UPSC Prelims 2015 Q93: Science & Technology – Biotechnology & Genetics
With reference to bio - toilets used by the Indian Railways, consider the following statements:
1. The decomposition of human waste in the bio - toilets is initiated by a fungal inoculum.
2. Ammonia and water vapour are the only end products in this decomposition which are
released into the atmosphere.
Which of the statements given above is/are correct?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer: (d) Neither 1 nor 2
Explanation
Bio-toilets of the Indian Railways
The bio-toilets were developed by the Railways with DRDO.
Human waste is collected in a tank under the coach and broken down by bacteria.
| Statement | Verdict | Fact |
|---|---|---|
| 1. The decomposition of human waste in the bio-toilets is initiated by a fungal inoculum | Incorrect | It uses a bacterial inoculum of anaerobic bacteria |
| 2. Ammonia and water vapour are the only end products released into the atmosphere | Incorrect | The end products are mainly methane, carbon dioxide and water |
How a bio-toilet works:
| Step | Detail |
|---|---|
| Inoculum | Anaerobic bacteria, first isolated by DRDO from cold regions |
| Process | Anaerobic digestion in a sealed tank |
| Output | Gases escape; treated water is disinfected and let out |
| Benefit | No raw waste on the tracks; less corrosion of rails |
Answer: (d) Neither 1 nor 2.
Why each option is right or wrong
- (a) Incorrect. The inoculum is bacterial, not fungal.
- (b) Incorrect. Ammonia and water vapour are not the only end products.
- (c) Incorrect. Both statements are false.
- (d) CORRECT. Anaerobic bacteria do the work, giving methane, carbon dioxide and water.
Key point
Railway bio-toilets (DRDO): anaerobic bacterial digestion of waste into methane, carbon dioxide and water; keeps tracks clean.
Remember
Bio-toilet = anaerobic bacteria, methane + CO2 + water.
Common mistakes
- Accepting fungal for bacterial.
- Accepting 'only' in statement 2.
- Thinking the process needs oxygen; it is anaerobic.
Exam tip
Bio-digester = bacteria without oxygen = methane.
Sources
- Ministry of Railways — Bio-toilets in Indian Railways coaches
- Defence Research and Development Organisation — Biodigester technology