8 November 2022
by Stuart Patrick FIMMM

Getting into the mechanics of plastics recycling

What is the state of play of the UK mechanical plastics recycling market? Stuart Patrick FIMMM breaks it down for us.

Lots of different plastic bottles
© photka/Shutterstock

Several initiatives are needed to tackle climate change, and waste management and recycling are an integral part of the solution – the challenge being the quantity and quality of materials that are collected for recycling linked to the need to recover as much plastic from all waste streams as possible.

TOMRA Recycling Sorting, a division of the TOMRA Group, together with many other organisations, predicts that the amount of plastic waste produced globally is on track to almost triple by 2060, with around half ending up in landfills and less than a fifth recycled.

Mechanical recycling preserves the molecular structure of the plastic by mechanically crushing post-consumer waste and undergoing various processes to separate it by plastic type. It is the most developed recycling process, having been in operation for many years.

Non-mechanical/chemical recycling is also another rapidly developing area (see Materials World, July/August 2021, for a review on chemical recycling).

In mainland Europe, there is an increase in the amount of waste collected and a significant decrease in waste going to landfill, while incineration with energy recovery still plays a large part in handling plastic waste. This is considered safe in modern waste-to-energy plants that are run efficiently and certainly reduces on fossil fuel demand. However, when burning plastic and other waste, there is still the issue of CO2 generated and emitted in the process. This is the subject of much research into carbon capture, storage and utilisation processes for net-zero carbon reasons.

Recycling, meanwhile, will always face competition from ‘fresh’ virgin plastic – depending on market price fluctuations of oil and gas, and if the recycling process has sufficient availability of cost-appropriate feedstock.

The brief
According to the UK Government in their Research Briefing on Plastic Waste, as published in March 2022, 'In the UK, it is estimated that 5Mt of plastic is used every year, nearly half of which is packaging'. 

The government publishes regular statistics on the amount of plastic packaging produced and on its final treatment, although some of these statistics have been questioned for their accuracy both by the National Audit Office and WWF-UK.

To meet the UK Government’s net-zero targets, we are urged to reduce, reuse and recycle. The UK Government, under former Prime Minister Theresa May, had a strategic ambition to “work towards all plastic packaging placed on the market being recyclable, reusable or compostable by 2025”.

This followed on from, and was intended to support, commitments to leave the environment in a better condition for the next generation and, in particular:

  • An “ambition” of zero avoidable waste by 2050
  • A “target” of eliminating avoidable plastic waste by end of 2042

The devolved administrations in Scotland, Wales and Northern Ireland each have their own ambitions on plastic waste and plans to move towards a more circular economy.

In 2021, WRAP (the Waste Resources Action Programme), stated that an estimated 1.2Mt of the UK’s plastic packaging was recycled in 2020 – a fourfold increase from levels achieved in the early 2000s.

WRAP also sets out that UK local authorities are estimated to have collected 572,000t of plastic packaging for recycling from the household waste stream in 2018/19 – 4% higher than the amount collected in 2017/18.

The UK Government’s December 2018 Resources and Waste Strategy, meanwhile, contained a number of polices aimed at reducing plastic waste. A range of consultations have followed, both UK-wide or by devolved governments, that have covered:

  1. The introduction of a deposit return scheme (DRS) in England, Wales and Northern Ireland
  2. Reform of the UK packaging producer responsibility i.e. Extended Producer Responsibility (EPR)
  3. Introduction of the Plastic Packaging Tax 

However, for the purposes of this article, the most relevant issue is consistency in household and business recycling in England. Wales has undertaken its own separate consultation on business recycling.

Upping the ante
There is sufficient evidence to show that mechanically recycled plastic reduces the amount of waste sent to landfills and incinerators, conserves natural resources such as oil, gas and water, and has a considerable energy saving.

A recent Recycling Roadmap, published by the British Plastics Federation (BPF), highlights what the UK needs to achieve if it is to drastically reduce reliance on exporting plastic waste for recycling. With the right drivers in place, plastic recycled within UK facilities could increase 3.5 times by the year 2030.

The report also indicates a projected rapid increase in non-mechanical recycling to 300kt, with the total effect of all recycling initiatives resulting in a projected 65% decrease of plastic waste going into energy recovery.

The UK could eliminate reliance on low-quality exports of plastic waste in the next 10 years and could more than halve the amount of plastic waste being exported.

The BPF report says that plastic waste ending up in landfill sites could reduce to only 1%, representing a 94% reduction. The UK could recycle up to 65% of all plastic and 75% of plastic packaging by 2030.

In addition to investment in UK recycling systems, the report calls for consistent plastic waste collection schemes across all local authorities, kerbside collection of plastic film, increases in the use of recycled material in new products, and better communication to the public about what can be recycled. In total, 16 key changes are required.

The document also makes it clear that to significantly increase domestic recycling capacity, recycling rates need to rise for a range of plastic products – not just packaging. The construction, automotive, electrical and electronics, household, sports and leisure, and agriculture sectors represent a higher amount of plastic use in total than packaging and more needs to be collected and recycled.

The report calls for specific product recycling schemes to be set up for products not currently collected at kerbside.

Data within the report reveals that the amount of overall plastic being recycled has grown by 150% since 2006. Over the same period, plastic going into landfill has reduced by 70%, so the UK has a track record of progress to build upon.

Local issues
The varied approach of local authorities on what can and cannot be recycled from their kerbside collections should also be noted. Somehow there has to be an agreed approach to create consistent streams of different plastic types.

Dr Adam Read, Director of External Affairs at SUEZ Recycling and Recovery UK, says, 'If we are to achieve the desired step-change in our recycling rate and also meet increasingly stringent quality requirements for both our overseas and home-based reprocessors of our sorted plastics streams, then the UK needs to rise to the dual challenge 
of expanding the range of plastics we commonly capture and recycle, and improving the quality of plastic recyclate we handle and pass on across the board. 

'Getting EPR and its associated new funding flows from the brands will be key to enabling new services and processing sites to be developed, so we hope the new team at the UK Department for Environment, Food & Rural Affairs move fast to make EPR and consistent collections a priority in the coming months.

'Expanding our domestic reprocessing capacity for plastics presents an opportunity to support both green growth and the creation of a more circular UK economy, with skilled job opportunities, where we reduce our reliance on primary resources by producing quality secondary materials that are easily integrated into manufacturing systems.'

Price watch
Read continues, 'Looking ahead, we need to keep a watching brief on the price of recycled polymers as energy and labour costs rise, both here in the UK and globally, and government may need to look again at introducing a plastic tax escalator above the current Plastic Packaging Tax to ensure recycled polymers remain competitive and ideally attractive to business as we look to meet higher targets and change our supply chains forever.

And as for DRS and its role in delivering improved plastic packaging collection and reprocessing, this is not a priority right now. More on-the-go bins and communication campaigns should help address the litter issue, while EPR and consistent collection reforms drive up capture rates and quality.

'We will continue to work with our municipal customers to ensure as much of the target materials are captured to the right quality to enable them to be recycled, while investing in alternative end-markets as the opportunities arise.'

In development
Holistic resource management 
To face the challenges of mismanaged waste, TOMRA, in partnership with Eunomia, has developed a holistic approach to waste management that combines three practices – DRS, separate collections and mixed waste sorting (MWS). They call this combination ‘Holistic Resource Systems’.

The three collection methods are:

  1. DRS as a collection method for bottle-to-bottle clean loop recycling by processing food-grade PET bottles. Once collected, the PET bottles are pre-sorted at a recycling plant to remove any foreign materials, shredded into flakes and decontaminated in a hot washing treatment. Thereafter, they go through the processes already covered to produce transparent and colour-specific rPET products.
  2. Separate collections of organic, textile, e-waste, paper and glass (also known as source-separated recycling or dual-stream recycling). This concept relies on consumers to separate their waste by material type and discard it in a dedicated bin for recycling.
  3. Mixed waste sorting (MWS) is for materials that are not effectively captured by DRS or separate collections and can be recovered through mixed waste sorting. Municipal waste contains valuable secondary raw materials.

If processed with advanced mechanical recycling, virgin-like recycled plastic can be generated and kept in a closed loop minimising reliance on raw materials.

Part of this approach/process is the implementation of state-of-the-art sorting technology, based on near-infrared technology. High performing, intelligent sorting machines accurately identify materials and sort them as per requirements. The purer the sorted fractions, the higher the quality of the recyclate. With these high-quality recyclates, brand owners have the necessary material at hand to meet the EU’s recycled content targets.

Mixed waste sorting can capture more than double the amount of plastic packaging for recycling. Moreover, by collecting and sorting mixed waste materials before they are burnt or tossed into landfills, we can avoid up to 730Mt of CO2 emissions by 2030, reports TOMRA.

Polypropylene (PP) is a major plastic used in food packaging and other containers due to strength at thin gauge and ability to withstand hot liquids. Nextek is developing the infrastructure and systems for recycling PP to food-grade status called NextLoopp (see Materials World, July/August 2022 for an article on this technology).

In a later development, Dr Jon Mitchell, Projects Manager at Nextek, describes COtooCLEAN, which 'aims to turn LDPE, HDPE, PP films into food-grade recycled plastics so they can be re-used in films'. They are projecting 10 operating plants each processing 6ktpa, approximately 60ktpa of output, that would provide almost 20% recycled content for the UK within the next five years.

Mitchell says, 'This approach could help divert these materials into high-value, circular, film-to-film applications, and save 78ktpa CO2e (based on life cycle assessment estimates). As such, COtooCLEAN is poised to contribute three of the Plastic Pact targets, which are 100% of plastics packaging to be reusable, recyclable or compostable; 70% of plastics packaging effectively recycled or composted; and 30% average recycled content across all plastic packaging.'

On Pack Recycling Label 
The On Pack Recycling Label (OPRL) scheme aims to deliver a simple, consistent and UK-wide recycling message on retailer and brand packaging – whatever the sector – to help consumers reuse and recycle more material correctly, more often. According to this independent organisation, its simple consistent message is now recognised by more than three out of four consumers, with over 700 members now using it.

Mixed flexible plastic waste trials
SUEZ brought together key players across the value chain to produce their 2021 report on flexible plastic recycling (films, wrappers etc). This highlighted that 'while achievable, significant investment is needed in collection, sorting and reprocessing infrastructure if they are to mainstream effective recycling of flexible plastics.

'Although government continues to suggest that flexibles will be a priority material for collection, less has been said about avoiding cross-contamination of materials and ensuring end-markets are live. These are areas being worked on with a number of large brands and local authorities right now through the FlexCollect project.'

A separate initiative led by the major supermarkets, Tesco and Sainsbury’s, is now at the large-scale trial stage, whereby shoppers can return all their soft plastic packaging to recycling points at every large UK store. Tesco reports that the material will be processed into refuse sacks after ensuring that the liners have “suitable strength”, with the resultant recycled plastic pellet being blended with recovered agricultural films, such as baling wrap.

A start-up company, Polytag, seeks to offer easy access to information about packaging lifecycles in the circular economy, and tools to optimise and incentivise recycling by collaboratively working with all stakeholders throughout the circular economy, including packaging producers, retailers, brands, local authorities, recyclers and the government.

Empowering plastic
With the current emphasis on net-zero and the circular economy, mechanical plastic recycling must surely develop into a major contributor to those targets. This can be achieved while ensuring plastic use is maintained and develops further in its significant key roles of bringing lightweighting with strength for packaging, medical, automotive and construction. Now if littering could be reduced to increase the waste stream for recycling, the opportunities could be plentiful.

Sorting solutions

TOMRA Recycling Sorting has sought to optimise its waste management process. It supplies sorting units to recover recyclables from waste in the following steps:
  • Waste is collected and transported to a sorting or recycling facility and fed into plant with mechanical pre-sorting steps to remove larger contaminants.
  • Sensor-based sorting separates materials by type and/or colour. The technology instantly identifies the different types of recyclable materials and separates them from residual waste, with high-throughput sorting machines using compressed air to eject the materials for recycling.
  • Plastic waste such as light-blue PET is shredded into flakes and washed to remove contaminants. To produce the highest quality recyclates, the plastic flakes undergo hot washing and additional processing steps. TOMRA flake-sorting machines can process up to 6t of plastic flakes per hour and sort them by polymer type and colour with the clean flakes being sent for extrusion. 
  • This granulate can then either be added at a specific content together with fresh virgin material or used at 100% to make plastic products.


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Stuart Patrick FIMMM