CBSE 2025 · Region 6 · Set 1 · Q27 · 3 marks
(a)What do you mean by activated sludge in an STP ?(b)Explain the biological treatment of the major part of the sludge transferred from the large aeration tank into the anaerobic sludge digesters before its final release into the natural water bodies.
(a)
What do you mean by activated sludge in an STP ?
(b)
Explain the biological treatment of the major part of the sludge transferred from the large aeration tank into the anaerobic sludge digesters before its final release into the natural water bodies.
Marking-scheme solution
(a)
Sedimented bacterial flocs in settling tank is called activated sludge
(b)
In anaerobic sludge digester bacteria digest the bacteria and the fungi in the
sludge, during this digestion bacteria produce a mixture of gases (such as methane, hydrogen sulphide and carbon dioxide)
Microbes in Human WelfareMicrobes in Sewage TreatmentUnderstandshort_answermedium
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CBSE Class 12 Biology past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.