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Question
The image given below represents a sewage treatment plant (STP). Identify A, B and C.
The image given below represents a sewage treatment plant (STP). Identify A, B and C.
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Solution
The correct option is A A- Filtration tank, B-Aeration tank, C- Anaerobic sludge digester tank
Sewage is the waste water that is generated in cities and towns. Due to the high concentration of wastes and microbial content in sewage, it has to be treated before being poured into water bodies. This will decrease the level of contaminants and thus minimize the water pollution.
The sewage is treated in the sewage treatment plant in two stages: primary treatment and secondary treatment.
Primary treatment: It is carried out by two processes, sequential filtration and sedimentation. The sewage is passed through the filtration tank initially. Filtration occurs as the waste water passes progressively via smaller pores. This filters out the floating debris. The filtrate obtained is passed into large sedimentation tanks, which allows the sedimentation of solids like grit (soil and small pebbles). The sediment collected here is called primary sludge, and the liquid collected above it is called effluent. The sedimentation tank is marked as A in the image.
Secondary treatment: The primary effluent is passed into the aeration tank. The effluent is mechanically agitated with continuous air supply. The aeration tank is marked as B in the image. A large number of aerobic microbes grow rapidly and form mesh-like structures called flocs. They digest the organic matter present in the effluent. After the complete digestion of organic matter, the effluent is passed into the final settling tank. Sedimentation of the flocs takes place in this tank. The sediment obtained is called activated sludge. The liquid collected above the sediment is released into the water bodies. A part of this activated sludge is added to the aeration tank as an inoculum for the growth of microbes during the secondary treatment. The remaining activated sludge is pumped into the large tanks called anaerobic sludge digesters which is marked as C in the image. In these tanks, anaerobic bacteria digest the flocs of the activated sludge and release gases like methane, hydrogen sulphide and carbon dioxide. These form the biogas which can be used for cooking or lightning purposes.
Hence, option a is correct.
A- Filtration tank, B-Aeration tank, C- Anaerobic sludge digester tank.
Sewage is the waste water that is generated in cities and towns. Due to the high concentration of wastes and microbial content in sewage, it has to be treated before being poured into water bodies. This will decrease the level of contaminants and thus minimize the water pollution.
The sewage is treated in the sewage treatment plant in two stages: primary treatment and secondary treatment.
Primary treatment: It is carried out by two processes, sequential filtration and sedimentation. The sewage is passed through the filtration tank initially. Filtration occurs as the waste water passes progressively via smaller pores. This filters out the floating debris. The filtrate obtained is passed into large sedimentation tanks, which allows the sedimentation of solids like grit (soil and small pebbles). The sediment collected here is called primary sludge, and the liquid collected above it is called effluent. The sedimentation tank is marked as A in the image.
Secondary treatment: The primary effluent is passed into the aeration tank. The effluent is mechanically agitated with continuous air supply. The aeration tank is marked as B in the image. A large number of aerobic microbes grow rapidly and form mesh-like structures called flocs. They digest the organic matter present in the effluent. After the complete digestion of organic matter, the effluent is passed into the final settling tank. Sedimentation of the flocs takes place in this tank. The sediment obtained is called activated sludge. The liquid collected above the sediment is released into the water bodies. A part of this activated sludge is added to the aeration tank as an inoculum for the growth of microbes during the secondary treatment. The remaining activated sludge is pumped into the large tanks called anaerobic sludge digesters which is marked as C in the image. In these tanks, anaerobic bacteria digest the flocs of the activated sludge and release gases like methane, hydrogen sulphide and carbon dioxide. These form the biogas which can be used for cooking or lightning purposes.
Hence, option a is correct.
A- Filtration tank, B-Aeration tank, C- Anaerobic sludge digester tank.
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