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Activity 13.5: NCERT book Science Class 10
Ever wondered what happens to waste after it’s thrown away? Activity 13.5 in the Class 10 NCERT Science book explores how different waste materials decompose, teaching us about waste management and the roles of biological and physical processes.
Understanding Waste Decomposition: Activity 13.5 from Class 10 Science
Materials Needed
- Various household waste materials (e.g., kitchen waste like spoilt food, vegetable peels, used tea leaves, milk packets, empty cartons, waste paper, empty medicine bottles/strips/bubble packs, old clothes, and broken footwear)
- A pit in the school garden or an old bucket/flower pot
- Soil (to cover the waste)
- Water (to keep the materials moist)
Procedure
- Collection of Waste: Start by collecting a variety of waste materials from your homes. This should include both biodegradable and non-biodegradable items.
- Burying the Waste: If you have access to a school garden, dig a pit and bury the waste materials in it. If not, use an old bucket or flower pot. Cover the waste with at least 15 cm of soil.
- Maintenance: Keep the waste moist by watering it regularly.
- Observation: Observe the buried waste at 15-day intervals to note which materials remain unchanged and which ones decompose.
Observations
- Biodegradable Materials: Over time, materials such as vegetable peels, used tea leaves, and food scraps are likely to decompose and change their form and structure. These materials are broken down by bacteria and other saprophytes present in the soil.
- Non-Biodegradable Materials: Items like plastic bags, empty medicine bottles, strips, and certain synthetic fabrics will remain largely unchanged. These materials do not easily break down through biological processes and may persist in the environment for a long time.
| Material Type | Examples | Decomposability | Approximate Time Taken for Decomposition |
|---|---|---|---|
| Biodegradable | Vegetable peels, Food scraps, Used tea leaves | Decomposes easily | 1-2 months |
| Paper, Cardboard, Cotton clothes | Decomposes fairly easily | 2-5 months | |
| Natural fabrics (wool, silk) | Decomposes | 1-5 years | |
| Non-Biodegradable | Plastic bottles, Plastic bags | Does not decompose easily | 450 years |
| Glass bottles, Metal cans | Extremely slow decomposition | 1 million years (glass); 50-200 years (metal) | |
| Synthetic fabrics (polyester, nylon) | Extremely slow | 20-200 years | |
| Styrofoam and Bubble wrap | Does not decompose | Never (effectively permanent) |
Explanation of the Decomposition Process
When organic waste like vegetable peels and food scraps are buried in soil, they undergo a biological decomposition process. Microorganisms such as bacteria and fungi break down these organic substances into simpler compounds. This process releases nutrients back into the soil and is an essential part of the nutrient cycle.
Equation for decomposition:
$$ {C_6H_{12}O_6 \rightarrow CO_2 + H_2O + energy} $$
In contrast, non-biodegradable materials like plastics are resistant to microbial breakdown. They persist in the environment and can be broken down only by physical processes like heat and pressure over very long periods.
Conclusions
- Biodegradable materials decompose relatively quickly due to microbial activity.
- Non-biodegradable materials like plastics and synthetic fabrics do not break down easily and persist in the environment.
- Effective waste management requires understanding these differences to properly handle and dispose of various types of waste.
Questions and Answers
What types of waste materials decompose the fastest?
Organic materials like vegetable peels and food scraps decompose the fastest due to microbial action.
Why do non-biodegradable materials not decompose easily?
Non-biodegradable materials do not provide suitable substrates for microorganisms and hence are not broken down by biological processes.
What role does moisture play in the decomposition process?
Moisture is essential for microbial activity, as it enhances the breakdown of organic matter by providing a suitable environment for microorganisms to thrive.
What can we learn about waste management from this activity?
Proper segregation of waste into biodegradable and non-biodegradable categories is crucial for efficient waste management and environmental conservation.
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