Managing our garbage

More garbage than ever

Our grandparents threw away very little. Food came loose, bags were made of cloth, and things were mended rather than replaced. Today much more is packed in plastic and paper, and many things are used once and thrown away.

These changes in lifestyle have greatly increased the amount of garbage we make. A town's waste has to go somewhere. If it is simply dumped, it pollutes the land, the water and the air.

Reduce, reuse, recycle

There are three ways to cut down our garbage. The order matters: the first is the best.

1. Reduce. Use less in the first place. Carry a cloth bag for shopping. Refuse items wrapped in many layers of packing. Switch off what you do not need.
2. Reuse. Use a thing again before throwing it away. Glass jars can store food. Old clothes can become dusters.
3. Recycle. Send paper, plastic, glass and metal to be made into new things. Recycling needs energy, but it saves raw materials.

Sorting waste at home

Recycling is easy only when the waste is sorted where it is made. Many towns ask each home to keep two bins.

• The green bin is for wet waste: peels, left-over food, tea leaves and garden waste. It is biodegradable.
• The blue bin is for dry waste: plastic, glass, metal, and paper and cardboard. Kept clean and dry, it can be recycled.

When the two are mixed, the wet waste rots on the dry, and both are spoiled.

With the starting values, the wet bin gets $6$ kg and the dry bin $4.5$ kg, so the wet share is about $57$ %. Try a family that eats more packed food: more plastic, less wet waste.

Where the waste goes

• Composting. Wet waste is left in a pit or a heap, where decomposers turn it into compost, a rich manure for plants. Only part of the mass remains; the rest goes into the air as gases and water vapour.
• Recycling. Clean dry waste is collected, sorted and made into new products.
• Landfills. Waste that cannot be used is buried in low-lying land. A landfill fills up, and non-biodegradable waste stays in it for centuries.
• Burning. Burning garbage in the open releases harmful gases and smoke. Plastic is especially harmful to burn.

Every choice has a cost

Some years ago, plastic cups on trains were replaced by kulhads, cups of baked clay. Kulhads are biodegradable, so it seemed a good idea.

But think of the numbers. Millions of passengers drink tea every day. Making millions of kulhads would use up a great deal of fertile topsoil, which takes a very long time to form. So the plan was not a lasting answer.

Paper cups and washable cups each have costs too. There is no perfect choice. We have to weigh the harm each one does, and choose the least.

Try it in Python

The program adds up a family's waste for a week, bin by bin.

You should see $8.5$ kg in the wet bin, $3.9$ kg in the dry bin, and a wet share of $69$ %.

Practise with new numbers

Common mistakes

• Putting recycling first. Reducing comes first: waste that is never made needs no handling.
• Mixing wet and dry waste. Mixed waste is hard to compost and hard to recycle.
• Thinking every biodegradable choice is green. Kulhads use up fertile topsoil.
• Burning plastic to get rid of it. It releases harmful gases into the air.

Remember these

• Our lifestyle makes far more garbage than before, much of it packaging and disposable items.
• Reduce, reuse, recycle, in that order.
• Green bin: wet, biodegradable waste for compost. Blue bin: dry waste for recycling.
• Every way of dealing with waste has a cost; choose the one that does the least harm.

Check yourself

Try each one on your own first. If you are stuck, open a hint. Then check with Show the answer.

1. Which is the best of the three Rs, and why?

2. Which bin should an empty glass jar go into?

3. Why were kulhads not a lasting answer for tea on trains?

4. A family of $4$ throws away $300$ g of garbage per person a day. How many kilograms is that in a week?

5. Why should we not burn plastic waste in the open?