Recent pioneering research has opened up exciting potential opportunities for the recycling of plastic-based flexible packaging. Used across numerous applications and markets, the format touches many aspects of our lives.
In the UK, 414,000 tonnes a year of flexible packaging is placed on the market. Such packaging – including plastic bags, confectionery wrappers, frozen food bags and pet food pouches – makes up 27% of consumer plastic packaging in the UK, yet much of it ends up in landfills or energy recovery. There are several reasons for this, mainly the lack of adequate collection, sorting and recycling infrastructure.
It is a complex and growing waste stream that, until now, has been difficult to recycle. Yet recovering and recycling it offers tremendous opportunities to preserve valuable resour-ces and reduce the amount being landfilled.
In 2011, several WRAP-funded trials demonstrated success with reprocessing waste polyethylene (PE) carrier bags into items such as refuse sacks, already a common practice in some European countries. As well as highlighting the need for more recycling of films and flexible packaging, this early work also showed the potential for resource recovery.
Crucially, there was a need for better understanding of the type of flexible packaging placed on the market and arising in the post-consumer waste stream. This was a key aim of the collaborative Reflex project, a consortium of key players from across the supply chain – from polymer production, packaging manufacturers, global brand owners, to waste management and recycling companies. As project leader, Axion Consulting worked with partners Amcor, Dow Chemical Company, Interflex Group, Nestlé UK, Suez, Tomra Sorting and Unilever.
Launched in October 2014, the project was co-funded by Innovate UK, a Government business support agency, and its oversight provided a valuable focus and structure to the studies. The overall aim of Reflex was to understand and address the technical barriers to mechanical recycling of flexible packaging in the post-consumer waste stream, creating a circular economy for these materials.
Compositional analysis on samples of current packaging in the consumer waste stream generated valuable data that was previously unknown in the UK. It showed that around 40% is PE, 35% is polypropylene (PP) and 20% are non-polyolefin laminates.
Around 80% of flexible packaging classified as polyolefin material is a positive finding, pointing to a larger proportion of potentially recyclable materials than previously thought. The data would aid work on redesigning packaging structures, provide information for evaluating sorting and processing technologies and useful input to identifying end market applications, although applicable only to the UK.
Several practical trials confirmed that it is technically possible to sort, wash and extrude post-consumer flexible packaging for mechanical recycling. Near-infrared (NIR) technology can identify PP, PE or mixed polyolefin streams along with multi-material laminates. NIR is considered sufficient for current needs in terms of producing a high-quality recyclate.
Packaging redesign to improve recyclability at end of life, taking into account a lifecycle assessment, was a key part of the project. Trials were undertaken at both small and production scale to manufacture new packaging structures. Potential modifications included moving to an all-PE or all-polyolefin structure for non- or low-barrier packaging and the replacement of non-polyolefin polymers in the structure.
Recyclability trials focused on overcoming a lack of prior knowledge on what structures could be recycled into high-quality recyclate. Overall, more than 50 flexible packaging structures and blends were tested using post-industrial and virgin materials, including samples provided by the converters and brand owners in the consortium.
Tests on reprocessing PE/PP laminates produced recyclates suitable for injection moulding applications. This key finding from Reflex suggests these polymers could be reprocessed together, making recycling the entire waste stream much simpler. As well as leading to greater yields, it would allow manufacturers to use PE/PP laminates that are suitable for mechanical recycling at end of life.
Other challenges explored in the research assessed the recyclability of coatings and aluminium foil. Although some coatings discoloured the recyclate, they did not reduce its quality. Foil significantly reduced the physical properties of recycled polymers. But it is possible for flexible packaging that contains aluminium foil to be recycled in the aluminium recycling stream and not in the plastic stream.
Ink removal remains a barrier. While the project demonstrated that it is technically feasible to remove inks from some types of flexible packaging, it is not economically viable at the moment to remove ink during the recycling processing for post-consumer household films. Further research would be worthwhile as the sorting and recycling infrastructure becomes established during the next five to 10 years.
Allied to this, research into a marking technology examined digital ‘watermarking’ for recyclable packaging. Invisible to the human eye so as not to disrupt branding, the mark’s unique code printed on packaging could be detected by sorting equipment and the item separated for recycling. Although promising, the technique needs further development before it could be used by the industry.
A key development under Reflex was the foundation of guidelines which could be used by packaging designers and brand owners to make informed decisions on material choice with regards to recyclability. The guidelines are based on the evidence obtained from the practical recyclability trials rather than the limited existing infrastructure. They consider all aspects of the packaging, including polymers, coatings, foils and inks, but will be further developed before being released.
The completion of the Reflex project in autumn 2016 created a knowledge base and collaborative network on which future projects can be built. Results and insights from successful trials have also increased significantly the understanding of flexible packaging recycling in the UK.
The project’s vision is that, by 2025, there will be an established collection, sorting and reprocessing infrastructure/economy for post-consumer flexible packaging across Europe. This would be based on end-of-life technologies and processes to achieve the best economic, technical and environmental outcome.
Analysis shows this would be viable in the UK, but achieving the vision would need appropriate infrastructure and around £100m of capital investment, according to the high-level estimates carried out as part of Reflex (see box). This includes two purpose-built reprocessing plants alongside modifications to existing sorting facilities to extract flexible packaging from feedstock streams. It would also require additional UK local authorities to offer kerbside collection of film within dry mixed recyclables.
Additional funding may also be required to support councils in establishing collections as well as activities such as communication campaigns to ensure householders participate and dispose of their packaging correctly.
The business case also highlights certainty in feedback and offtake markets so that recycling plants can be financed and constructed, as well as understanding the lifecycle of the proposed value chain.
So what happens next? The work started by Reflex will continue under a merger with a separate European project. Called Ceflex, this new project will continue to address the end-of-life barriers before implementing an optimised circular economy solution. It will also explore opportunities for setting up flexible packaging collection, sorting, recovery and recycling infrastructure across Europe.
Reflex is a great example of a research project where supply chain partners worked together to achieve what no single one could have done alone.
The business case for collecting, sorting and recycling post-consumer flexible packaging in the UK will require:
- A further 75 local authorities to adopting kerbside collection of flexible packaging
- At least 50% participation rate from the householder in each local authority
- A greater portion of flexible packaging suitable for mechanical recycling by integrating recyclability into the packaging design process
- Sorting and processing facilities to make the necessary investments in new equipment required to extract flexible packaging
- Certainty in feedback and offtake markets
- Lobbying for policy infrastructure to be in place
Richard McKinlay is head of engineering and research at Axion Consulting