✓ Board-verified
Biology · 2025 · 3 marks
CBSE 2025 · Region 6 · Set 1 · Q27
(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…
(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)
All Microbes in Human Welfare questions2025 question paperNCERT solutions: Microbes in Human WelfarePractice Microbes in Human Welfare →
More from Microbes in Human Welfare
- A list of organisms is given in column 'R', whereas in column 'S' a list of products produced by them: Select the option where the organisms are…2024
- Assertion: Activated sludge contains large population of bacteria. Reason (R): These bacteria help in anaerobic digestion of human waste in biogas…2026
- Microbes commonly used in kitchen are2026
- Explain the role of the following during the sewage treatment: flocs anaerobic sludge digester2024
- Assertion: Besides curdling of milk, LAB also improves its nutritional quality by increasing Vitamin B12. Reason (R): LAB, when present in the…2026
- Many members of genus Glomus form a mycorrhizial association with plants. Elaborate how is this association beneficial to the plants.2022
- Explain the role of microorganisms in the following: Reducing the sugar content in grape juice Production of a fuel2023
- The process of mineralization by microorganisms help in the release of:2025
CBSE Class 12 Biology past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.