Many things we normally throw away can be recycled (used
again), including paper, glass, metals, plastics, and BIODEGRADABLE waste such as vegetable peelings and cut grass. Recycling
saves natural resources, such as trees and crude oil. It can also save energy
as it often takes less energy to make a product from recycled materials than it
does to make the product from new materials. For example, 93 per cent more
energy is needed to extract aluminium from ore than to recycle
it.
Most rubbish is dumped in big pits called landfill sites. The pits
are lined with clay to prevent poisons leaking into the surrounding soil and
polluting water supplies. Pipes are inserted into the pit to collect and remove
poisonous methane gas. Unless we recycle more, we will run out of places to put
landfill sites.
Scrap steel is flattened or shredded, then melted in a furnace. The
molten steel is poured into moulds to make slabs of steel called billets. Once
solidified, the billets are reheated and rolled into thin sheets.
Steel sheets are used to make a range of products, such as food cans
and car parts. Steel is 100 per cent recyclable. This means that recycled steel
is exactly the same as the steel in the original material.
Before recycling, paper is sorted into different grades. It is then
mashed with water and chemicals to form a pulp. The pulp is cleaned (to remove
staples, glue, or ink) and sprayed onto flat screens. When dry, the paper is
used to make new products, such as newspapers.
Plastics such as polyethylene terephthalate (PET), used in fizzy
drinks bottles, can be recycled. This is because they are a kind of plastic
called a thermoplastic. When heated, the plastic melts and can be moulded into
a new shape. Only thermoplastics are recyclable. Thermosetting plastics burn
rather than melt when heated.
Materials from living things are usually biodegradable.
They break down into simpler substances, often with the help of
micro-organisms. Leaves biodegrade into compost and carbon dioxide, both of
which recycle in our environment. Most plastics are not biodegradable. They are
so different from natural materials that micro-organisms cannot digest
them.
Making compost is a good way of recycling biodegradable materials
that you would otherwise throw away. Vegetable peelings, sawdust, and grass
cuttings can all be layered in a large container. Over a few months,
micro-organisms will break down the biodegradable waste into compost. This
rich, dark material can be scattered over the soil to provide plants with extra
nutrients.
