CBSE 2023 · Region 1 · Set 1 · Q26 · 3 marks
Treatment of wastewater is done in a sewage treatment plant to make it less polluting. Explain the following with reference to this treatment process :(a)Primary sludge(b)Activated sludge(c)Anaerobic sludge digesters
Treatment of wastewater is done in a sewage treatment plant to make it less polluting. Explain the following with reference to this treatment process :
(a)
Primary sludge
(b)
Activated sludge
(c)
Anaerobic sludge digesters
Marking-scheme solution
(a) Primary Sludge: All the solids that settle down, during the primary treatment of sewage water.
(b) Activated Sludge: Produced during the secondary treatment or biological treatment of sewage, primary effluent + aerobic microbes flocs (bacteria and fungus) - get converted to a sediment whose BOD has reduced significantly.
(c) Anaerobic sludge digesters: Large tanks where activated sludge is treated with anaerobic bacteria which digest the bacteria and fungi, and produce a mixture of \(\displaystyle \mathrm{CH}_{4}\), \(\displaystyle \mathrm{H}_{2} \mathrm{~S}\) and \(\displaystyle \mathrm{CO}_{2}\) / Biogas
Microbes in Human WelfareMicrobes in Sewage TreatmentUnderstandshort_answermedium
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CBSE Class 12 Biology past-paper question from the 2023board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.