NYC DEP Wastewater Treatment Plant Operator Exam
Fundamentals Questions WITH CORRECT ANSWERS
(VERIFED ANSWERS) PLUS RATIONALES 2026 Q&A
|INSTANT DOWNLOAD PDF
1. What is the primary purpose of a wastewater treatment
plant?
A. To increase water hardness
B. To remove pollutants and contaminants from wastewater
C. To add chemicals to drinking water
D. To generate electricity from wastewater
Correct answer: B
Rationale: Wastewater treatment plants are designed to
remove physical, chemical, and biological pollutants to protect
human health and the environment.
2. Which process is considered primary treatment in
wastewater treatment?
A. Biological digestion
B. Sedimentation of solids
C. Chlorination
D. Aeration
,Correct answer: B
Rationale: Primary treatment involves the physical removal of
large solids and sedimentation to reduce suspended solids.
3. What is the function of aeration in secondary treatment?
A. To remove heavy metals
B. To provide oxygen for microorganisms
C. To settle sludge
D. To remove chlorine
Correct answer: B
Rationale: Aeration supplies oxygen to microorganisms that
biologically degrade organic matter in wastewater.
4. Which of the following are common indicators of
wastewater strength?
A. BOD
B. COD
C. pH
D. Color
Correct answers: A, B
Rationale: BOD (Biochemical Oxygen Demand) and COD
(Chemical Oxygen Demand) measure the organic pollutant load
and the strength of wastewater.
,5. Which type of microorganism is primarily responsible for
breaking down organic matter in activated sludge?
A. Viruses
B. Bacteria
C. Protozoa
D. Fungi
Correct answer: B
Rationale: Bacteria are the main microorganisms that
metabolize organic pollutants in wastewater treatment.
6. What is the main purpose of sludge digestion?
A. To increase sludge volume
B. To stabilize sludge and reduce pathogens
C. To remove chlorine
D. To aerate water
Correct answer: B
Rationale: Sludge digestion reduces organic matter, stabilizes
solids, and minimizes pathogens before disposal.
7. Which parameter is used to monitor oxygen demand in
wastewater?
A. pH
B. BOD
C. Conductivity
D. Turbidity
, Correct answer: B
Rationale: BOD measures the amount of oxygen required by
microorganisms to decompose organic matter.
8. Which of the following chemicals is commonly used for
disinfection in wastewater?
A. Sodium hypochlorite
B. Ferric chloride
C. Alum
D. Ammonia
Correct answer: A
Rationale: Sodium hypochlorite (bleach) is widely used to
disinfect treated wastewater by killing pathogens.
9. What is the purpose of a grit chamber?
A. Remove oils and grease
B. Remove heavy inorganic solids like sand and gravel
C. Increase oxygen levels
D. Measure BOD
Correct answer: B
Rationale: Grit chambers remove heavy inorganic materials
that can damage pumps and downstream equipment.
Fundamentals Questions WITH CORRECT ANSWERS
(VERIFED ANSWERS) PLUS RATIONALES 2026 Q&A
|INSTANT DOWNLOAD PDF
1. What is the primary purpose of a wastewater treatment
plant?
A. To increase water hardness
B. To remove pollutants and contaminants from wastewater
C. To add chemicals to drinking water
D. To generate electricity from wastewater
Correct answer: B
Rationale: Wastewater treatment plants are designed to
remove physical, chemical, and biological pollutants to protect
human health and the environment.
2. Which process is considered primary treatment in
wastewater treatment?
A. Biological digestion
B. Sedimentation of solids
C. Chlorination
D. Aeration
,Correct answer: B
Rationale: Primary treatment involves the physical removal of
large solids and sedimentation to reduce suspended solids.
3. What is the function of aeration in secondary treatment?
A. To remove heavy metals
B. To provide oxygen for microorganisms
C. To settle sludge
D. To remove chlorine
Correct answer: B
Rationale: Aeration supplies oxygen to microorganisms that
biologically degrade organic matter in wastewater.
4. Which of the following are common indicators of
wastewater strength?
A. BOD
B. COD
C. pH
D. Color
Correct answers: A, B
Rationale: BOD (Biochemical Oxygen Demand) and COD
(Chemical Oxygen Demand) measure the organic pollutant load
and the strength of wastewater.
,5. Which type of microorganism is primarily responsible for
breaking down organic matter in activated sludge?
A. Viruses
B. Bacteria
C. Protozoa
D. Fungi
Correct answer: B
Rationale: Bacteria are the main microorganisms that
metabolize organic pollutants in wastewater treatment.
6. What is the main purpose of sludge digestion?
A. To increase sludge volume
B. To stabilize sludge and reduce pathogens
C. To remove chlorine
D. To aerate water
Correct answer: B
Rationale: Sludge digestion reduces organic matter, stabilizes
solids, and minimizes pathogens before disposal.
7. Which parameter is used to monitor oxygen demand in
wastewater?
A. pH
B. BOD
C. Conductivity
D. Turbidity
, Correct answer: B
Rationale: BOD measures the amount of oxygen required by
microorganisms to decompose organic matter.
8. Which of the following chemicals is commonly used for
disinfection in wastewater?
A. Sodium hypochlorite
B. Ferric chloride
C. Alum
D. Ammonia
Correct answer: A
Rationale: Sodium hypochlorite (bleach) is widely used to
disinfect treated wastewater by killing pathogens.
9. What is the purpose of a grit chamber?
A. Remove oils and grease
B. Remove heavy inorganic solids like sand and gravel
C. Increase oxygen levels
D. Measure BOD
Correct answer: B
Rationale: Grit chambers remove heavy inorganic materials
that can damage pumps and downstream equipment.
