Environmental Engineering PE Exam Flashcards
6 cards from real NCEES practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Environmental Engineering PE Exam flashcards as text
On the NCEES PE Environmental exam, what is the 'solids retention time (SRT)' or sludge age in an activated sludge system?
Answer: The average time microorganisms remain in the system before being wasted, controlling biological process performance
SRT (= total mass of VSS in system / daily VSS wasted) controls the microbial community — longer SRT enables nitrification, while shorter SRT may wash out slow-growing organisms.
In the NCEES PE Environmental exam, which soil characteristic is most important for evaluating the suitability of a site for a septic drain field?
Answer: Hydraulic conductivity and percolation rate
Hydraulic conductivity (percolation rate) determines whether the soil can accept and treat septic effluent; soils must be permeable enough to accept effluent but fine enough to provide treatment.
For the NCEES PE Environmental exam, what is 'air stripping' used to treat in water and wastewater?
Answer: Volatile organic compounds (VOCs) by transferring them from water to air
Air stripping passes contaminated water through a packed tower countercurrent to air, transferring volatile contaminants (TCE, benzene, radon) from the aqueous phase to the gas phase.
On the NCEES PE Environmental exam, what does 'hazard quotient (HQ)' represent in human health risk assessment?
Answer: The ratio of estimated exposure to a non-carcinogen to its reference dose, indicating whether adverse effects are likely
Hazard quotient = exposure/reference dose (RfD); an HQ > 1 suggests the exposure exceeds the threshold below which adverse health effects are unlikely for non-carcinogenic chemicals.
In the NCEES PE Environmental exam, which primary air quality standard under the CAA is set to protect human health?
Answer: Primary National Ambient Air Quality Standards (NAAQS)
Primary NAAQS are set by EPA under the Clean Air Act to protect public health with an adequate margin of safety for criteria pollutants including ozone, PM2.5, CO, NOx, SO2, and lead.
For the NCEES PE Environmental exam, what is the purpose of 'secondary treatment' in a municipal wastewater treatment plant?
Answer: Biological oxidation of dissolved and colloidal organic matter to meet effluent BOD/TSS standards
Secondary treatment uses biological processes (activated sludge, trickling filter, etc.) to remove dissolved BOD and suspended solids that primary clarification cannot remove.
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