4.8 - Reuse & Recycling

Why we reduce, reuse and recycle

• Most manufactured goods come from raw materials taken from the Earth, which are in limited supply (finite), such as metal ores.
• Extracting raw materials is damaging and expensive:
  • Uses large amounts of energy to extract and process them, mostly from burning fossil fuels.
  • Damages the environment through quarrying and mining, which scar the landscape, destroy habitats, and produce waste.

Three ways to conserve raw materials

1. Reducing - Using less of a material in the first place, saving raw resources, energy, and environmental damage.
2. Reusing - Using a product again in its current form, requiring far less energy than recycling because it isn't broken down or reprocessed.
3. Recycling - Breaking down a used product into its raw material to make something new.

All three approaches conserve finite resources, save energy, and reduce waste sent to landfill.

The economic case

• Processes that use less energy cost less to run, especially for materials that are expensive to extract.
• Recycling is an industry that creates jobs in collecting, sorting, and reprocessing waste.
• Recycling isn't always worth doing: the cost of collecting and reprocessing must be weighed against the cost of making the material from scratch.

What decides whether recycling is worth it

Whether a material is worth recycling is judged by weighing several factors:

• Finite deposits - Recycling is most urgent for materials derived from limited resources, such as metal ores and crude oil.
• Amount available - Enough material must be discarded and collected to make industrial-scale recycling practical.
• Collection and sorting costs - Separating mixed waste into pure materials takes time, money, and energy.
• Purity - Contaminated materials that can't easily be cleaned can't be recycled economically.
• Energy use - The energy used in transport and reprocessing must be less than the energy needed to extract and refine new material.
• Demand - There must be an end market for the recycled material.
• Environmental impact - The recycling process itself must produce less environmental harm than producing new material.

PET drinks bottles reused and recycled

• Drinks bottles are commonly made from a polymer called PET.
• Used bottles can be dealt with in two ways:
  • Reuse - Used again without being broken down.
  • Recycling - Broken down and processed into new products.

Reusing a PET bottle

• Bottles can simply be refilled.
• Filled with water and left in sunlight, they can disinfect water for drinking, as UV light passes through the plastic and kills pathogens.
• Reusing uses less energy than recycling, as the plastic doesn't need to be melted.

Recycling a PET bottle

1. Plastic waste is sorted to separate PET from other plastics.
2. The PET is shredded into flakes and washed.
3. The flakes are melted down and reformed into new products, such as clothing fibres or packaging.

Why recycling PET is worth it

• Saves energy - Making PET from scratch requires crude oil and extensive processing; recycling uses up to 75% less energy.
• Conserves crude oil - About 2.4 dm³ of crude oil is saved for every kilogram of PET recycled.
• Reduces landfill - Keeps bulky, non-biodegradable waste out of landfill sites.