How is plastic recycled ?
Recycling is considered as one solution to the environmental impacts of our frantic production of consumer goods, and in particular plastic. Selective waste sorting is now inevitable in both homes and businesses.
Yet, despite the ubiquity of recycling in our lives, we rarely question how it works and what it implies.
How is plastic recycled? What is the real impact of the recycling industry? Read along to find out the answers to all these questions.
4 things to know about the plastic industry
The plastic production industry is exponentially growing
Despite rising public awareness on the environmental crisis since the 1990s, the production and consumption of plastic are still growing. Over the past 30 years, the consumption of plastic has quadrupled. This is partly due to the growth of emerging countries.
400 million tonnes of plastic were produced in 2020. If nothing is done, the global annual plastic production is projected to reach 600 million tonnes by 2050.
The plastic production industry is highly carbon intensive
3 to 4% of global greenhouse gas (GHG) emissions are related to plastic ( IEA, The Future of Petrochemicals). Producing plastic is indeed highly carbon intensive.
The plastic industry’s effects on the environment are catastrophic
In addition to its carbon-intensive manufacturing processes, the plastic industry has many other negative effects, as given below.
- Ocean dumping. Over 150 million tonnes of plastic have already been dumped into the oceans, and this is expected to rise to 300 million tonnes by 2050. In 2016, a report by the Ellen MacArthur Foundation warned that by 2050, the total plastic volume in oceans would exceed that of fish.
- Plastic decomposition can take up to hundreds of years. Indeed, 22% of global plastic waste escapes recycling channels. In addition, nearly a quarter of global plastic waste ends up in nature (open dumps, forests, aquatic areas, etc.). This plastic waste is likely to remain there for a very long time. For instance, it takes approximately 1,000 years for a single polystyrene strip to decompose, and 450 years for a plastic bag.
Is recycling the solution?
Moving away from plastic altogether requires significant adjustments, particularly in regards to packaging, accounting for over a third of total plastic use.
In the meantime, one solution that is often put forward is recycling, limiting the production of new plastic and ensuring that the existing plastic isn’t a threat to the environment.
How does the recycling process work? Are all types of plastic recyclable? Is recycling a viable alternative? All the answers to these questions are given below.
Which types of plastic can be recycled?
Contrary to what the use of the generic term “plastic” suggests, there are many different types of plastic with varying properties.
The difference between these types of plastic lies in their manufacture. Depending on how they are made, not all types of plastic can be recycled. For those that can, some are more easily recycled than others.
How is plastic made?
Because plastic can be made in different ways, not all types of plastic can be recycled.
Plastic is made from naphtha, a liquid produced from refined petroleum. When heated to a very high temperature before being cooled, the hydrocarbon molecules break up into elementary molecules. These are called monomers.
The monomer molecules then get polymerised (i.e. they link to each other), thus taking the form of granules, liquid or powder.
The polymers thus formed are mixed with other chemical substances (solvents, antioxidants, dyes) in order to acquire different properties depending on what they are intended for (weldability, transparency, impermeability).
Polymers can be sorted into two main families of plastic:
- Thermoplastics. These materials melt when heated and harden when cooled, but this is reversible. Once recycled, thermoplastic waste can be melted and solidified again to produce new plastic objects.
- Thermosets. These materials, on the other hand, gradually harden under the effect of heat. They then reach an irreversible solid state, which makes them almost impossible to recycle by traditional means.
Recyclable types of plastic are therefore almost exclusively thermoplastics (although depending on the recycling method, some thermosets may also be recycled, as we will see below). They can be divided into several categories.
Fully recyclable types of plastic
About 40% of the world’s plastic production can be recycled. These recyclable types of plastic include:
- Polyethylene terephthalate (PET), found in water bottles, soda bottles, fruit juice bottles, cooking oil bottles, etc.
- High density polyethylene (HDPE), found in shampoo and household product bottles, bottle caps, some toys, etc.
- Polypropylene (PP), found in medical equipment, furniture, etc.
Types of plastic that are more difficult to recycle
Plastic types that are less easily recycled account for 45% of the world’s production. These include:
- Polyvinyl chloride (PVC), found in construction materials (pipes), etc.
- Low density polyethylene (LDPE), found in flexible plastic packaging, etc.
- Polystyrene (PS), found in transport protection, yoghurt pots, etc.
Types of plastic that cannot be recycled
All other types of plastic cannot be recycled, representing 15% of the world’s total production. These include:
- Plastic types that are too thin or too light, such as packaging, plastic films, some very thin bags, etc.
- Some types of hard plastic, such as toys, dishes, etc.
How is plastic recycled?
The two plastic recycling methods
There are two ways to recycle plastic:
- Mechanical recycling. The plastic is crushed and transformed into flakes or granules, which are then used as recycled raw material. 99% of plastic types (mainly thermoplastics) are recycled using this process.
- Chemical recycling. This only concerns 1% of recycled materials. Chemical recycling mainly overcomes the limitations of mechanical methods by transforming materials that the latter cannot recycle, such as thermosets and certain thermoplastics.
Explanation: Chemical recycling creates new raw materials by modifying the chemical structure of recycled plastic material:
- By separating the polymers from their additives (this is dissolution), the polymers are “purified“;
- By separating the polymers from each other (depolymerisation), the polymer molecules become monomers once more.
Once these transformations are made, the newly created polymers or monomers may be used to manufacture new material.
The limits of recycling
There are several limits to recycling plastic, given below.
- Plastic cannot be recycled indefinitely. Indeed:
- As time goes by, recycled plastic loses quality. Indeed, its association with pollutants and chemicals, as well as its melting and solidification phases alter its aspect. For example, the plastic used for water bottles cannot be recycled over 7 times;
- It is often necessary to add blank plastic so that the material retains similar properties, thus limiting the impact of recycling;
- Compliance with selective waste sorting. Plastic waste is not always well sorted and collected. Even in Europe (one of the best examples in this regard), only 40% of thrown away plastic is recycled. The rest ends up either incinerated, buried or discarded in nature;
- The recycling industry isn’t sufficiently developed. Indeed, in 2019, the global recycled plastic production only represented 6% of total plastic production, according to an OECD report. The organisation advocates creating a genuine market for recycled plastics by:
- Increasing investments in the recycling industry;
- Setting minimum rates of incorporation of recycled material in the production of new plastic materials.
Recycling is a solution to the pollution caused by the plastic industry, but it is far from being enough. Indeed, some types of plastic are not recycled or are difficult to recycle. Realistically, only a small minority of recyclable materials are really recycled, a large proportion not being collected and even discarded in nature.
To limit this industry’s effects on global warming, we must consider reducing our own plastic consumption.
This process is essential for firms’ decarbonisation.
At carbometrix, decarbonisation options are systematically proposed in all our reports, based on the analysis of emissions across all emission scopes. Where relevant, carbometrix may recommend using more recycled materials such as recycled plastic. If you are interested in decarbonising your firm’s value chain, get in touch with us now! carbometrix can calculate your firm’s carbon footprint to help you find ways to better reduce your environmental impact!