NYC DEP Wastewater Treatment Plant
Operator Grade One Certification Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. A Grade One Wastewater Treatment Plant Operator certification
examination primarily evaluates an applicant’s understanding of which
combination of competencies?
A) Advanced hydraulic modeling, chemical engineering design, and
plant construction project management
B) Basic wastewater treatment processes, safety practices, simple
laboratory procedures, and elementary process control concepts
C) Electrical substation design, industrial power distribution, and
mechanical fabrication techniques
D) Environmental law enforcement procedures, court litigation
processes, and regulatory auditing systems
The Grade One examination focuses on foundational knowledge of
wastewater treatment including basic operations, safety, laboratory
sampling, and elementary treatment process understanding rather
than advanced engineering or legal enforcement topics.
,2. Which of the following best describes the purpose of preliminary
treatment in a wastewater facility?
A) To completely eliminate pathogens using ultraviolet radiation before
discharge
B) To remove large debris and grit that could damage downstream
equipment
C) To convert ammonia into nitrate using nitrifying bacteria
D) To stabilize sludge using anaerobic digestion only
Preliminary treatment is designed to protect equipment and improve
downstream efficiency by removing large solids, grit, and debris
before biological and chemical treatment processes.
3. In wastewater operations, what is the primary function of a bar
screen?
A) To measure dissolved oxygen levels in influent wastewater
B) To remove large floating and suspended debris from incoming flow
C) To disinfect wastewater using chlorine contact
D) To settle fine particles through gravity clarification
Bar screens act as a physical barrier that intercepts large solids such
as rags, plastics, and sticks, preventing damage to pumps and
downstream equipment.
4. Which unit process typically follows screening and grit removal in a
conventional treatment plant?
A) Disinfection
B) Primary sedimentation
C) UV irradiation
D) Effluent polishing filtration
Primary sedimentation follows preliminary treatment and allows
settleable solids and floatable materials to be removed through
gravity separation.
, 5. What is the main purpose of primary sedimentation tanks?
A) To promote biological oxidation of ammonia
B) To remove suspended solids through gravity settling
C) To destroy pathogens using ozone
D) To filter dissolved organic compounds
Primary sedimentation tanks reduce suspended solids and organic
load by allowing heavier particles to settle and lighter materials to
float.
6. Which parameter is most commonly used to indicate the amount of
oxygen required to break down organic matter in wastewater?
A) pH
B) BOD
C) Turbidity
D) Conductivity
Biochemical Oxygen Demand (BOD) measures the oxygen required by
microorganisms to decompose organic matter in wastewater.
7. In wastewater treatment safety practices, which hazard is most
commonly associated with confined spaces?
A) Exposure to extreme noise levels only
B) Oxygen deficiency and toxic gas accumulation
C) Excessive light intensity
D) High electromagnetic interference
Confined spaces in wastewater systems may contain hazardous gases
and low oxygen levels, posing serious life-threatening risks.
8. Which chemical is most commonly used for disinfection in wastewater
treatment plants?
A) Sodium chloride
B) Chlorine
C) Calcium carbonate
Operator Grade One Certification Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. A Grade One Wastewater Treatment Plant Operator certification
examination primarily evaluates an applicant’s understanding of which
combination of competencies?
A) Advanced hydraulic modeling, chemical engineering design, and
plant construction project management
B) Basic wastewater treatment processes, safety practices, simple
laboratory procedures, and elementary process control concepts
C) Electrical substation design, industrial power distribution, and
mechanical fabrication techniques
D) Environmental law enforcement procedures, court litigation
processes, and regulatory auditing systems
The Grade One examination focuses on foundational knowledge of
wastewater treatment including basic operations, safety, laboratory
sampling, and elementary treatment process understanding rather
than advanced engineering or legal enforcement topics.
,2. Which of the following best describes the purpose of preliminary
treatment in a wastewater facility?
A) To completely eliminate pathogens using ultraviolet radiation before
discharge
B) To remove large debris and grit that could damage downstream
equipment
C) To convert ammonia into nitrate using nitrifying bacteria
D) To stabilize sludge using anaerobic digestion only
Preliminary treatment is designed to protect equipment and improve
downstream efficiency by removing large solids, grit, and debris
before biological and chemical treatment processes.
3. In wastewater operations, what is the primary function of a bar
screen?
A) To measure dissolved oxygen levels in influent wastewater
B) To remove large floating and suspended debris from incoming flow
C) To disinfect wastewater using chlorine contact
D) To settle fine particles through gravity clarification
Bar screens act as a physical barrier that intercepts large solids such
as rags, plastics, and sticks, preventing damage to pumps and
downstream equipment.
4. Which unit process typically follows screening and grit removal in a
conventional treatment plant?
A) Disinfection
B) Primary sedimentation
C) UV irradiation
D) Effluent polishing filtration
Primary sedimentation follows preliminary treatment and allows
settleable solids and floatable materials to be removed through
gravity separation.
, 5. What is the main purpose of primary sedimentation tanks?
A) To promote biological oxidation of ammonia
B) To remove suspended solids through gravity settling
C) To destroy pathogens using ozone
D) To filter dissolved organic compounds
Primary sedimentation tanks reduce suspended solids and organic
load by allowing heavier particles to settle and lighter materials to
float.
6. Which parameter is most commonly used to indicate the amount of
oxygen required to break down organic matter in wastewater?
A) pH
B) BOD
C) Turbidity
D) Conductivity
Biochemical Oxygen Demand (BOD) measures the oxygen required by
microorganisms to decompose organic matter in wastewater.
7. In wastewater treatment safety practices, which hazard is most
commonly associated with confined spaces?
A) Exposure to extreme noise levels only
B) Oxygen deficiency and toxic gas accumulation
C) Excessive light intensity
D) High electromagnetic interference
Confined spaces in wastewater systems may contain hazardous gases
and low oxygen levels, posing serious life-threatening risks.
8. Which chemical is most commonly used for disinfection in wastewater
treatment plants?
A) Sodium chloride
B) Chlorine
C) Calcium carbonate
