Plastics recycling is in the spotlight as it has the potential to dramatically minimize waste by repeatedly reusing materials. In fact, there is so much written that the public are more confused than ever. I hear many questions on this and if you’ve been wondering about any of these topics, then you can finally get a simple explanation from an expert.
Here are the main questions that come up:
· Can plastics be recycled?
· Is chemical recycling of plastics the way forward?
· s recycling plastics good for the environment?
· Are plastics really recycled?
· Why is so little plastic recycled now?
Those are all great questions, so let’s go through them one by one. Before we get started, I should explain that mechanical recycling means collecting plastic, washing, grinding it up and remelting it into a new part. That is very widespread proven technology. Chemical recycling is in its infancy and that is where chemistry is used to take the plastic back to its original small molecules (called monomers), purify them and reassemble the plastic by re-polymerization. This page refers to mechanical recycling, unless stated otherwise.
The answer is yes! It is a scientific fact that plastics can be recycled. Just as you can remelt wax and make a new candle, plastics can also be remelted to make new parts. Recycling plastics is not only possible but proven and yet I still see people claiming that they are not recyclable. How that can that be? There are two reasons that some people make that claim:
They are not scientists or industry experts, so they don’t know what they are talking about – or…
They don’t understand how the English language works
Let me explain that in more detail. Some people claim that because some plastics are not recycled in certain locations, that makes them unrecyclable. But that’s not correct, according to science or according to the dictionary. Here is an analogy…
I have a ball.
The ball is kickable.
I choose not to kick the ball.
The ball is unkicked.
However, it remains kickable.
By the same token –
We have some plastic.
The plastic is recyclable.
The local municipality chooses not to recycle the plastic.
The plastic is unrecycled.
However, it remains recyclable.
Dictionary definition: re·cy·cla·ble /rēˈsīk(ə)ləb(ə)l/
able to be recycled.
a substance or object that can be recycled.
“the city could sell recyclables at a profit”
(Definition from Oxford Languages)
My apologies for having to explain something so basic to you, but it is amazing to see people argue about this online, so I wanted to make sure it was put to rest.
Plastics can and are recycled. You can simply remelt them and form a new item.
Just after I wrote this Greenpeace sued Walmart for saying plastics are recycleable even though they may not always get recycled. Apparently, they didn’t check a dictionary.
Yes – we can be sure that mechanically recycling plastic (remelting it) is good because in depth, peer-reviewed scientific studies conclusively show that recycling plastics places less burden on the environment than using new plastic does. Recycling plastic saves material, saves energy, reduces waste and so on. For example, it has been estimated that mechanically recycled plastic requires only a tenth as much energy to make as virgin plastic. That means less carbon dioxide emissions in addition to the energy saving (usually a combination of coal, gas, oil, nuclear and so on).
Source: Wong, C. (2009), “A Study of Plastic Recycling Supply Chain 2010 A Study of Plastic Recycling Supply Chain”
I have seen articles highlighting the energy and oil used to make plastic, but focusing on the energy used to make plastics out of context presents a misleading picture. It is worth remembering that although all materials need energy for their manufacture, plastics require far less than other materials like metals, glass or even cotton. While recycling plastic is green, replacing it usually does more harm.
Recycling plastics is good for the environment.
Yes, several tens of millions of tons of plastic are mechanically recycled every year and recycling rates have increased substantially over recent decades. Mechanical recycling means collecting the plastic, grinding it up and remelting it into new shapes. It is the simplest and most common recycling method and applies to most of the common plastics we use such as polyethylene, polypropylene, PET, polystyrene, SAN, ABS, PVC polycarbonate and nylons. If we look at the pie chart of the most common plastics, all of them (~90%) are easy to recycle by melting except for polyurethane (PU) and some of the “others”. People ask whether our normal plastics can be recycled and the clear answer is yes.
You may have heard of chemical recycling because it is attracting a lot of press. That is being developed for the ~10% of plastics mentioned above (some polyurethanes, epoxies and other thermoset materials) that cannot be melted and recycled the normal way. Chemical recycling requires more energy, more chemicals and more investment to do. It does work, but it is only needed for a small fraction of plastics and it may turn out not to be green or viable on a large scale. Hopefully it will develop to address that small fraction of hard to recycle plastics.
In the USA people complain that only 9% of plastics get recycled and I have to agree that the number is far too low. Many other countries do far better. A list of top five best recycling countries reveals: Germany 56%, Austria 54%, South Korea 54%, Wales 52% and Switzerland 50%. Note that Germany was 3% in 1991 and are now over 56%, so large improvements have been achieved there and the US could do the same if they choose to. How much recycling capacity is there? A recent report revealed that Europe has 8.5 million tons of installed recycling capacity as of 2020. In Norway the use a deposit scheme which is so effective that 97% of PET bottles are returned and recycled several times. Other countries have followed this highly successful model and have also achieved >90% return rates.
Yes, plastics are widely recycled in huge amounts, although there is much room for improvement.
There are several factors that have held back recycling rates. I will briefly mention the main reasons plastics are not recycled more.
Plastic collection for recycling
Plastics need to be collected, cleaned, sorted and ground up before they can be recycled. One cannot simply throw mixed dirty plastic into a machine and get good product out. Investment is needed to make this all happen all across every country.
Mixed plastics and recycling
It is possible to melt several plastics together and make parts with the mixture but the mechanical properties such as the strength and resistance to impact will not be as good as if each plastic is sorted and remelted separately. The same applied to metals and glasses. It is important to separate steel from aluminium, copper and so on.
Recycling black and coloured plastic
The public have been told that we cannot recycle coloured plastic, but it turns out that’s just another myth about plastics. Coloured plastics can be melted and reshaped just the same as colourless plastics are. So, where did this myth come from?
In the past, optical sorting machines were unable to correctly identify black plastics for sorting. That problem was solved by changing the black pigment normally used (carbon black) to a different one that doesn’t confuse the sorting machines.
You may have seen that Sprite have moved away from their iconic green PET bottles in favour of new colourless PET bottles. Both bottles recycle the same but clear recycled PET is more in demand, so they decided it made more sense to make the change.
The economics of plastic recycling
We have seen that technically speaking, plastics can be recycled using existing technology, but what about the economics? Does it make commercial sense to recycle plastics? The answer is sometimes it does and sometimes it doesn’t. The price of recycled plastic varies, so that one day recycling is profitable and the next it is not. If there was money to be made recycling plastics, then there would be a thriving business, but we know that is not the case. Recently, large companies like Nesté and Unilever have signed pledges to buy huge volumes of recycled plastic at guaranteed prices and that has enabled recycling companies to spring up to meet the stable demand.
Colour, odor, consistency and supply
Trace impurities in the recycled plastic can lead to off smells which must be trapped or neutralized using additives. Whereas virgin plastics are usually white or colourless, recycled plastics are often grey and that color varies over time. Brand owners ask for recycled plastic but may not realize that they will be unable to make attractive looking products with their brand colours. Adding vastly more pigment may help, but in some instances, it is simply impossible to achieve the desired colour no matter how much extra pigment is used.
Another factor is supply. If you are a brand owner and want to launch a product range of shampoo bottles made from recycled plastic, you need to be 100% certain that the recycled plastic will be available every single day the product is in production. Factory shutdowns due to lack of raw materials are expensive and unacceptable. Consistency of supply is vital but so is consistency of the plastic material quality. Virgin plastic is pure and consistent whereas recycled plastics need to be cleaned and may vary over time depending on the sources. The lack of consistency presents a problem for the manufacturer trying to make parts. They may have more rejects and waste, plus they will need to adjust the equipment to account for any changes.
For more plastic to be recycled we need to ensure that there is a stable, attractive market for it and continue to make technical advances.
Hopefully this has answered your questions. We know from lifecycle analyses that plastics are some of the greenest materials we have, and recycling plastics makes them even greener. For example, there are 24 LCA studies on bags and every single one shows that PE plastic is a better choice than paper, cotton or degradable plastic. The same for bank notes, straws and textiles.
Most of the common plastics we use today can be recycled several times which reduces use of virgin material and saves energy too. Unfortunately, there is a perception that we should move away from plastic and towards metal and glass, in part because those materials are presently recycled at a higher rate in the US. However, that is backward thinking. Why choose metal and glass, two materials which are terrible for the environment, and use them again and again which means burning through huge amounts of energy every time? Repeating a mistake does not make things better – it makes them worse. That’s an insane approach because we know that plastics take far less energy to make and to recycle.
To sum up – numerous scientific studies clearly indicate that:
· Plastics are often the greenest choice (as proven by LCA)
· Plastics are recyclable
· Plastics are recycled in large amounts today worldwide
· Plastic recycling rates are especially low in the US and improvements are needed
Finally, it could be worth asking why we’re worried about plastics recycling in the first place. It is because there is a perception that we are drowning in plastics and that something must be done immediately. However, once again, have been misled. Plastics represent a small fraction of overall waste. Other materials like food, paper/cardboard, building rubble, mineral tailings each generate far more waste than plastics do. For some reason, there is an obsessive focus on plastics, which means that we are spending 100% of our attention and money addressing a small subset of the waste problem. If we want to really make an impact, we can’t keep obsessing over plastics and ignoring the other 99% of waste.