Biology Multiple Choice Questions on “Microbes in Sewage Treatment”.
1. What is the major component of waste-water?
a) Pure water
b) Human excreta
c) Sand
d) Clay
Answer: b
Clarification: A major component of this waste-water is human excreta. This municipal waste-water is also called as sewage. It contains a large amount of organic matter and microbes. Many of which are pathogenic.
2. What is the full form of STPs?
a) Sexually transmitted problems
b) Sewage treatment plants
c) Serum tissue plasminogen
d) Sebaceous tissue plasminogen
Answer: b
Clarification: STP stands for sewage treatment plants. Before the disposal of waste-water into the natural water bodies, sewage is treated in STPs to make it less polluting.
3. In how many stages the treatment of waste-water in STPs is carried out?
a) One
b) Two
c) Three
d) Four
Answer: b
Clarification: The treatment of waste-water in STPs is carried out in two stages namely primary treatment and secondary treatment. Treatment of waste-water is done by the heterotrophic microbes naturally present in the sewage.
4. Primary treatment involves filtration and distillation.
a) False
b) True
Answer: a
Clarification: Primary treatment involves the basic removal of particles- large and small-from the sewage through filtration and sedimentation. These particles are removed further in various stages.
5. Which of the following is not correct regarding the primary treatment of waste-water?
a) Initially floating debris is removed by distillation
b) Grit and pebbles are removed by sedimentation
c) Solids that settle form the primary sludge
d) Supernatant forms the effluent
Answer: a
Clarification: In primary treatment, initially floating debris is removed by sequential filtration. Then grit and small pebbles are removed by sedimentation. All solids that settle form the primary sludge while the supernatant forms the effluent.
6. The effluent from the primary settling tank is taken for secondary treatment.
a) True
b) False
Answer: a
Clarification: The effluent from the primary settling tank is taken for secondary treatment. The primary effluent is then passed into large aeration tanks where it is constantly agitated mechanically and the air is pumped into it.
7. What are flocs?
a) Masses of fungi
b) Masses of algae
c) Masses of animals
d) Masses of bacteria
Answer: d
Clarification: The constant agitation of primary effluent allows vigorous growth of useful aerobic microbes into flocs which are the masses of bacteria associated with fungal filaments to form mesh-like structures.
8. What is the full form of BOD?
a) Biochemical oxygen demand
b) Bionatal oxygen demand
c) Biological disease
d) Biological oxygen deficiency
Answer: a
Clarification: BOD refers to the Biochemical oxygen demand. It is the amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria.
9. Which of the following statements is not true regarding BOD?
a) Sewage water is treated until the BOD is reduced.
b) BOD is a measure of organic matter present in the water
c) Greater the BOD, lesser is the polluting potential of water
d) BOD measures the rate of uptake of oxygen