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The future circularity of plastics: the necessary coexistence of chemical and mechanical recycling

Promeco® has been active in the green economy since 1996, producing a wide range of waste recycling solutions.

To enable the achievement of the goals Europe has set for itself, the transformation to climate neutrality and the creation of a circular economy to curb waste and, above all, drastically reduce the use of fossil raw materials is essential. In the light of this approach, the production, use and treatment of post-consumer and post-industrial plastics must be reviewed. Categorically ruling out the plastic-free trend, having proven that it is impossible to give up plastics in their applications in the health, food and technical fields, there are two known solutions on the market today to increase the recycling of plastics: mechanical recycling and chemical recycling, both of which are contemplated in Promeco® plant offerings.

It is often discussed that chemical recycling is taking market share away from mechanical recycling, but this is completely the wrong approach. While there is no question of the need to increase mechanical recycling, it must be clear that chemical recycling takes over whenever mechanical recycling shows its limitations. So one does not exclude the other; if anything, they can coexist to be one in support of the other.

Mechanical recycling, as Corepla well explains, consists of a sequence of operations: shredding, washing and removal of unwanted fractions, to which is added the densification and extrusion stage and is completed with the subsequent production of flakes, densified or granules. In this way, plastic waste is transformed into Secondary Raw Material, ready to be fed as a semi-finished product into new production processes. But mechanical recycling cannot go on indefinitely: its overuse results in the alteration of the material with the consequent depletion of polymer chains. In fact, this is referred to as downcycling, as the recycled material is of lower quality and functionality than the original material. In addition, mechanical recycling has obvious limitations in the valorization of mixed, heterogeneous, and poly-bonded waste.

Chemical recycling, for its part, makes it possible to recycle plastic waste for which there are no alternative solutions today and is the optimal solution for all those mixed waste streams that are difficult to valorize with mechanical recycling. This is a theoretically infinite virtuous process of plastic recycling, which makes it possible to produce from volumes of plastics significantly larger than those destined for mechanical recycling, new virgin polymers suitable for every application and with characteristics identical to those coming from fossil sources. With chemical recycling, such as Promeco® Chemical Recycling, plastic waste is reconverted into chemical compounds that form the basis for the production of fuels, raw materials of interest to the chemical and petrochemical industries, as well as into the raw materials themselves from which plastics can be produced again, reducing the need for additional natural resources and facilitating their regeneration. And it is in this logic that chemical recycling stands as complementary to mechanical recycling since it allows the valorization of heterogeneous waste, complex mixtures, contaminated allowing the obtaining of a material with quality comparable to virgin material. If we want plastics, from waste, to become a resource in the imminent transition to a circular economic model, chemical recycling of waste must also be implemented on a large scale, taking care to maintain a logic of sustainability and thus favoring those virtuous processes that can do without the typical steps of mechanical recycling, such as washing. A recent paper (Onur D. et al., PECS (84) 2021) conducted in collaboration between the Politecnico di Milano (CRECK Modeling Lab) and the University of Ghent analyzed the status of the chemical-physical processes underlying the chemical recycling of plastics highlighting "how a wide and widespread use of chemical recycling can result in the reduction of greenhouse gas emissions exceeding 100 million tons of CO2 equivalent, primarily due to a more efficient use of natural resources." While the importance of both plastic recycling processes, mechanical and chemical, is thus proven to enable the achievement of the goals that Europe has set for itself, it is also desirable that products obtained from chemical recycling be recognized as recycled under the same regulatory criteria as mechanical recycling so that there is a valid classification for both processes.

Promeco®, an Italian company operating internationally, is able to offer high-tech solutions for both mechanical and chemical recycling of plastics. The quality of the proposed solutions is measured in terms of solidity, high technological value, and maximum functionality. The ability to challenge and interact at all levels has allowed and still allows Promeco® to be highly competitive and the ideal partner.


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