⚡ Quick Revision : Classification & Impact
1. What is Waste?
Waste is any substance which is discarded after primary use, or is worthless, defective, and of no further use. In Biology, we classify waste based on its ability to decompose.
- ♻️ Biodegradable Waste: Waste that can be broken down into simpler, harmless substances by the action of micro-organisms (e.g., vegetable peels, paper, sewage).
- 🚫 Non-Biodegradable Waste: Waste that cannot be decomposed by biological processes (e.g., plastics, glass, DDT, heavy metals).
2. Sources of Waste
- Domestic Waste: Kitchen waste, plastic bags, and discarded electronics.
- Industrial Waste: Effluents, fly ash, and chemical residues.
- Agricultural Waste: Pesticides, animal dung, and crop residues.
- Biomedical Waste: Used syringes, cotton, and bandages from hospitals.
3. Impact of Waste Accumulation
| Type of Impact | Consequences |
|---|---|
| Public Health | Spread of diseases like Cholera and Plague; breeding of vectors. |
| Terrestrial Life | Soil pollution, loss of fertility, and poisoning of soil organisms. |
| Aquatic Life | Eutrophication and depletion of dissolved oxygen ($O_2$). |
Question: Why is the accumulation of non-biodegradable waste considered more dangerous?
Answer: Unlike organic waste, these materials persist in the environment for hundreds of years. They often enter the food chain, leading to Biomagnification, where toxins increase in concentration at each higher trophic level.
Biomagnification refers to the increase in toxin concentration up the food chain. Bioaccumulation is the buildup of a substance within a single organism's body over time.
⚡ Quick Revision : Disposal & The 5 Rs
1. Primary Stage: Segregation
The most important step in waste management is Segregation at Source. Waste should be separated into different bins to make processing easier:
- 🟢 Green Bin: Biodegradable/Organic waste (food, garden waste).
- 🔵 Blue Bin: Recyclable non-biodegradable waste (paper, plastic, metal).
- 🔴 Red Bin: Hazardous waste (batteries, chemicals, medical waste).
2. Methods of Safe Disposal
- A. Sanitary Landfills: Waste is dumped in low-lying areas and compacted with layers of soil to prevent odors and pests.
- B. Composting: Aerobic decomposition of organic waste by microbes to produce nutrient-rich Manure. Vermicomposting uses earthworms to speed up this process.
- C. Incineration: Burning waste at very high temperatures ($800°C$ to $1000°C$). This is primarily used for Biomedical Waste to kill pathogens.
3. The 5 Rs Hierarchy
Modern waste management follows a specific order of priority to reduce environmental footprints:
- Refuse: Say no to things you don't need (e.g., single-use plastics).
- Reduce: Minimize the amount of waste generated.
- Reuse: Use items multiple times before discarding.
- Repurpose: Use an item for a new purpose (Upcycling).
- Recycle: Reprocess waste materials into new products.
Question: Why is Incineration preferred for hospital waste but not for general household plastic?
Answer: Hospital waste contains highly infectious pathogens that are only killed at extreme temperatures. Burning household plastics (like PVC) can release toxic gases like Dioxins and Furans, which are carcinogenic and pollute the air.
Composting is a biological process using microbes/worms. Incineration is a thermal process using fire. Pyrolysis is decomposition by heat in the absence of oxygen.