Environmental Engineering Flashcards

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

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.

In NCEES PE Environmental engineering, the primary treatment of wastewater involves:

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.

According to NCEES PE Environmental standards, the maximum contaminant level (MCL) for nitrate in drinking water is:

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).

In NCEES PE Environmental practice, the Streeter-Phelps model describes:

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.

On the NCEES PE Environmental exam, which unit process is used to remove hardness (Ca²⁺ and Mg²⁺) from drinking water?

Answer: Lime-soda softening

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

In NCEES PE Environmental engineering, the Darcy-Weisbach equation is used to calculate:

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.