GATE 2023 CE (CE2) – Question 49
Which of the following statements is/are TRUE for the aerobic composting of sewage sludge?
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Correct answer: (B) Leachate can be generated during composting; (C) Actinomycetes are involved in the process
Explanation
Check each statement about aerobic composting of sewage sludge.
- **A. A bulking agent is added to reduce porosity.** False. Bulking agents (wood chips, straw) are added to **increase** porosity and air space so that oxygen can reach the microbes.
- **B. Leachate can be generated.** True. Moisture squeezed out of the pile, and rain on open piles, produces leachate. ✓
- **C. Actinomycetes are involved.** True. They are active in the later (curing) stages and break down resistant organic matter. ✓
- **D. In-vessel systems cannot operate in plug-flow mode.** False. Many in-vessel systems (tunnels, channels) work as plug-flow reactors, with material moving through from the feed end to the discharge end.
Correct: **B and C**.