Martyn Tickner, Chief Advisor of Circular Solutions at the Alliance to End Plastic Waste and Arun Rajamani, Managing Director and Partner of Boston Consulting Group (BCG), discuss how mechanical recycling is transforming mixed plastic waste into valuable products, supporting a circular economy, and overcoming key recycling challenges.
The Alliance to End Plastic Waste has recently launched its third Solution Model Playbook, “Capturing Value Through Basic Mechanical Recycling of Mixed Plastic Waste.” This innovative guide explores how mechanical recycling can convert plastic waste into valuable resources, supporting both environmental sustainability and economic growth.
Plastic waste is one of the most pressing environmental challenges today, with millions of tons ending up in landfills and oceans every year. While recycling offers a path toward sustainability, not all plastic waste is easy to process. Mechanical recycling – which involves sorting, cleaning, and reprocessing plastic into new materials – is a key solution.
This interview explores how mechanical recycling can help address these challenges. Alliance and BCG experts in plastic waste management discuss its role in building a circular economy, the technical and economic barriers that must be overcome, and how innovative recycling strategies are creating new opportunities for sustainability.
Mixed plastic waste is notoriously difficult to recycle economically. Can you explain the key challenges and what makes mechanical recycling a viable solution in addressing these issues?
Martyn: Where plastic articles are easily collected as a clean, segregated stream – for example, PET beverage bottles and post-commercial back-of-retail store bulk packaging – or easily sorted – for example, HDPE milk and fruit juice jugs – mechanical recycling to meet recycled content targets and achieve high value, plastic-to-plastic solutions is technically and economically attractive.
However, for mixed household waste, it is technically challenging and costly to sort plastic waste streams to achieve the required feedstock quality for recycling. Establishing the necessary collection systems and sorting infrastructure requires significant economic incentives such as mandated targets and Extended Producer Responsibility schemes, as well as building on years of experience in efficiently managing waste.
In the absence of mature systems, regulations and financial frameworks, basic mechanical recycling is an excellent way to kickstart a recycling economy. It is, therefore, optimal for countries at an early stage of waste-management maturity, enabling them to adopt solutions that capture value from waste, encourage entrepreneurial development and begin to establish the structures and financial capabilities that are required to progress to more advanced solutions.
Arun: Conventional closed-loop recycling — i.e. mechanical recycling into a product with similar properties to the original — requires a highly clean and single waste stream, such as single-polymer PET bottles or natural HDPE milk jugs. In contrast, mixed waste streams are often contaminated (with dirt, metal, paper, food, etc.), multilayered, and pigmented, making sorting into single polymer streams difficult and challenging to recycle.
Mixed streams can undergo chemical recycling, but the technology has not yet been widely scaled. Another alternative is energy recovery from the mixed waste stream. However, its environmental benefits are lower than those of recycling, and it doesn’t support a circular economy.
This is where open-loop (or basic) mechanical recycling comes in. It downcycles mixed waste streams into second-life products, such as outdoor benches and wall cladding panels, making it a viable solution that positively impacts the overall lifecycle assessment compared to incineration or landfill disposal.
Can you share examples of how recycled mixed plastic waste is being transformed into valuable products like furniture and eco-aggregates and how this supports a circular economy?
Martyn: Examples of Alliance projects featured in the Playbook include:
CDRC Global – An initiative to capture value from the world’s mixed plastic waste by converting it into RESIN8™—an eco-aggregate manufactured through basic mechanical recycling which can help improve the strength and thermal properties of concrete, reducing the need for carbon-intensive and ecologically damaging excavation and transportation of traditional concrete aggregate including sand and gravel.
ASASE Foundation – Supports local (predominantly female) entrepreneurs from vulnerable communities to collect and process plastic waste. This involves collecting both low- and high-density polyethene plastic waste to be washed and ground at ‘Cash It!’ plants in several locations in Accra. The regrind is fed into an extruder to produce pellets, which can be transformed into household or building materials.
Other Alliance projects see materials being sold into roofing tile applications, paving slabs and plastic lumber. The use of mixed recycled plastics in garden furniture, decking, paint buckets, railway sleepers, paving slabs, building bricks and blocks, and roofing tiles is quite widely established, including in economies at a higher level of waste management maturity.
The core focus of our Playbook, however, is that such solutions are economically viable without the need for extensive financial incentives and, therefore, very suitable for entrepreneurial development in countries with early-stage waste management systems. This also sets out a path for capturing value from plastic waste and establishing a circular economy in which materials are kept in circulation for as long as possible.
In countries like the UK with advanced waste management systems, how do your solutions address residual plastic waste streams that still persist?
Martyn: Basic recycling solutions such as mechanical recycling are an excellent way to kickstart recycling economies in countries with nascent or early-stage waste management systems.
However, even in developed nations that possess more advanced waste management and recycling capabilities, the costs and complexity of sorting, transporting, and processing some of the residual waste streams are difficult to justify economically. Basic recycling solutions can then play a role in addressing the challenges posed by mixed plastic waste streams.
How does recycling fit into the broader framework of a circular economy for plastics, and what barriers still need to be overcome globally to achieve this vision?
Martyn: Alongside reduce and reuse strategies, recycling is an integral piece of the puzzle to address plastic waste in the environment. A circular economy for plastics is not possible without recycling. Increasing recycling rates will make a key contribution to reducing and eventually eliminating plastic waste in many countries, especially emerging and developing economies.
In terms of key barriers, many emerging and developing economies still lack basic waste collection infrastructure, which allows plastic waste to leak into the environment rather than being valorised and kept in circulation.
Insufficient funding for waste management systems lies at the heart of the plastic waste challenge, with an estimated US $2.1tn needed by 2040 to eliminate plastic leakage into the environment. Countries across the globe are currently hindered by chronic underinvestment in waste management infrastructure, particularly collection infrastructure, which is the least profitable and, therefore, the most underfunded aspect of waste management.
Additionally, the transition from a linear fossil-based economy to a circular economy requires economic incentives to drive adoption. The most effective incentives are those that reduce the cost of capital, either through blended (development and philanthropic funding + private sector) finance, through mechanisms that improve the certainty of revenue, for example, Extended Producer Responsibility schemes and mandated recycling targets, or through cost subsidies such as land rents, utility costs, and labour costs.
Arun: Globally, plastic waste management largely follows a linear economy model, relying on incineration and landfill disposal, with only 10-15% of plastic waste recycled, varying widely across markets. Enhancing recycling and reuse is key to promoting a circular economy, where all stakeholders —including producers, distributors, and consumers—work toward better waste management and reduction.
However, economic, technical, environmental, and regulatory barriers hinder progress. For instance, upstream processes like collection, sorting, and cleaning are costly, making mechanical recycling of mixed streams challenging.
Major challenges include:
Insufficient waste collection infrastructure leaves much of the global population without proper disposal options.
High contamination of post-consumer waste makes recycling inefficient and costly.
Low demand for recycled plastics leads to economic viability issues.
Uncontrolled dumping and burning of municipal waste exacerbate environmental pollution.
Addressing these barriers through policy interventions, infrastructure investment, and industry collaboration is essential to accelerating the transition toward a sustainable circular plastics economy.
Public-private partnerships (PPPs) are highlighted as critical to recycling success. How do these collaborations ensure a reliable feedstock supply and drive economic feasibility?
Martyn: PPPs are very relevant to collection and recycling, where most collection schemes are a public sector responsibility in providing waste management as a community service but contracted out to private companies to invest in the required infrastructure and manage the operations, selling the output materials.
Several Alliance projects involve a private sector entity establishing a collection system and sorting infrastructure, which will be handed over upon completion to the municipality for operation, for example, the ParikraM project with Recity in India.
PPPs as well as other strategic partnerships, play a vital role in ensuring the success of certain recycling projects. For example, partnering with end-users in industry for manufacturing of saleable products enhances the viability of the operation, ensuring revenue can be generated downstream.
Establishing strategic and public-private partnerships can help catalyse a connected value chain to unlock wider opportunities. These partnerships connect upstream feedstock support through effective collection systems, which ultimately supply and link downstream recycling activities.
PPPs can also be considered with respect to financing, for example, in enabling the sharing of price and volume risks to ensure sustainable margins for the recycler. In addition, blended finance can help to attract the required financing for a project. For example, the Alliance seeks to derisk the investment in a project by other debt providers and equity contributors through grants and concessional loans.
What are the most important lessons from your new Playbook, and how do you envision governments and businesses replicating and scaling these solutions in diverse economic contexts?
Martyn: Basic recycling is a way to kickstart a recycling economy – it doesn’t need complex supportive legislations and economic interventions – and can be driven by local entrepreneurs ahead of the strong government support that is required to accelerate the transition to circular solutions.
In order to maximise impact, adequate collection infrastructure is essential for a consistent supply of feed, and innovative solutions should be used to enhance lifecycle impact and resource utilisation. In addition, multiple revenue streams are needed to maintain the economic viability of business and educational campaigns are crucial when building a skilled workforce to foster buy-in.
Arun: To scale these solutions across diverse economic contexts, governments and businesses could:
1) Foster supportive partnerships: Collaborate with industry and local municipalities for steady feedstock supply and end-product conversion and sales channels
2) Ensure context-appropriate technology: Utilise sorting and recycling equipment that aligns with local conditions, waste compositions, and buyer requirements
3) Implement financial interventions: Strengthen market mechanisms through EPR regulations and plastic credit systems to support a sustainable recycling business model
4) Develop certifications/standards: Ensure fit-for-purpose products meet industry standards, as this can build a sustainable customer base and enable scalability
5) Test, iterate and scale: launch pilots, monitor progress, and adjust strategies to the local context before full-scale implementation.
By embracing these strategies, governments and businesses can boost recycling rates, stimulate economic growth, and contribute to environmental sustainability.
What’s next for the Alliance and BCG, and how do you plan to expand on the success of this Playbook to drive further innovation in waste management?
Martyn: We will continue to share the learnings and experiences gained through the projects we fund. Our objective is to share our knowledge so that like-minded organisations can build on what we have done.
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