Safe Disposal of Waste: Segregation, Dumping, Composting and the 3Rs (ICSE Class 10)
Updated 17 October 2026 · Draft, not yet fact-checked
Safe waste disposal begins with segregation at source into wet (biodegradable) waste in a green bin and dry (recyclable) waste in a blue bin, with hazardous waste kept apart. Sanitary landfills bury waste in lined pits, compacted and covered each day, and are sited far from cities. Composting turns biodegradable waste into nutrient-rich manure. The 3Rs reduce waste at source, reuse items without processing, and recycle materials into new products, saving resources, energy and landfill space.
Notice that segregation at source sends each bin to a different route: wet waste to compost, dry waste to recycling, hazardous waste kept apart.
Illustration drawn for QuestionBuddy.
Understand Segregation, Dumping, Composting and the 3Rs
1. Segregation.
- *Meaning:* separating waste at the source into different categories.
- *Common system:* wet (biodegradable) waste in a green bin and dry (non-biodegradable, recyclable) waste in a blue bin, with hazardous waste kept apart.
- *Benefits:* makes composting and recycling easier and reduces the waste sent to dumps.
2. Dumping and landfills.
- *Dumping:* depositing waste on land, usually in low-lying areas outside towns. Open dumping is unhygienic.
- *Sanitary landfill:* waste is spread in layers in a lined pit, compacted and covered with soil each day, which reduces smell, pests and pollution.
- *Why landfills are located far from cities:* the foul smell, flies and rats; the risk of disease; the danger of methane fires; contamination of groundwater by leachate; and the need for large areas of cheap land.
3. Composting.
- *Meaning:* the decomposition of biodegradable waste, such as kitchen and garden waste, by micro-organisms (and earthworms, in vermicomposting) into dark, nutrient-rich manure called compost.
- *Uses:* it turns waste into organic manure that improves soil fertility, texture and water-holding capacity; it reduces the use of chemical fertilisers; and it reduces the amount of waste sent to landfills.
4. The 3Rs.
- *Need:* conserve natural resources and energy, reduce pollution, save landfill space and lower the cost of waste disposal.
- Reduce: produce less waste in the first place: buy only what is needed, avoid wasting food, use cloth bags instead of polythene, choose products with less packaging, and repair rather than replace.
- Reuse: use an item again, for the same or a different purpose, without processing it: an empty can as a pen stand, glass jars for storage, old clothes as dusters, refilling bottles.
- Recycle: process waste materials to make new products: scrap paper into handmade or recycled paper, plastic bottles into fibres or new plastic goods, metal cans melted to make new metal items, glass melted to make new glass.
5. Making waste useful by sector.
- *Household:* kitchen waste into compost or biogas; old clothes donated or reused.
- *Industrial:* fly ash from power plants into bricks and cement; slag into road material; bagasse into paper.
- *Agricultural:* crop residues into fodder, compost, biogas or boards; dung into biogas and manure.
6. Reuse versus recycle. Reuse uses the item again as it is; recycle processes the material into something new. A jar used again for storage is reuse; a jar melted to make new glass is recycling.
Segregation, Dumping, Composting and the 3Rs: key facts
- Segregation
- Green bin: wet (biodegradable)
- Blue bin: dry (recyclable)
- Hazardous waste kept apart
- Makes composting and recycling easier
- Sanitary landfill
- Lined pit
- Layers compacted
- Covered with soil daily
- Sited away from cities: smell, pests, disease, methane fires, leachate, land need
- Composting
- Biodegradable waste
- Micro-organisms and earthworms
- Compost
- Improves fertility, texture, water-holding
- Cuts chemical fertiliser and landfill load
- 3Rs
Reduce produce less Reuse use again unprocessed Recycle process into new products - Waste into resources
Fly ash bricks and cement Slag road material Bagasse paper Crop residues fodder, compost, biogas, boards Dung biogas and manure
How to answer Segregation, Dumping, Composting and the 3Rs questions
Pick the right method for each type of waste and give the reason.
- 1Segregate first: wet and dry waste go to different bins.
- 2Send wet waste to composting (or biogas) and dry recyclables to recycling.
- 3Use a sanitary landfill only for what cannot be recycled or composted, and keep it far from cities for the stated reasons.
- 4For 3R questions, give an example and a benefit for each R.
- 5To tell reuse from recycle, ask whether the item is processed into something new.
Segregation, Dumping, Composting and the 3Rs in real life
The idea, met in an everyday situation. Answer the question in your own words, then compare with the model answer. The one-line hook is what to remember.
Two bins in a flat
Suppose a housing society gives each flat two bins and asks residents to put vegetable peels and leftovers in the green bin, and paper, plastic and metal cans in the blue bin.
State two benefits of this system for the society.
Try it first, then show the solutionSolution
- Wet waste can be composted into manure, and dry waste can be recycled.
- The amount of waste sent to the dump falls.
Answer: Easier composting and recycling, and less waste sent to dumps.
Memory hook: Green is wet; blue is dry.
A jar's three lives
Suppose a family stops buying small packs and buys one big pack instead, keeps the empty glass jar to store spices, and later hands the broken jar to a collector who sends it to a glassworks to be melted into new glass.
Identify the R used at each stage.
Try it first, then show the solutionSolution
- Buying one big pack instead of many small ones reduces waste.
- Keeping the jar for spices is reuse; melting it into new glass is recycling.
Answer: Reduce, reuse, recycle.
Memory hook: Less, again, new.
Tricks to remember Segregation, Dumping, Composting and the 3Rs
Short memory aids. Say each one aloud once, then use it on a question the same day.
Green wet, blue dry
Green bin for wet and biodegradable waste; blue bin for dry and recyclable waste.
Use it when: Segregation questions.
Less, again, new
Reduce means less, reuse means again, recycle means a new product.
Use it when: 3R definitions.
Smell, pests, fire, leachate, land
Five reasons why landfills lie far from cities.
Use it when: Reasons for the siting of landfills.
Segregation, Dumping, Composting and the 3Rs: solved examples
Ordered from board level to HOTS. Try each one before you open the solution.
Example 1: Segregation · 3 marks · Short answerBoard level
What is segregation of waste? Name the bins and the waste each takes.
Try it first, then show the solutionSolution
- Segregation is the separation of waste at the source into different categories.
- Green bin: wet (biodegradable) waste. Blue bin: dry (non-biodegradable, recyclable) waste.
- Hazardous waste is kept apart.
Answer: Separating waste at the source; green bin for wet waste, blue bin for dry waste.
Example 2: Define composting · 3 marks · Short answerBoard level
What is composting? State two uses of compost.
Try it first, then show the solutionSolution
- Composting is the decomposition of biodegradable waste by micro-organisms into dark, nutrient-rich manure called compost.
- Uses: it improves soil fertility, texture and water-holding capacity; it reduces the use of chemical fertilisers.
Answer: Decomposition of biodegradable waste into manure; improves soil and reduces chemical fertiliser.
Example 3: Siting of landfills · 4 marks · Short answerHarder board level
A city's residents object to a proposed landfill site at the edge of their colony. Explain four reasons why such sites are chosen far from settled areas.
Try it first, then show the solutionSolution
- The foul smell and the flies and rats would trouble residents.
- There is a risk of disease.
- Methane can catch fire.
- Leachate can contaminate groundwater, and a landfill needs a large area of cheap land.
Answer: Smell and pests, disease, methane fires, groundwater contamination by leachate, and large cheap land.
Example 4: Reuse or recycle · 4 marks · Short answerHarder board level
Classify each as reduce, reuse or recycle: (a) using a cloth bag instead of polythene, (b) using an empty can as a pen stand, (c) melting scrap metal cans to make new items, (d) refilling a bottle. Justify (b) and (c).
Try it first, then show the solutionSolution
- (a) Reduce. (b) Reuse. (c) Recycle. (d) Reuse.
- (b) is reuse because the can is used again without processing.
- (c) is recycling because the metal is processed into new items.
Answer: (a) Reduce (b) Reuse (c) Recycle (d) Reuse.
Example 5: Case: a sugar mill and a power plant · 5 marks · Case-basedHOTS / competency
A sugar mill is left with large piles of bagasse and a power plant with fly ash and slag. (a) Suggest one use for each. (b) State why using these wastes is better than dumping them. (c) Name the R this illustrates and explain it.
Try it first, then show the solutionSolution
- (a) Bagasse into paper; fly ash into bricks and cement; slag into road material.
- (b) It saves landfill space, conserves resources and energy, and lowers disposal costs.
- (c) Recycling (processing waste materials into new products).
Answer: (a) Bagasse: paper; fly ash: bricks; slag: roads (b) Saves land, resources and cost (c) Recycle.
Where students lose marks in Segregation, Dumping, Composting and the 3Rs
The slips examiners see most often, and what to write instead.
Mistake: Mixing up the bin colours
Green and blue are swapped.
Do this: Green for wet, blue for dry.
Usually costs: 1 mark.
Mistake: Confusing reuse and recycle
Both involve using something again.
Do this: Reuse: unchanged. Recycle: processed into new.
Usually costs: 1 mark.
Mistake: Only one reason for the landfill location
Only the smell is mentioned.
Do this: Give smell, pests, disease, methane fires, leachate, land.
Usually costs: 1 to 2 marks.
Mistake: Not giving an example for each R
Definitions are written without examples.
Do this: Give a definition and one example for each.
Usually costs: 1 mark.
Exam tips
- Link each type of waste to its best method: wet to compost, dry to recycling.
- For 3Rs, write a definition and an example for each R.
- Use the words segregation, sanitary landfill, leachate and compost.
- For 'how can waste be useful', name a waste and its use: fly ash to bricks, bagasse to paper.
Practice questions on Segregation, Dumping, Composting and the 3Rs
Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.
Q1 · 1 mark · MCQBoard level
Kitchen waste should be put in the:
(a) blue bin
(b) green bin
(c) hazardous bin
(d) either binHint
Wet waste.
Answer
(b) green bin.
Q2 · 1 mark · MCQBoard level
A sanitary landfill differs from open dumping because in it the waste is:
(a) burnt in the open
(b) compacted in a lined pit and covered with soil daily
(c) thrown into a river
(d) left in heapsHint
Lined pit.
Answer
(b) compacted in a lined pit and covered with soil daily.
Q3 · 3 marks · Short answerHarder board level
Explain how composting benefits (a) farmers and (b) the city's waste system.
Hint
Manure and landfill load.
Answer
(a) Compost is organic manure that improves soil fertility, texture and water-holding capacity and reduces the need for chemical fertilisers. (b) It reduces the amount of waste sent to landfills.
Q4 · 3 marks · Short answerHarder board level
State two differences between reuse and recycle, with an example of each.
Hint
Processing.
Answer
Reuse uses an item again without processing (a glass jar for storage); recycling processes the material into new products (scrap paper into recycled paper). Reuse keeps the item's form; recycling changes it.
Q5 · 1 mark · Assertion-reasonHarder board level
Assertion (A): In a sanitary landfill the compacted waste is covered with soil each day.
Reason (R): Covering reduces smell, pests and pollution.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is not the correct explanation of A.
(c) A is true but R is false.
(d) A is false but R is true.Hint
What does the daily soil cover do?
Answer
(a).
Q6 · 3 marks · Short answerHarder board level
Describe three ways in which a household can reduce its waste.
Hint
Buying, packaging, repair.
Answer
Buy only what is needed and avoid wasting food; use cloth bags instead of polythene and choose products with less packaging; repair items rather than replace them.
Q7 · 4 marks · Case-basedHOTS / competency
A town's open dump is full and the council proposes a sanitary landfill near a river for convenience. (a) Explain the objections. (b) Describe two ways in which the amount sent to the landfill can be reduced.
Hint
Leachate; compost and recycle.
Answer
(a) Leachate can contaminate the river and groundwater; a landfill brings smell, pests and disease, and methane fire risk, so it should be far from settlements. (b) Segregate waste and compost wet waste, and recycle dry waste such as paper, plastic, metal and glass.
Q8 · 5 marks · Case-basedHOTS / competency
An agricultural village burns its crop residues and wastes cow dung. (a) Name two harms of burning residues. (b) Suggest two better uses of residues and dung. (c) Which R does this illustrate?
Hint
Fodder, compost, biogas.
Answer
(a) Smoke and harmful gases pollute the air and cause respiratory illness. (b) Crop residues into fodder, compost, biogas or boards; dung into biogas and manure. (c) Recycling (making waste useful).
Test your recall
Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.
1.Which bin is for wet waste?Show answer
The green bin.
2.What is compost?Show answer
Dark, nutrient-rich manure made from biodegradable waste.
3.What are the 3Rs?Show answer
Reduce, reuse and recycle.
4.Name a use of fly ash.Show answer
Bricks and cement.
5.What happens to waste in a sanitary landfill each day?Show answer
It is compacted and covered with soil.
Segregation, Dumping, Composting and the 3Rs: frequently asked questions
Why is waste segregated?
To make composting and recycling easier and reduce what goes to dumps.
Why are landfills sited away from cities?
Because of smell, pests, disease, methane fires, groundwater contamination and need for land.
What is vermicomposting?
Composting in which earthworms help to decompose biodegradable waste.
What is the difference between reuse and recycle?
Reuse uses an item again unchanged; recycle processes it into a new product.