Waste Management — I Impact of Waste Accumulation — Question 21
Back to all questionsDelhi has a massive municipal solid waste management problem with the massive landfills at Ghazipur, Okhla and Bhalswa at the centre of the issue. Delhi generates 11,332 tonnes of solid waste every day according to the latest estimate by the Municipal Corporation of Delhi (MCD), even as the civic body said that 4,360 tonnes of this garbage ends up at the city's three landfill sites.
(Source: 22nd February 2023, Hindustan Times)
(a) What is the cause for the issue mentioned above?
(b) Mention the three different methods of treating waste of the given type?
(c) How can an individual reduce waste generation?
(d) How can Delhi manage its waste following the example of Indore?
(a) The cause for the massive municipal solid waste management problem in Delhi is excessive generation of solid waste combined with inadequate waste processing and disposal systems.
(b) Three different methods of treating municipal solid waste like the type generated in Delhi are:
- Composting: Organic waste such as food scraps and garden waste can be biologically decomposed to form compost, which can be used as a natural fertilizer.
- Incineration: This involves burning waste at high temperatures to reduce its volume and sometimes generate electricity. However, it must be done in a controlled environment to avoid air pollution.
- Recycling and Resource Recovery: Waste materials like plastic, paper, glass, and metals can be sorted and processed to be reused in manufacturing new products, reducing the need for raw materials and saving energy.
(c) An individual can reduce waste generation in the following ways:
- Use reusable items like cloth bags, metal bottles, and containers instead of single-use plastics.
- Avoid the use-and-throw habit by repairing and reusing items instead of discarding them quickly.
- Segregate waste at home into dry, wet, and hazardous categories to help in proper recycling and disposal.
- Compost kitchen waste like fruit peels and vegetable scraps at home.
- Buy only what is needed to avoid wastage of food and other goods.
(d) Delhi can manage its waste more effectively by learning from Indore, which has been ranked as India’s cleanest city for several years. Here’s how Delhi can follow Indore’s example:
- Door-to-door waste collection: Like Indore, Delhi can ensure that waste is collected daily from each household and shop to prevent roadside dumping.
- Waste segregation at source: Indore citizens separate dry and wet waste before disposal. Delhi can promote awareness and strict rules to do the same.
- Use of composting and recycling plants: Indore processes almost all of its waste. Delhi can increase its number of compost and recycling centers to reduce landfill use.
- Strict monitoring and fines: Indore uses CCTV and teams to check for violations. Delhi can adopt similar systems to encourage discipline.
- Public participation: Indore succeeded due to citizen involvement. Delhi can launch awareness drives and school programs to promote cleanliness as everyone’s responsibility.
Chapter Overview: Waste Management
Waste Management is the collection, transport, processing, recycling, and disposal of waste materials. This chapter covers the classification of waste into biodegradable and non-biodegradable categories, solid waste management methods (composting, incineration, sanitary landfills), the three stages of sewage treatment (primary, secondary, tertiary), and the management of special waste categories including biomedical waste, electronic waste (e-waste), and nuclear waste. The 3Rs principle (Reduce, Reuse, Recycle) forms the foundation of sustainable waste management. India generates over 62 million tonnes of municipal solid waste annually, of which only about 20% is processed. The Swachh Bharat Abhiyan launched in 2014 aims to improve waste management across the country. Students must understand the differences between waste disposal methods, their advantages and limitations, and be able to suggest appropriate management strategies for different types of waste. The waste-to-energy concept, where non-recyclable waste is converted into electricity or fuel, is an emerging area of focus.
Key Definitions & Concepts
| Term | Definition |
|---|---|
| Biodegradable Waste | Waste that can be decomposed by microorganisms into simpler, non-toxic substances (e.g., food scraps, paper, dead leaves, animal dung) |
| Non-biodegradable Waste | Waste that cannot be broken down by natural biological processes; persists for hundreds of years (e.g., plastic, glass, metals, Styrofoam) |
| Composting | Aerobic decomposition of organic waste by microorganisms to produce humus (nutrient-rich fertiliser) |
| Vermicomposting | Composting using earthworms (Eisenia fetida) to accelerate the decomposition of organic matter |
| Incineration | Controlled burning of waste at 800–1000°C in specially designed furnaces; reduces volume by up to 90% |
| Sanitary Landfill | Engineered waste disposal site with impermeable liner, leachate collection system, daily soil cover, and gas venting |
| Leachate | Contaminated liquid that drains from a landfill, containing dissolved organic and inorganic pollutants |
| BOD | Biochemical Oxygen Demand – the amount of dissolved oxygen needed by aerobic organisms to decompose organic matter in water; higher BOD indicates greater pollution |
| E-waste | Discarded electronic devices containing hazardous materials (lead, mercury, cadmium) that require specialised recycling |
| 3Rs | Reduce (minimise waste), Reuse (use items again), Recycle (reprocess into new products) – the hierarchy of sustainable waste management |
| Waste-to-Energy | Conversion of non-recyclable waste into electricity, heat, or fuel through incineration with energy recovery, gasification, or pyrolysis |
Must-Know Concepts
- Biodegradable waste decomposes naturally (days to months); non-biodegradable waste persists for centuries
- 3Rs hierarchy: Reduce > Reuse > Recycle (prevention is better than treatment)
- Composting is suitable only for organic/biodegradable waste; produces humus used as fertiliser
- Incineration reduces volume by 90% and is essential for biomedical and hazardous waste
- Sanitary landfill key features: impermeable liner + leachate collection + daily soil cover + gas venting
- Sewage treatment has three stages: Primary (physical) → Secondary (biological) → Tertiary (chemical)
- Secondary treatment reduces BOD by 85–90% using aerobic bacteria in aeration tanks
- Biomedical waste uses colour-coded bins: Yellow, Red, Blue, White (puncture-proof for sharps)
- E-waste contains heavy metals (lead, mercury, cadmium); managed through EPR and authorised recyclers
- Nuclear waste management: vitrification (converting to glass), deep geological repositories, lead-lined containers
- India generates 62 million tonnes of MSW annually; is the 3rd largest e-waste producer globally
Biodegradable vs Non-biodegradable Waste
| Feature | Biodegradable Waste | Non-biodegradable Waste |
|---|---|---|
| Decomposition | Broken down by microorganisms | Cannot be decomposed naturally |
| Time | Days to months | Hundreds to thousands of years |
| Examples | Vegetable peels, paper, cow dung | Plastic, glass, aluminium cans |
| Management | Composting, vermicomposting, biogas | Recycling, incineration, sanitary landfill |
Sewage Treatment Stages
| Stage | Type | Process | What is Removed |
|---|---|---|---|
| Primary | Physical | Screening, grit removal, sedimentation | Large debris, sand, suspended solids |
| Secondary | Biological | Aeration with activated sludge (bacteria) | Dissolved organic matter (BOD reduced 85–90%) |
| Tertiary | Chemical | Chlorination, UV treatment, filtration | Pathogens, nutrients (N, P), colour, odour |
Important Diagrams to Practice
- Flow chart of sewage treatment (Primary → Secondary → Tertiary)
- Cross-section of a sanitary landfill showing liner, waste layers, soil cover, leachate collection, gas venting
- Waste management hierarchy pyramid (Prevention > Reuse > Recycling > Recovery > Disposal)
- Colour-coded biomedical waste bins with waste categories
Common Mistakes
- Confusing biodegradable with recyclable (paper is both; glass is recyclable but not biodegradable)
- Swapping secondary (biological) and tertiary (chemical) stages of sewage treatment
- Forgetting to mention the impermeable liner as the key feature of a sanitary landfill
- Calling open burning “incineration” (incineration is controlled burning in a furnace with emission controls)
- Not providing specific Indian examples when asked (Okhla WtE plant, E-Waste Rules 2016, Swachh Bharat)
Board Exam Tips
- Use comparison tables for 5-mark answers (biodegradable vs non-biodegradable, composting vs incineration vs landfill)
- Always define the term first, then explain with examples
- For sewage treatment, draw a flow diagram if asked for explanation
- Mention the 3Rs in order: Reduce → Reuse → Recycle with one example each
- Know the colour-coded bins for biomedical waste (Yellow, Red, Blue, White)