118
Question
In the primary treatment of sewage, all solids that settle after sedimentation form the___(i)_____and the supernatant forms the___(ii)____.
In the primary treatment of sewage, all solids that settle after sedimentation form the___(i)_____and the supernatant forms the___(ii)____.
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Solution
The correct option is B (i) - primary sludge, (ii) - effluent
Sewage, also called municipal wastewater, contains human excreta, organic wastes and various pathogens (disease causing microorganisms). Releasing it directly into the water bodies poses a high threat to aquatic life and causes water pollution. Hence, the sewage is treated in the sewage treatment plants (STPs) before it is released into the water bodies.
Primary treatment of sewage includes removal of particles from the sewage by sequential filtration (to remove the floating debris) and sedimentation (to remove the soil and small pebbles).
The solids that settle form the primary sludge. It usually consists of soil and small pebbles which are called grit.
After sedimentation, the fluid that remains above the sediment is called as effluent and it is subjected to secondary treatment.
Secondary treatment involves oxidation of the organic matter present in the sewage by the enzymatic actions of aerobic microbes, in the presence of oxygen.
Activated sludge is formed during the secondary treatment of sewage.
Sewage, also called municipal wastewater, contains human excreta, organic wastes and various pathogens (disease causing microorganisms). Releasing it directly into the water bodies poses a high threat to aquatic life and causes water pollution. Hence, the sewage is treated in the sewage treatment plants (STPs) before it is released into the water bodies.
Primary treatment of sewage includes removal of particles from the sewage by sequential filtration (to remove the floating debris) and sedimentation (to remove the soil and small pebbles).
The solids that settle form the primary sludge. It usually consists of soil and small pebbles which are called grit.
After sedimentation, the fluid that remains above the sediment is called as effluent and it is subjected to secondary treatment.
Secondary treatment involves oxidation of the organic matter present in the sewage by the enzymatic actions of aerobic microbes, in the presence of oxygen.
Activated sludge is formed during the secondary treatment of sewage.
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