NYC Environmental Engineer — Exam
6056 Practice Test Questions and
Correct Answers (Verified Answers) Plus
Rationales 2025|2026 Q&A | Instant
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1. Which parameter is most directly used to indicate the amount of oxygen
required to biologically degrade biodegradable organic matter in wastewater?
A. Total dissolved solids
B. Chemical oxygen demand
C. Biochemical oxygen demand
D. Alkalinity
Correct Answer: C. Biochemical oxygen demand
Biochemical oxygen demand (BOD) measures the amount of dissolved oxygen
microorganisms require to biologically decompose biodegradable organic material
in water. It is a fundamental parameter for evaluating wastewater strength and
treatment performance.
2. What is the primary purpose of a sedimentation basin in conventional
wastewater treatment?
A. Remove settleable suspended solids
B. Increase dissolved oxygen
C. Destroy dissolved pathogens through ultraviolet radiation
D. Convert ammonia directly to nitrogen gas
Correct Answer: A. Remove settleable suspended solids
Sedimentation allows suspended particles that are denser than water to settle
under relatively quiescent conditions. Primary clarifiers commonly perform this
function before biological treatment.
,3. Which treatment process is primarily responsible for converting ammonia to
nitrate under aerobic conditions?
A. Denitrification
B. Nitrification
C. Chlorination
D. Coagulation
Correct Answer: B. Nitrification
Nitrification is an aerobic biological process in which microorganisms oxidize
ammonia first to nitrite and then to nitrate. Denitrification, in contrast, converts
nitrate to nitrogen gas under anoxic conditions.
4. Which air pollutant is most directly associated with the formation of ground-
level ozone through photochemical reactions?
A. Carbon monoxide alone
B. Nitrogen oxides and volatile organic compounds
C. Sulfur dioxide and particulate matter
D. Lead and mercury
Correct Answer: B. Nitrogen oxides and volatile organic compounds
Ground-level ozone is a secondary pollutant formed when nitrogen oxides and
volatile organic compounds react in the presence of sunlight. It is therefore not
normally emitted directly from a single source.
5. What is the principal function of a baghouse in an air-pollution-control
system?
A. Remove particulate matter from an exhaust stream
B. Convert sulfur dioxide to sulfuric acid
C. Destroy volatile organic compounds thermally
D. Increase stack temperature
Correct Answer: A. Remove particulate matter from an exhaust stream
A baghouse uses fabric filter bags to capture particulate matter from a gas
stream. The collected particles accumulate on the filter surface and are
periodically removed through cleaning mechanisms.
,6. Which mechanism is primarily responsible for removing dissolved
contaminants from water by activated carbon?
A. Sedimentation
B. Adsorption
C. Nitrification
D. Screening
Correct Answer: B. Adsorption
Activated carbon has a highly porous structure and large surface area that allows
many dissolved organic compounds and other contaminants to attach to its
surface through adsorption.
7. In groundwater remediation, what is the primary purpose of a monitoring
well?
A. Increase groundwater velocity
B. Measure and sample groundwater conditions
C. Prevent all groundwater movement
D. Replace a drinking-water well
Correct Answer: B. Measure and sample groundwater conditions
Monitoring wells provide controlled access to groundwater for measuring water
levels and collecting samples. They are important for determining contaminant
concentrations and evaluating remediation progress.
8. A soil sample contains a high concentration of petroleum hydrocarbons.
Which remediation approach is specifically designed to promote microbial
degradation of biodegradable contaminants?
A. Bioremediation
B. Incineration
C. Sedimentation
D. Membrane filtration
Correct Answer: A. Bioremediation
, Bioremediation uses microorganisms and appropriate environmental conditions to
break down contaminants. Nutrient availability, oxygen conditions, moisture, and
contaminant characteristics can affect its effectiveness.
9. What is the primary environmental concern associated with excessive
nutrient discharge into surface waters?
A. Increased corrosion of steel
B. Eutrophication
C. Increased soil compaction
D. Reduced atmospheric pressure
Correct Answer: B. Eutrophication
Excess nitrogen and phosphorus can stimulate excessive algae and aquatic plant
growth. When this biomass decomposes, oxygen can be depleted, potentially
creating harmful conditions for aquatic organisms.
10. Which measurement is most directly used to determine the acidity or
alkalinity of an aqueous solution?
A. Turbidity
B. Conductivity
C. pH
D. Dissolved oxygen
Correct Answer: C. pH
pH expresses the hydrogen-ion activity of a solution on a logarithmic scale. It is
commonly used to characterize whether water is acidic, neutral, or alkaline.
11. What is the primary purpose of coagulation during drinking-water
treatment?
A. Convert nitrate to nitrogen gas
B. Destabilize suspended and colloidal particles
C. Increase water temperature
D. Remove dissolved oxygen
Correct Answer: B. Destabilize suspended and colloidal particles
6056 Practice Test Questions and
Correct Answers (Verified Answers) Plus
Rationales 2025|2026 Q&A | Instant
download Pdf
1. Which parameter is most directly used to indicate the amount of oxygen
required to biologically degrade biodegradable organic matter in wastewater?
A. Total dissolved solids
B. Chemical oxygen demand
C. Biochemical oxygen demand
D. Alkalinity
Correct Answer: C. Biochemical oxygen demand
Biochemical oxygen demand (BOD) measures the amount of dissolved oxygen
microorganisms require to biologically decompose biodegradable organic material
in water. It is a fundamental parameter for evaluating wastewater strength and
treatment performance.
2. What is the primary purpose of a sedimentation basin in conventional
wastewater treatment?
A. Remove settleable suspended solids
B. Increase dissolved oxygen
C. Destroy dissolved pathogens through ultraviolet radiation
D. Convert ammonia directly to nitrogen gas
Correct Answer: A. Remove settleable suspended solids
Sedimentation allows suspended particles that are denser than water to settle
under relatively quiescent conditions. Primary clarifiers commonly perform this
function before biological treatment.
,3. Which treatment process is primarily responsible for converting ammonia to
nitrate under aerobic conditions?
A. Denitrification
B. Nitrification
C. Chlorination
D. Coagulation
Correct Answer: B. Nitrification
Nitrification is an aerobic biological process in which microorganisms oxidize
ammonia first to nitrite and then to nitrate. Denitrification, in contrast, converts
nitrate to nitrogen gas under anoxic conditions.
4. Which air pollutant is most directly associated with the formation of ground-
level ozone through photochemical reactions?
A. Carbon monoxide alone
B. Nitrogen oxides and volatile organic compounds
C. Sulfur dioxide and particulate matter
D. Lead and mercury
Correct Answer: B. Nitrogen oxides and volatile organic compounds
Ground-level ozone is a secondary pollutant formed when nitrogen oxides and
volatile organic compounds react in the presence of sunlight. It is therefore not
normally emitted directly from a single source.
5. What is the principal function of a baghouse in an air-pollution-control
system?
A. Remove particulate matter from an exhaust stream
B. Convert sulfur dioxide to sulfuric acid
C. Destroy volatile organic compounds thermally
D. Increase stack temperature
Correct Answer: A. Remove particulate matter from an exhaust stream
A baghouse uses fabric filter bags to capture particulate matter from a gas
stream. The collected particles accumulate on the filter surface and are
periodically removed through cleaning mechanisms.
,6. Which mechanism is primarily responsible for removing dissolved
contaminants from water by activated carbon?
A. Sedimentation
B. Adsorption
C. Nitrification
D. Screening
Correct Answer: B. Adsorption
Activated carbon has a highly porous structure and large surface area that allows
many dissolved organic compounds and other contaminants to attach to its
surface through adsorption.
7. In groundwater remediation, what is the primary purpose of a monitoring
well?
A. Increase groundwater velocity
B. Measure and sample groundwater conditions
C. Prevent all groundwater movement
D. Replace a drinking-water well
Correct Answer: B. Measure and sample groundwater conditions
Monitoring wells provide controlled access to groundwater for measuring water
levels and collecting samples. They are important for determining contaminant
concentrations and evaluating remediation progress.
8. A soil sample contains a high concentration of petroleum hydrocarbons.
Which remediation approach is specifically designed to promote microbial
degradation of biodegradable contaminants?
A. Bioremediation
B. Incineration
C. Sedimentation
D. Membrane filtration
Correct Answer: A. Bioremediation
, Bioremediation uses microorganisms and appropriate environmental conditions to
break down contaminants. Nutrient availability, oxygen conditions, moisture, and
contaminant characteristics can affect its effectiveness.
9. What is the primary environmental concern associated with excessive
nutrient discharge into surface waters?
A. Increased corrosion of steel
B. Eutrophication
C. Increased soil compaction
D. Reduced atmospheric pressure
Correct Answer: B. Eutrophication
Excess nitrogen and phosphorus can stimulate excessive algae and aquatic plant
growth. When this biomass decomposes, oxygen can be depleted, potentially
creating harmful conditions for aquatic organisms.
10. Which measurement is most directly used to determine the acidity or
alkalinity of an aqueous solution?
A. Turbidity
B. Conductivity
C. pH
D. Dissolved oxygen
Correct Answer: C. pH
pH expresses the hydrogen-ion activity of a solution on a logarithmic scale. It is
commonly used to characterize whether water is acidic, neutral, or alkaline.
11. What is the primary purpose of coagulation during drinking-water
treatment?
A. Convert nitrate to nitrogen gas
B. Destabilize suspended and colloidal particles
C. Increase water temperature
D. Remove dissolved oxygen
Correct Answer: B. Destabilize suspended and colloidal particles
