secondary Treatment (Activated Sludge) - Aeration, MLSS, F/M ratio, SRT, MCRT
4. Secondary Treatment (Trickling Filters) - Recirculation, media, biological growth
5. Sludge Treatment & Disposal - Digestion (aerobic/anaerobic), thickening, dewatering
6. Disinfection - Chlorination, dechlorination, UV, ozone
7. Laboratory & Process Control - BOD, COD, TSS, DO, SVI, microscopic exams
8. Safety & Confined Space - LOTO, PPE, gas monitoring, H2S, chlorine safety
9. Regulations & Reporting - VPDES permits, DEQ, NPDES, DMRs, DPOR CPE hours
10. Nutrient Removal - Nitrification, denitrification, biological phosphorus removal
Question 1: Which of the following wastewater treatment processes uses microorganisms attached to a
solid media surface to break down organic matter and is considered a form of biological treatment?
A) Activated sludge process
B) Trickling filter process
C) Rotating biological contactor
D) Sequencing batch reactor
, Page 2 of 146
Answer: B) Trickling filter process
Rationale: Trickling filters use a solid media such as rocks or plastic where microorganisms attach and
form a biological film that consumes organic matter from wastewater flowing over the surface .
Question 2: When an operator observes that the sludge in the secondary clarifier is rising to the surface
in large clumps, this condition is most likely caused by which of the following operational problems in
the aeration tank?
A) High dissolved oxygen levels
B) Denitrification occurring in the clarifier
C) Excessive return activated sludge flow
D) Low influent BOD concentration
Answer: B) Denitrification occurring in the clarifier
Rationale: Denitrification produces nitrogen gas that attaches to sludge particles and floats them to the
surface, a condition known as sludge rising .
Question 3: The Virginia Department of Environmental Quality is the state agency responsible for issuing
which type of permit that regulates the discharge of pollutants from wastewater treatment facilities into
state waters?
, Page 3 of 146
A) VPDES permit
B) Air quality permit
C) Solid waste permit
D) Underground injection permit
Answer: A) VPDES permit
Rationale: The Virginia Department of Environmental Quality administers the Virginia Pollutant
Discharge Elimination System (VPDES) permitting program, which regulates all wastewater discharges in
the Commonwealth .
Question 4: What is the primary purpose of adding chemicals such as alum or ferric chloride to the
wastewater treatment process during phosphorus removal operations?
A) To increase the pH of the effluent
B) To precipitate phosphorus into a solid form
C) To oxidize organic matter more quickly
D) To kill harmful bacteria and viruses
Answer: B) To precipitate phosphorus into a solid form
Rationale: Chemical precipitation uses metal salts like alum to react with phosphorus and form insoluble
compounds that can be removed through sedimentation .
, Page 4 of 146
Question 5: In the activated sludge process, the food-to-microorganism ratio is an important control
parameter that is calculated using which of the following sets of measurements?
A) Influent BOD and mixed liquor suspended solids
B) Effluent TSS and return sludge flow rate
C) Influent flow rate and clarifier depth
D) Aeration tank volume and sludge age
Answer: A) Influent BOD and mixed liquor suspended solids
Rationale: The F/M ratio compares the amount of food (BOD) entering the system to the mass of
microorganisms (MLSS) available to consume it .
Question 6: Which of the following safety procedures is designed to prevent the unexpected startup of
machinery or release of stored energy during maintenance activities at a wastewater treatment plant?
A) Confined space entry permit
B) Lockout/Tagout procedure
C) Hazard communication program
D) Personal protective equipment use
