Physical removal of particles from the sewage takes place in which of the following treatments?
Physical removal of particles from the sewage takes place in which of the following treatments?
The correct option is A Primary treatment
Sewage refers to the waste water that is generated every day in the cities and towns. It contains organic wastes and microbes (most of which are pathogenic in nature). The organic part of sewage is mainly composed of faecal matter.
Dumping sewage directly into water bodies like lakes, rivers, etc results in water pollution. Thus, sewage is properly treated in sewage treatment plants, for the removal of wastes, before being released into the water bodies.
Sewage treatment starts with the primary treatment which involves physical removal of small and large particles. Initially the floating particles are removed via filtration through filters that trap the floating debris and allow the rest of the fluid to pass through.
Filtration is followed by the removal of heavier particles like grit (soil and small pebbles) by sedimentation. Sedimentation involves pouring of the sewage into large settling tanks and keeping it undisturbed. It results in settling of the heavier insoluble particles due to gravity. All solids that settle form the primary sludge and the liquid above it is known as the primary effluent.
The primary effluent is further subjected to secondary treatment which involves digestion of the organic matter by the action of heterotrophic microbes. These organisms digest the organic matter and reduce the level of organic pollutants in the water. The effluent is then transferred to a final settling tank, where microbes are allowed to settle down. This sediment is called activated sludge. The effluent or supernatant is discharged into rivers or streams.
The major part of the activated sludge is fed into anaerobic sludge digesters where anaerobic microbes digest the organisms present in it. The rest of the activated sludge is used as an inoculum to initiate the growth of heterotrophic microbes in the further operation of secondary treatment of sewage.
Hence, physical removal of particles from the sewage takes place in the primary treatment of sewage.
Sewage refers to the waste water that is generated every day in the cities and towns. It contains organic wastes and microbes (most of which are pathogenic in nature). The organic part of sewage is mainly composed of faecal matter.
Dumping sewage directly into water bodies like lakes, rivers, etc results in water pollution. Thus, sewage is properly treated in sewage treatment plants, for the removal of wastes, before being released into the water bodies.
Sewage treatment starts with the primary treatment which involves physical removal of small and large particles. Initially the floating particles are removed via filtration through filters that trap the floating debris and allow the rest of the fluid to pass through.
Filtration is followed by the removal of heavier particles like grit (soil and small pebbles) by sedimentation. Sedimentation involves pouring of the sewage into large settling tanks and keeping it undisturbed. It results in settling of the heavier insoluble particles due to gravity. All solids that settle form the primary sludge and the liquid above it is known as the primary effluent.
The primary effluent is further subjected to secondary treatment which involves digestion of the organic matter by the action of heterotrophic microbes. These organisms digest the organic matter and reduce the level of organic pollutants in the water. The effluent is then transferred to a final settling tank, where microbes are allowed to settle down. This sediment is called activated sludge. The effluent or supernatant is discharged into rivers or streams.
The major part of the activated sludge is fed into anaerobic sludge digesters where anaerobic microbes digest the organisms present in it. The rest of the activated sludge is used as an inoculum to initiate the growth of heterotrophic microbes in the further operation of secondary treatment of sewage.
Hence, physical removal of particles from the sewage takes place in the primary treatment of sewage.
