Primary Sewage Treatment Steps — NEET Biology
✅ Asked in NEET 2017Which of the following in sewage treatment removes suspended solids? (NEET 2017)
Which of the following in sewage treatment removes suspended solids? (NEET 2017)
Answer & NCERT explanation
Correct answer: B — Primary treatment
Primary treatment in sewage removes suspended solids through physical processes like screening, grit removal, and sedimentation. Secondary treatment uses biological processes, tertiary treatment provides advanced purification, and sludge treatment processes the settled solids.
Read more NCERT concept on the PYQ
Primary treatment: These treatment steps basically involve physical removal of particles – large and small – from the sewage through filtration and sedimentation. These are removed in stages; initially, floating debris is removed by sequential filtration. Then the grit (soil and small pebbles) are removed by sedimentation. All solids that settle form the primary sludge, and the supernatant forms the effluent. The effluent from the primary settling tank is taken for secondary treatment.
Primary treatment removes large and small particles from sewage through physical processes like filtration and sedimentation, not biological or chemical methods. Students often confuse primary treatment with secondary treatment, thinking microorganisms are involved from the start—they're not. Primary treatment only physically separates solids (forming primary sludge) from liquid effluent. Remember: primary = physical removal only, secondary = biological treatment with microorganisms. NTA tests this distinction because understanding treatment stages is crucial for topics on water pollution, sewage management, and microbial roles in human welfare.
What does NCERT say about Primary treatment These treatment?
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