NCEES Environmental Engineering — Questions and Answers
Question 1: On the NCEES PE Environmental exam, the biochemical oxygen demand (BOD) test measures:
- The chemical oxygen demand of industrial effluents at high temperature
- The amount of dissolved oxygen consumed by microorganisms in degrading organic matter (Correct answer)
- The total dissolved solids in a water sample
- The oxygen saturation of surface water streams
Correct answer: The amount of dissolved oxygen consumed by microorganisms in degrading organic matter
BOD measures the dissolved oxygen consumed by aerobic biological organisms decomposing organic material in water at 20°C over 5 days.
Question 2: In NCEES PE Environmental engineering, the primary treatment of wastewater involves:
- Biological nutrient removal
- Physical removal of settleable solids and floating materials (Correct answer)
- Chemical precipitation of heavy metals
- UV disinfection of pathogens
Correct answer: Physical removal of settleable solids and floating materials
Primary treatment uses physical processes (screening, sedimentation) to remove settleable solids and floating materials from wastewater.
Question 3: According to NCEES PE Environmental standards, the maximum contaminant level (MCL) for nitrate in drinking water is:
- 1 mg/L as N
- 10 mg/L as N (Correct answer)
- 50 mg/L as N
- 100 mg/L as N
Correct answer: 10 mg/L as N
The US EPA MCL for nitrate in drinking water is 10 mg/L as nitrogen to prevent methemoglobinemia (blue baby syndrome).
Question 4: In NCEES PE Environmental practice, the Streeter-Phelps model describes:
- Groundwater flow in confined aquifers
- Dissolved oxygen sag in streams downstream of an organic waste discharge (Correct answer)
- Atmospheric dispersion of air pollutants from a point source
- Leachate migration through landfill liners
Correct answer: Dissolved oxygen sag in streams downstream of an organic waste discharge
The Streeter-Phelps equation models the dissolved oxygen deficit in streams as BOD exerts oxygen demand while reaeration occurs.
Question 5: On the NCEES PE Environmental exam, which unit process is used to remove hardness (Ca²⁺ and Mg²⁺) from drinking water?
- Chlorination
- Coagulation-flocculation
- Lime-soda softening (Correct answer)
- Activated carbon adsorption
Correct answer: Lime-soda softening
Lime-soda softening precipitates calcium as CaCO₃ and magnesium as Mg(OH)₂ to reduce water hardness.
Question 6: In NCEES PE Environmental engineering, the Darcy-Weisbach equation is used to calculate:
- Groundwater seepage velocity
- Head loss due to friction in pipes (Correct answer)
- Evapotranspiration rates in watersheds
- Settling velocity of particles
Correct answer: Head loss due to friction in pipes
The Darcy-Weisbach equation hf = f(L/D)(V²/2g) calculates friction head loss in pipes using the friction factor f.
NCEES Environmental Engineering
On the NCEES PE Environmental exam, the biochemical oxygen demand (BOD) test measures: