BCE Environmental Engineering 1 — Questions and Answers
Question 1: What does BOD stand for in water quality assessment?
- Biological Oxygen Demand
- Biochemical Oxygen Demand (Correct answer)
- Basic Organic Degradation
- Bacterial Oxidation Dynamics
Correct answer: Biochemical Oxygen Demand
BOD (Biochemical Oxygen Demand) measures the amount of dissolved oxygen consumed by biological organisms when decomposing organic matter in a given water sample over a set period.
Question 2: Which unit process in a conventional water treatment plant removes suspended solids by settling?
- Coagulation
- Sedimentation (Correct answer)
- Filtration
- Disinfection
Correct answer: Sedimentation
Sedimentation (clarification) allows suspended solids and floc formed during coagulation and flocculation to settle out of the water under gravity.
Question 3: The primary purpose of chlorination in drinking water treatment is:
- To remove hardness
- To disinfect and kill pathogens (Correct answer)
- To reduce turbidity
- To remove dissolved iron
Correct answer: To disinfect and kill pathogens
Chlorination is the primary disinfection method used to kill or inactivate pathogens (bacteria, viruses, protozoa) in drinking water to make it safe for human consumption.
Question 4: What is the main objective of primary wastewater treatment?
- Biological removal of dissolved nutrients
- Physical removal of settleable solids and floating material (Correct answer)
- Disinfection of effluent
- Chemical precipitation of heavy metals
Correct answer: Physical removal of settleable solids and floating material
Primary treatment uses physical processes (screening, sedimentation) to remove approximately 60% of suspended solids and 35% of BOD from raw wastewater.
Question 5: Which parameter measures the acid-neutralizing capacity of a water body?
- pH
- Hardness
- Alkalinity (Correct answer)
- Turbidity
Correct answer: Alkalinity
Alkalinity measures a water's capacity to neutralize acids, primarily due to bicarbonate, carbonate, and hydroxide ions, and is expressed in mg/L as CaCO₃.
Question 6: Eutrophication of water bodies is primarily caused by excess concentrations of which nutrients?
- Iron and manganese
- Nitrogen and phosphorus (Correct answer)
- Calcium and magnesium
- Chloride and sulfate
Correct answer: Nitrogen and phosphorus
Eutrophication is driven by excess nitrogen and phosphorus from agricultural runoff, sewage, and stormwater, stimulating excessive algal and aquatic plant growth.
BCE Environmental Engineering 1
What does BOD stand for in water quality assessment?