Class 6 Science Notes Chapter 16 (Chapter 16) – Examplar Problem Book

Detailed Notes with MCQs of Chapter 16, 'Garbage In, Garbage Out'. This is an important topic, not just for your exams but for understanding our environment. Pay close attention as we break down the key concepts for your government exam preparation.

Chapter 16: Garbage In, Garbage Out - Detailed Notes

1. What is Garbage?

• Garbage refers to unwanted or useless waste materials generated from various human activities.
• Sources: Households (kitchen waste, packaging, old clothes), Schools, Offices, Shops, Industries (chemicals, scrap metal), Agriculture (crop residues, animal waste), Hospitals (medical waste - needs special handling).

2. Types of Waste:
It's crucial to differentiate between the types of waste for proper management:

• Biodegradable Waste:
  • Definition: Waste materials that can be broken down (decomposed) into simpler, harmless substances by the action of microorganisms (like bacteria, fungi).
  • Examples: Fruit and vegetable peels, leftover food, paper, wood, cotton cloth, plant leaves, animal dung.
  • These wastes eventually rot and become part of the soil.
• Non-biodegradable Waste:
  • Definition: Waste materials that cannot be broken down by microorganisms or take an extremely long time (hundreds or thousands of years) to decompose.
  • Examples: Plastics (bags, bottles, toys), glass, metals (cans, foils), synthetic fibres, thermocol.
  • These wastes persist in the environment, causing pollution.

3. Dealing with Garbage - Waste Management Methods:

• Segregation: The first and most important step is separating waste into biodegradable and non-biodegradable at the source (homes, schools, etc.). Often uses different coloured bins (e.g., Green for biodegradable, Blue for recyclable non-biodegradable).
• Landfills:
  • Large, low-lying open areas where garbage collected from a city or town is dumped and covered with soil.
  • Issues: Takes up large amounts of land, can cause soil and water pollution (leachate), emits harmful gases (methane), often unsightly and smelly. Useful items also get buried.
• Composting:
  • Definition: A natural process of converting biodegradable waste (like kitchen scraps, leaves) into nutrient-rich manure called compost.
  • Method: Biodegradable waste is collected in a pit or heap, sometimes layered with soil or cow dung, kept moist, and allowed to decompose over several weeks/months by microorganisms.
  • Benefits: Reduces the volume of garbage going to landfills, produces valuable manure for plants, environmentally friendly.
• Vermicomposting:
  • Definition: A specific type of composting using earthworms, typically Redworms, to accelerate the decomposition of biodegradable waste.
  • Process: Redworms consume the organic waste and excrete castings, which form high-quality manure called vermicompost.
  • Key Points about Redworms: They don't have teeth; they have a structure called a 'gizzard' that helps grind food. They need a moist environment, not too hot or too cold.
  • What NOT to put in a vermicompost pit: Oily/greasy food, salty/pickled items, meat, fish, dairy products, diseased plants, plastics, glass, metals.
  • Benefits: Faster than regular composting, produces very rich manure, worms multiply, helping process more waste.
• Recycling:
  • Definition: Processing waste materials to create new products.
  • Materials Commonly Recycled: Paper, plastics, glass, metals.
  • Paper Recycling: Old paper is soaked, cleaned, pulped (made into a paste), spread, pressed, and dried to make new paper. Saves trees and energy.
  • Benefits: Conserves natural resources (trees, ores, petroleum), saves energy, reduces pollution (air, water, land), reduces the need for landfills.
• Reuse:
  • Using items again for their original purpose or a new purpose, instead of throwing them away.
  • Examples: Using glass jars for storage, repairing clothes or furniture, using old envelopes for rough work, using both sides of a paper.
• Reduce:
  • Minimizing the amount of waste generated in the first place. This is the most effective approach.
  • Examples: Buying items with less packaging, carrying your own cloth bag for shopping, avoiding single-use items (disposable plates, cups), planning meals to avoid food waste.
• Refuse:
  • Saying 'no' to things you don't need, especially single-use items like extra plastic bags, straws, or promotional freebies you won't use.

4. Plastics - A Major Concern:

• Boon: Lightweight, strong, durable, waterproof, versatile, relatively cheap. Used in countless applications.
• Curse (Problems):
  • Non-biodegradable: Persist in the environment for centuries.
  • Pollution: Litter streets, clog drains (leading to flooding), pollute soil and water bodies.
  • Harm to Animals: Animals may ingest plastic bags or get entangled in plastic waste, leading to injury or death.
  • Burning Hazard: Burning plastics releases toxic fumes (dioxins, furans) that cause air pollution and health problems.
  • Difficult to Recycle: Not all types of plastics are easily recyclable.
• Managing Plastic Waste:
  • Reduce usage drastically (carry own bags, water bottles).
  • Reuse plastic containers whenever possible.
  • Recycle plastics that can be recycled (check local guidelines).
  • Do Not Burn plastic waste.
  • Dispose of plastics responsibly; don't litter.
  • Support initiatives finding alternatives to plastic.

5. The Waste Management Hierarchy (The 3 R's and beyond):

• The most preferred approach is Reduce, followed by Reuse, then Recycle. Disposal (like landfilling) is the least preferred option. Sometimes Refuse and Repurpose (using something for a completely different function) are also included.

6. Our Role:

• Practice segregation of waste at home and school.
• Minimize waste generation by following the 3 R's.
• Participate in community cleanliness drives.
• Educate others about responsible waste management.
• Do not litter public places.
• Dispose of waste in designated bins only.

Multiple Choice Questions (MCQs)

Here are 10 MCQs based on the chapter to test your understanding:

1. Which of the following items is non-biodegradable?
   (a) Paper bag
   (b) Cotton cloth
   (c) Plastic bottle
   (d) Leftover food

2. The process of converting plant and animal waste into manure using specific earthworms is called:
   (a) Landfilling
   (b) Composting
   (c) Recycling
   (d) Vermicomposting

3. Which type of earthworm is commonly used for vermicomposting?
   (a) Tapeworms
   (b) Redworms
   (c) Roundworms
   (d) Flatworms

4. Which of the following should NOT be added to a vermicomposting pit?
   (a) Vegetable peels
   (b) Fruit waste
   (c) Dried leaves
   (d) Pickles and oily food

5. Burning which type of waste material produces harmful gases?
   (a) Paper
   (b) Dried leaves
   (c) Plastics
   (d) Kitchen waste

6. Large low-lying open areas used to dump garbage are known as:
   (a) Compost pits
   (b) Recycling centres
   (c) Landfills
   (d) Vermicompost units

7. Which of the '3 R's' is considered the most effective way to manage waste?
   (a) Recycle
   (b) Reuse
   (c) Reduce
   (d) Repurpose

8. Making new paper from old newspapers is an example of:
   (a) Reusing
   (b) Reducing
   (c) Recycling
   (d) Composting

9. Why is segregating waste into biodegradable and non-biodegradable important?
   (a) It makes the garbage look neat.
   (b) It allows for proper composting and recycling.
   (c) It reduces the total amount of garbage.
   (d) It is required only in villages.

10. What is the main environmental problem associated with plastics?
    (a) They are very heavy.
    (b) They rot very quickly.
    (c) They are non-biodegradable and cause pollution.
    (d) They dissolve easily in water.

Answer Key for MCQs:

1. (c)
2. (d)
3. (b)
4. (d)
5. (c)
6. (c)
7. (c)
8. (c)
9. (b)
10. (c)

Study these notes carefully. Understanding waste management is crucial for a cleaner environment and often features in competitive exams. Let me know if any part needs further clarification!