This set of Environmental Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Oxygen Demand”.
1. _____ is the amount of oxygen required to oxidize only organic matter in sewage.
a) Turbidity
b) BOD
c) COD
d) DO
View Answer
Explanation: BOD is the amount of oxygen required to oxidize only organic matter in sewage. It is always less than COD as COD oxidizes both organic and inorganic matter.
2. The full form of BOD is __________
a) Biodegradable oxygen demand
b) Biological oxygen demand
c) Biochemical oxygen demand
d) Bandwidth on demand
View Answer
Explanation: The full form of BOD is biochemical oxygen demand. It is measured in ppm or mg/L.
3. The biochemical oxygen demand is computed by __________
a) Dissolved oxygen / Dilution factor
b) Dissolved oxygen + Dilution factor
c) Dissolved oxygen – Dilution factor
d) Dissolved oxygen * Dilution factor
View Answer
Explanation: BOD = Dissolved oxygen * Dilution factor.
Where Dilution factor = Volume of diluted sewage sample / Volume of undiluted sewage sample.
4. The value of deoxygenation constant is independent of the temperature.
a) True
b) False
View Answer
Explanation: The value of deoxygenation constant is directly proportional to the temperature. It increases with increase in temperature.
5. Which of the following represents the first stage BOD in the following figure?
Figure: BOD vs time curve
a) ZR
b) RL
c) ZL
d) EP
View Answer
Explanation: ZL represents the first stage BOD from the given figure. The first stage BOD is also called as the carbonaceous demand.
6. Which of the following represents the second stage BOD in the following figure?
Figure: BOD vs time curve
a) LP
b) RL
c) ZL
d) EP
View Answer
Explanation: LP represents the second stage BOD from the given figure. The second stage BOD is also called as the nitrogenous demand.
7. The carbonaceous demand occurs due to oxidation of ______________
Figure: BOD vs time curve
a) Ammonia
b) Sulfur
c) Organic matter
d) Nitrogen
View Answer
Explanation: The carbonaceous demand occurs due to oxidation of organic matter. The carbonaceous demand is also called as the initial demand.
8. The nitrogenous demand occurs due to oxidation of ______________
Figure: BOD vs time curve
a) Ammonia
b) Sulfur
c) Organic matter
d) Nitrogen
View Answer
Explanation: The carbonaceous demand occurs due to oxidation of ammonia. The nitrogenous demand is also called as the final demand.
9. Which of the following is correctly matched in the following figure?
Figure: BOD vs time curve
a) ZR – Carbonaceous demand
b) RE – Nitrogenous demand
c) EP – Final demand
d) ZP – Combined demand
View Answer
Explanation: ZP is correctly paired and it represents the combined demand, which includes both carbonaceous and nitrogenous demand.
10. The nitrogenous demand begins after how many days?
Figure: BOD vs time curve
a) 1
b) 2
c) 3
d) 5
View Answer
Explanation: As the growth rate of nitrifying bacteria is slow, the nitrogenous demand begins after 5 days.
Sanfoundry Global Education & Learning Series – Environmental Engineering.
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