I learned this today. Glass and metal can be recycled indefinitely, but plastic can only be recycled once or twice and paper about 7 times.
Recycling has been around for as long as people have used resources. There is archaeological evidence of scrap bronze being collected and melted down again in Europe. In 1031, a paper shop in Japan sold repulped paper. In Britain, dustmen (the word is still used today and is equal to the American term garbageman) collected the dust and ash from wood and coal files to recycle into bricks. This type of recycling starts because there is an advantage of using recycled materials instead of fresh materials: usually the cost. After the Industrial Revolution, the need for metal increased. Scrap metal is always cheaper than metal ore and is easier to use, so railway companies used it in the 19th century and automobile companies used it in the 20th century. There was a whole industry devoted to finding and selling scrap metal.
The Second World War produced a spike in recycling because there was a huge need for metal and other resources. Also, people living in war affected countries couldn’t get access to enough food and other amenities, so they started to recycle their household waste.
Since World War 2, the type of recycling has changed. Before, people recycled because it was cheaper than using virgin resources. After World War 2, we have started to recycle because we don’t have enough resources. If we don’t reuse it, we will run out.
Currently, a lot of things are recycled, and the EU has set a goal of 50%. The UN’s 12th Sustainable Development Goal is “Responsible Consumption and Production”. They want to reduce global waste significantly by 2030.
There are two problems associated with recycling that I want to look at. The first is that materials like plastic and paper are not infinitely recyclable, and the second is that a lot of products mix materials.
Metals and glass can be recycled infinitely. When a metal is melted down and recast as something else, there is no loss of matter and there is no loss of quality. It is exactly the same. An aluminium drink can can be melted down and made into a new can within 60 days. Glass is mostly the same. It can be melted down and reblown with no loss. That is, as long as it is the same type of glass and the same color.
Paper can be recycled up to about 7 times. Paper is made of fiber. When it is recycled, it is shredded, pounded, soaked and then heated to make fibers for new paper. Each time the paper undergoes this process, the fibers get a little shorter, until they are too short to make paper. This happens after about 7 repeats. Then they are thrown away. The one good thing is that paper is biodegradable, within about a month. The problem is there are huge quantities of paper thrown away. About half of all the rubbish in landfills is paper.
Plastic can only be recycled once or twice. This is because plastics are made of long chains of atoms called polymers. They are long and arranged in patterns that make plastics strong, lightweight, and flexible. When the plastic is recycled, these polymer chains get shorter and the plastic loses some of its strength, lightweightness, and flexibility. To fix this, fresh plastic also has to be added into the recycled plastic. If plastic is recycled more than two or three times, it becomes unusable. This doesn’t mean we shouldn’t recycle plastic, but it does mean we should try to cut down on it. I’m sure you know that some plastics take thousands of years to biodegrade. Well, Styrofoam never biodegrades. Ever. It will still be here when the sun becomes a red dwarf.
The second problem is two materials that might be recyclable on their own are often sandwiched together. A coffee cup is a good example. It is made of paper, which could be recycled a few times, but it has a waxy plastic lining. This lining is extremely difficult to remove and is not really cost efficient, so most coffee cups are not recycled. A candy wrapper is similar. There is a wax layer for the label, a plastic wrapper, and a thin aluminium lining to keep the bar insulated against the heat. These layers are all but inseparable and hence they are not recycled.
So, (if you are like me) we think everything is recyclable and that recycling will save all of the world’s problems. The problem is that things like glass and metal are infinitely recyclable, but plastic and paper can only be recycled a few times. The only solution is to stop using plastic, but that is not easy. And this is what I learned today.
Photo by mali maeder: https://www.pexels.com/photo/assorted-plastic-bottles-802221/
Sources:
https://blog.nationalgeographic.org/2018/04/04/7-things-you-didnt-know-about-plastic-and-recycling/
https://en.wikipedia.org/wiki/Recycling
https://earth911.com/business-policy/how-many-times-recycled/
https://recyclenation.com/2017/06/how-many-times-can-recyclables-be-recycled/
https://www.economist.com/technology-quarterly/2007/06/09/the-truth-about-recycling
https://homeguides.sfgate.com/many-times-can-something-recycled-79191.html
https://stacker.com/stories/2682/how-long-it-takes-50-common-items-decompose