What we throw away, why it matters and how to reduce, reuse, recycle and dispose of it safely.
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Waste is any material we discard because it has no further use for us. Biodegradable waste (vegetable peels, paper, cotton) is broken down by bacteria and fungi. Non-biodegradable waste (plastics, glass, metals) stays for a very long time. By state, waste is solid (garbage), liquid (sewage, industrial effluent) or gaseous (smoke). Special kinds are biomedical waste from hospitals, hazardous waste (batteries, chemicals) and e-waste (old phones, computers). Poor disposal pollutes soil, water and air, spreads disease and harms animals.
Differentiate biodegradable and non-biodegradable waste with two examples each.
Biodegradable breaks down naturally: vegetable peels, paper. Non-biodegradable does not: plastic bags, glass bottles.
Why is e-waste dangerous?
It contains toxic metals such as lead and mercury, which pollute soil and water if dumped.
Give two harmful effects of dumping waste in the open.
Any two: bad smell, breeding of flies and rats, disease, pollution of soil and water, blocked drains.
Reduce waste (buy only what you need, avoid single-use plastic), reuse what you can (cloth bags, glass jars, old clothes) and recycle (paper, glass, metal and some plastics are processed into new things). Segregate at source into wet or organic waste, dry or recyclable waste and hazardous waste; each goes by a different route. Wet waste can be composted, or turned into manure by earthworms in vermicomposting. Dry waste goes to recyclers. Sanitary landfills bury what cannot be recycled, and incineration burns waste at high temperature with controlled emissions.
A family of 4 makes 0.5 kg of waste per person per day. How much in a year of 365 days?
4 × 0.5 × 365 = 730 kg.
If 60% of that is organic, how much can be composted?
0.6 × 730 = 438 kg.
Why is segregation at the source important?
Mixed waste is hard and unsafe to recycle; separate streams let organic waste become compost and dry waste be recycled.
Sewage is used water from homes and industries with human waste, soap and chemicals. Untreated sewage spreads cholera and typhoid and pollutes rivers. At a sewage treatment plant, primary treatment removes large solids by screening and settling; secondary treatment uses bacteria to break down organic matter in the water; tertiary treatment may disinfect the water with chlorine or ultraviolet light before release. The solid sludge can be digested to produce biogas.
What happens in primary treatment of sewage?
Large solids and grit are removed by screening and settling.
Which organisms do the work in secondary treatment?
Bacteria (and other microbes) that break down the organic matter.
Name one useful product obtained from sewage sludge.
Biogas (methane), and after digestion, manure.
1. What is waste?
2. Give two examples of non-biodegradable waste.
3. What are the three Rs?
4. What is composting?
5. What is vermicomposting?
6. Why should used batteries not be thrown with kitchen waste?
7. What is biomedical waste? Give an example.
8. A school makes 12 kg of waste a day, 5 days a week. How much in 40 weeks?
9. Why is untreated sewage harmful?
10. Suggest three ways a household can reduce waste.