BCE Environmental Engineering 2 — Questions and Answers
Question 1: Which type of lagoon uses only natural processes (wind, sunlight, algae) for wastewater treatment?
- Activated sludge lagoon
- Stabilization pond (Correct answer)
- Sequencing batch reactor
- Trickling filter
Correct answer: Stabilization pond
Stabilization ponds (waste stabilization ponds) rely on natural sunlight, wind, and algal-bacterial symbiosis for wastewater treatment without mechanical aeration.
Question 2: What is the purpose of the activated sludge process in secondary wastewater treatment?
- To remove grit and large solids
- To biologically degrade dissolved organic matter using microorganisms (Correct answer)
- To chemically precipitate phosphorus
- To disinfect the effluent with UV light
Correct answer: To biologically degrade dissolved organic matter using microorganisms
The activated sludge process uses a biologically active suspension of microorganisms in an aeration tank to metabolize dissolved and colloidal organic matter from wastewater.
Question 3: Solid waste disposed in a sanitary landfill must be compacted and covered daily primarily to:
- Increase the landfill's capacity
- Control odors, vectors, and fire hazards (Correct answer)
- Accelerate leachate generation
- Reduce gas production
Correct answer: Control odors, vectors, and fire hazards
Daily cover of compacted solid waste controls odors, prevents vector attraction (rodents, flies), reduces fire risk, and controls litter blowing off the site.
Question 4: Which air pollutant is primarily responsible for acid rain?
- Carbon dioxide (CO₂) and methane (CH₄)
- Sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) (Correct answer)
- Particulate matter (PM2.5)
- Ground-level ozone (O₃)
Correct answer: Sulfur dioxide (SO₂) and nitrogen oxides (NOₓ)
Acid rain results from SO₂ and NOₓ emissions (primarily from fossil fuel combustion) that react with water vapor in the atmosphere to form sulfuric and nitric acids.
Question 5: What is the environmental significance of the dissolved oxygen (DO) level in a stream?
- It indicates the concentration of heavy metals
- It reflects the ability of the stream to support aquatic life and indicates organic pollution levels (Correct answer)
- It measures the rate of sedimentation
- It determines the hardness of the water
Correct answer: It reflects the ability of the stream to support aquatic life and indicates organic pollution levels
DO levels indicate both the health of the aquatic ecosystem and the degree of organic pollution; low DO caused by BOD exertion stresses or kills fish and other organisms.
Question 6: The USEPA's National Ambient Air Quality Standards (NAAQS) regulate which group of pollutants called 'criteria pollutants'?
- SO₂, NO₂, CO, O₃, PM₂.₅/PM₁₀, Pb (Correct answer)
- CO₂, CH₄, N₂O, HFCs, PFCs, SF₆
- PCBs, dioxins, furans, mercury, arsenic
- VOCs, HAPs, POPs, PFAS, BPA
Correct answer: SO₂, NO₂, CO, O₃, PM₂.₅/PM₁₀, Pb
NAAQS criteria pollutants are SO₂, NO₂, CO, O₃, particulate matter (PM₂.₅ and PM₁₀), and lead—six pollutants regulated based on health-based standards.
BCE Environmental Engineering 2
Which type of lagoon uses only natural processes (wind, sunlight, algae) for wastewater treatment?