Page 1 of 107
NCEES PE ENVIRONMENTAL ACTUAL EXAM WITH 200 QUESTIONS-
CORRECT VERIFIED AND DETAILED ANSWERS |ALREADY GRADED A+
|| LATEST UPDATE -JUST RELEASED
Environmental Engineering / Professional Engineering Licensure
Document description: -
Prepare for the NCEES Principles and Practice of Engineering (PE)
Environmental exam with computer‑based practice questions covering
all six topic areas: Water, Solid & Hazardous Waste, Sustainability, Air,
Site Assessment & Remediation, and Environmental & Occupational
Health. This test bank reflects the NCEES PE Environmental CBT Exam
Specifications effective April 2026 and includes both SI and USCS units.
Designed to reinforce applied engineering knowledge, regulatory
compliance, and sustainable design practices in a closed‑book format
using the NCEES electronic reference handbook. Suitable for engineers
with four or more years of experience seeking professional licensure in
environmental engineering.
Section 1: Water Engineering (Questions 1–50)
Question 1
A water sample has a pH of 6. What is the hydrogen ion concentration in
moles per liter?
A) 1 × 10⁻³ M
B) 1 × 10⁻⁴ M
C) 1 × 10⁻⁶ M
D) 1 × 10⁻⁸ M
Correct Answer: C
, Page 2 of 107
Rationale: By definition, pH = −log[H⁺]. Therefore, [H⁺] = 10⁻⁶ M.
Question 2
The primary purpose of coagulation in water treatment is to:
A) Kill pathogens
B) Remove dissolved salts
C) Destabilize colloidal particles
D) Remove taste and odor
Correct Answer: C
Rationale: Coagulation neutralizes the surface charges of colloidal
particles, allowing them to aggregate during flocculation so they can be
removed by sedimentation and filtration.
Question 3
The detention time in a sedimentation basin is calculated as:
A) Volume / Surface area
B) Flow rate / Volume
C) Volume / Flow rate
D) Surface area / Flow rate
Correct Answer: C
, Page 3 of 107
Rationale: Detention time equals basin volume divided by the influent
flow rate. This represents the average time water spends in the basin.
Question 4
Biochemical Oxygen Demand (BOD₅) measures:
A) Total oxygen in water
B) Chemical oxidizable matter
C) Oxygen used by microorganisms in 5 days
D) Nitrogen concentration
Correct Answer: C
Rationale: BOD₅ quantifies the amount of biodegradable organic matter
in water by measuring the oxygen consumed by microorganisms over a
5‑day incubation period.
Question 5
A groundwater sample impacted by agricultural activities is most likely to
have elevated concentrations of which contaminant?
A) Lead
B) Nitrates
C) Mercury
D) PCBs
Correct Answer: B
, Page 4 of 107
Rationale: Nitrates from fertilizer application commonly leach into
groundwater, leading to contamination. Elevated nitrates can cause
methemoglobinemia (“blue baby syndrome”) in infants.
Question 6
A wastewater treatment plant uses a free chlorine residual of 1.0 mg/L.
After 30 minutes contact time at pH 7, what is the primary factor that
determines whether the required CT value for Giardia inactivation has
been achieved?
A) The type of chlorine compound used
B) The water temperature
C) The alkalinity of the water
D) The total dissolved solids concentration
Correct Answer: B
Rationale: The CT value required for inactivation of Giardia depends on
temperature and pH. Colder water requires a higher CT (concentration ×
time) because inactivation rates slow at lower temperatures.
Question 7
In wastewater treatment, nitrification is carried out primarily by which
type of microorganisms?
A) Facultative anaerobes
B) Methanogenic archaea
C) Obligate aerobic nitrifiers
D) Sulfate‑reducing bacteria
NCEES PE ENVIRONMENTAL ACTUAL EXAM WITH 200 QUESTIONS-
CORRECT VERIFIED AND DETAILED ANSWERS |ALREADY GRADED A+
|| LATEST UPDATE -JUST RELEASED
Environmental Engineering / Professional Engineering Licensure
Document description: -
Prepare for the NCEES Principles and Practice of Engineering (PE)
Environmental exam with computer‑based practice questions covering
all six topic areas: Water, Solid & Hazardous Waste, Sustainability, Air,
Site Assessment & Remediation, and Environmental & Occupational
Health. This test bank reflects the NCEES PE Environmental CBT Exam
Specifications effective April 2026 and includes both SI and USCS units.
Designed to reinforce applied engineering knowledge, regulatory
compliance, and sustainable design practices in a closed‑book format
using the NCEES electronic reference handbook. Suitable for engineers
with four or more years of experience seeking professional licensure in
environmental engineering.
Section 1: Water Engineering (Questions 1–50)
Question 1
A water sample has a pH of 6. What is the hydrogen ion concentration in
moles per liter?
A) 1 × 10⁻³ M
B) 1 × 10⁻⁴ M
C) 1 × 10⁻⁶ M
D) 1 × 10⁻⁸ M
Correct Answer: C
, Page 2 of 107
Rationale: By definition, pH = −log[H⁺]. Therefore, [H⁺] = 10⁻⁶ M.
Question 2
The primary purpose of coagulation in water treatment is to:
A) Kill pathogens
B) Remove dissolved salts
C) Destabilize colloidal particles
D) Remove taste and odor
Correct Answer: C
Rationale: Coagulation neutralizes the surface charges of colloidal
particles, allowing them to aggregate during flocculation so they can be
removed by sedimentation and filtration.
Question 3
The detention time in a sedimentation basin is calculated as:
A) Volume / Surface area
B) Flow rate / Volume
C) Volume / Flow rate
D) Surface area / Flow rate
Correct Answer: C
, Page 3 of 107
Rationale: Detention time equals basin volume divided by the influent
flow rate. This represents the average time water spends in the basin.
Question 4
Biochemical Oxygen Demand (BOD₅) measures:
A) Total oxygen in water
B) Chemical oxidizable matter
C) Oxygen used by microorganisms in 5 days
D) Nitrogen concentration
Correct Answer: C
Rationale: BOD₅ quantifies the amount of biodegradable organic matter
in water by measuring the oxygen consumed by microorganisms over a
5‑day incubation period.
Question 5
A groundwater sample impacted by agricultural activities is most likely to
have elevated concentrations of which contaminant?
A) Lead
B) Nitrates
C) Mercury
D) PCBs
Correct Answer: B
, Page 4 of 107
Rationale: Nitrates from fertilizer application commonly leach into
groundwater, leading to contamination. Elevated nitrates can cause
methemoglobinemia (“blue baby syndrome”) in infants.
Question 6
A wastewater treatment plant uses a free chlorine residual of 1.0 mg/L.
After 30 minutes contact time at pH 7, what is the primary factor that
determines whether the required CT value for Giardia inactivation has
been achieved?
A) The type of chlorine compound used
B) The water temperature
C) The alkalinity of the water
D) The total dissolved solids concentration
Correct Answer: B
Rationale: The CT value required for inactivation of Giardia depends on
temperature and pH. Colder water requires a higher CT (concentration ×
time) because inactivation rates slow at lower temperatures.
Question 7
In wastewater treatment, nitrification is carried out primarily by which
type of microorganisms?
A) Facultative anaerobes
B) Methanogenic archaea
C) Obligate aerobic nitrifiers
D) Sulfate‑reducing bacteria
