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Question
Assertion: A major part of the activated sludge is pumped into large tanks called anaerobic sludge digesters.
Reason: During anaerobic digestion, the anaerobic bacteria digest the organisms present in the primary sludge.
Assertion: A major part of the activated sludge is pumped into large tanks called anaerobic sludge digesters.
Reason: During anaerobic digestion, the anaerobic bacteria digest the organisms present in the primary sludge.
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Solution
The correct option is C Assertion is true and the reason is false
The large quantities of waste water that is generated every day in cities and towns is known as sewage. It contains human excreta, large amounts of organic matter (food waste) and pathogenic microbes. It is treated in sewage treatment plants (STPs) before it is discharged into natural water bodies.
The first stage of treatment is called primary treatment. It involves the physical removal of particles from the sewage through filtration and sedimentation. The heavier particles such as soil and small pebbles (grit) settle down under the effect of gravity and form the sediment which is referred to as primary sludge. The supernatant formed is called the primary effluent.
The primary effluent thus obtained undergoes secondary/biological treatment during which digestion of the organic matter by heterotrophic microorganisms that are naturally present in sewage takes place. Masses of bacteria become associated with fungal filaments to form mesh-like structures known as flocs. As the microbes grow and increase in number, they consume a major part of the organic matter in the effluent which significantly reduces its polluting potential. After there is considerable decrease in the organic matter, the effluent is passed into a settling tank where the bacterial ‘flocs’ are allowed to sediment. This sediment is called activated sludge.
A major part of the activated sludge is pumped into large tanks called anaerobic sludge digesters. Here, anaerobic bacteria digest the aerobic bacteria and the fungi in the sludge. During this digestion, the anaerobic bacteria produce a mixture of gases which include methane, hydrogen sulphide and carbon dioxide. These gases form biogas and may be used as a source of energy as it is inflammable.
Hence, the assertion is true but the reason is false.
The large quantities of waste water that is generated every day in cities and towns is known as sewage. It contains human excreta, large amounts of organic matter (food waste) and pathogenic microbes. It is treated in sewage treatment plants (STPs) before it is discharged into natural water bodies.
The first stage of treatment is called primary treatment. It involves the physical removal of particles from the sewage through filtration and sedimentation. The heavier particles such as soil and small pebbles (grit) settle down under the effect of gravity and form the sediment which is referred to as primary sludge. The supernatant formed is called the primary effluent.
The primary effluent thus obtained undergoes secondary/biological treatment during which digestion of the organic matter by heterotrophic microorganisms that are naturally present in sewage takes place. Masses of bacteria become associated with fungal filaments to form mesh-like structures known as flocs. As the microbes grow and increase in number, they consume a major part of the organic matter in the effluent which significantly reduces its polluting potential. After there is considerable decrease in the organic matter, the effluent is passed into a settling tank where the bacterial ‘flocs’ are allowed to sediment. This sediment is called activated sludge.
A major part of the activated sludge is pumped into large tanks called anaerobic sludge digesters. Here, anaerobic bacteria digest the aerobic bacteria and the fungi in the sludge. During this digestion, the anaerobic bacteria produce a mixture of gases which include methane, hydrogen sulphide and carbon dioxide. These gases form biogas and may be used as a source of energy as it is inflammable.
Hence, the assertion is true but the reason is false.
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