Managing waste: biodegradable and non-biodegradable substances
Biodegradable waste is broken down by bacteria and other decomposers; non-biodegradable waste is not. Separating, composting, recycling and using less plastic reduce the harm.
Biodegradable vs non-biodegradable
Decomposers break things down with enzymes, and each enzyme acts only on certain substances. Their enzymes cannot act on most man-made materials such as plastic, so plastic stays.
Problems caused by garbage
- Open garbage heaps smell and attract flies, mosquitoes and rats, which spread disease.
- Plastic bags block drains, causing waterlogging in the rains.
- Cows and other animals that eat plastic bags fall sick.
- Plastic in rivers and the sea harms fish, turtles and birds.
- Some chemicals enter food chains and build up (biological magnification).
Solutions: what we can do
| Method | How it works | At home or in school |
|---|---|---|
| Separate the waste | Keep wet (biodegradable) and dry (non-biodegradable) waste apart | Two bins in the kitchen and the classroom |
| Compost | Decomposers turn wet waste into manure | A compost pit or pot for peels and leaves |
| Recycle | Paper, glass, metal and some plastics are made into new things | Give old newspapers, bottles and cans to the kabadiwala |
| Reduce and reuse | Use fewer throwaway things and reuse what we have | A cloth shopping bag, a steel tiffin and a refillable bottle |
| Choose better materials | Pick things that cause less harm | Paper or reusable cups instead of throwaway plastic cups |
Plastic cups, kulhads or paper cups?
Tea at busy stations was once served in throwaway plastic cups, which piled up as waste. Going back to clay kulhads seemed a good answer, since clay is natural. But making kulhads in very large numbers would use up the fertile top layer of soil. Paper cups, which are biodegradable, are a better choice. Every answer to the waste problem must be checked for its own side effects.
A steel tiffin, a cloth bag and a refillable water bottle in your school bag cut plastic waste every day. Vegetable peels from the kitchen can go into a compost pot that feeds a balcony tulsi or chilli plant.
2 marks: “What are biodegradable and non-biodegradable substances? Give two examples of each.” Biodegradable: broken down by decomposers, such as vegetable peels and paper. Non-biodegradable: not broken down by biological processes, such as plastic and glass.
3 marks: “Suggest three ways in which a family can reduce the problem of waste disposal at home.” Separate wet and dry waste; compost kitchen waste; carry cloth bags and reuse containers; give paper, glass and metal for recycling (any three).
2 marks: “A canteen is choosing between throwaway plastic cups, clay kulhads and paper cups. Which should it choose, and why?” Paper cups. Unlike plastic they are biodegradable, and unlike kulhads made in huge numbers, they do not use up fertile top soil.
Bio-yes: it goes back to nature. Bio-no: it stays and harms. Wet bin, dry bin, every day.