NCEES Environmental Engineering

Question 1

On the NCEES PE Environmental exam, the biochemical oxygen demand (BOD) test measures:

Accepted Answer

The amount of dissolved oxygen consumed by microorganisms in degrading organic matter

Answer

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:

Accepted Answer

Physical removal of settleable solids and floating materials

Answer

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:

Accepted Answer

10 mg/L as N

Answer

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:

Accepted Answer

Dissolved oxygen sag in streams downstream of an organic waste discharge

Answer

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?

Accepted Answer

Lime-soda softening

Answer

Lime-soda softening precipitates calcium as CaCO₃ and magnesium as Mg(OH)₂ to reduce water hardness.

NCEES Practice Test