The Brief: How viable is biorecycling for plastics?

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Introduction:

Over the last few years, the possibility of biorecycling plastics (particularly PET) has emerged. In this Brief we detail some of the current research and developments, look at the challenges involved (such as whether it can be implemented at scale), and ask if its place in recycling could be seen as an addition or an alternative to current methods.

Key takeaways:

• Current research and developments include Carbios’ plans to build a manufacturing plant for its biorecycling technology in France; Epoch Biodesign’s “tuneable” enzymes that can be programmed to transform plastics into different chemicals, with molecules from the biorecycling process used in applications including detergents, textiles, paint and coatings; and the EU funded Enzycle research project focused on discovering new enzymatic processes to treat and recycle plastic fractions.
• Some of the main challenges in biorecycling plastics are the environmental consequences when degrading plastics and the difficultly of competing with existing “scalable, cost-effective technologies” to recycle PET such as metal-catalysed depolymerisations (Ramani Narayan, Michigan State University).
• Is biorecycling plastics a scalable solution? Important considerations here are implementation costs, limited applicability (as enzymes are currently limited to degrading certain of plastics) and knowledge gaps to address unintended consequences. It is currently unclear if biorecycling could be implemented on a large scale at industrial level, as infrastructure is still being developed and research is ongoing.

Conclusion:

Whilst biorecycling does hold promise, as research and development is still ongoing, it is difficult to say whether it will become a scalable solution in future. However, developments such as Epoch Biodesign’s “tuneable” enzyme solutions and future plans such as Enzycle’s experiments indicate this is an area to keep a close eye on.

Over the last few years, the possibility of biorecycling plastics (particularly PET) has emerged. In this process, enzymes are used to break down PET into monomers, which are then purified and can be reused to produce new PET plastic bottles and packaging.

In this edition of The Brief, we will outline the current research and developments happening around the biorecycling of plastics, look at the challenges involved (such as whether it can be implemented at scale), and ask if its place in recycling could be seen as an addition or an alternative to current methods.

Current research and developments in biorecycling

French biochemistry company Carbios is aiming to utilise biorecycling for PET, claiming to have developed the “first biological process” which breaks down all kinds of PET plastic waste into original components, which are then reused to produce virgin plastic products.

The company’s chief science officer Professor Alain Marty described this process in more detail in the Nestlé Waters podcast We Are Talking: BIORECYCLING, adding that the solution is designed to be an industrial solution that keeps and changes existing PET facilities, and requires the addition of a depolymerisation unit.

Back in 2019, the company announced its successful development of the first PET bottles made from 100% Purified Terephthalic Acid (rPTA), through enzymatic biorecycling. In June 2021 it announced a non-commercial pilot with cosmetics brand Biotherm to create a bottle for the ‘Waterlover Sun Milk’ product, allegedly made from “100% biorecycled PET plastic”.

In September 2021, Carbios launched its industrial demonstration plant operating with enzymatic recycling technology; and in collaboration with Indorama Ventures, Carbios plans to build a manufacturing plant for its biorecycling technology in France, aiming to be operational by 2025.

Another company utilising biorecycling is Epoch Biodesign, with a goal of transforming waste into everyday chemicals. It claims to have designed “tuneable” enzymes that can be programmed to transform a variety of plastics into different chemicals, with molecules from the biorecycling process used in applications including detergents, textiles, paint and coatings.

In terms of research, the European Union funded RECOVER project aims to “solve the accumulation of non-recyclable agricultural and packaging plastics and micro-plastics pollution through biotech solutions”, including a combination of microorganisms, novel enzymes and earthworms. It is hoped that these can be used to degrade plastics and transform them into value-added products. Started in June 2020, the project will run for 4 years.

Another objective is developing processes for the biotransformation of conventional plastics into bio-fertilisers and biodegradable plastics for agricultural and food packaging applications. Partners of the project include the University of Almería in Spain, Nutrinsect SRL from Italy, Organic Waste Systems from Belgium and ASA Special Enzymes GmBH from Germany.

A second EU funded research project is Enzycle, which looks for new enzymatic processes to treat and recycle plastic fractions that could not be recycled previously. Enzymes with the potential to degrade non-recycled plastic fractions will be selected, produced in a bioreactor and tested for suitability in industrial applications.

Target materials for the research include multilayer packaging, post-consumer PET trays, clamshell containers and microplastics in waste water. Apparently, the expected products and processes aim to be applicable in areas such as packaging, transport and textiles.

The project plans to reduce the cost of plastic recycling, create a new bio-based value chain, new markets and decrease non-biodegradable polymers sent to disposal or discharged to the environment. Partners include Greiner Packaging and the University of Leipzig.

The challenges: development, scaling and implementation

As much research is still ongoing into biorecycling, there are several challenges present at the development stage. Back in 2018, an article by Chemical and Engineering News highlighted several of these.

Speaking to the magazine, Ramani Narayan, specialist in biodegradable polymer systems at Michigan State University raised the issue of environmental consequences when degrading plastics, saying: “without demonstrating complete degradation, whether to CO2 or recovered monomers, there’s a chance that leftover plastic fragments could wreak havoc on the environment.”

He added that there are existing “mature, scalable, cost-effective technologies” to recycle PET such as metal-catalysed depolymerisations and it’s “tough to compete with the low price of virgin monomers”.

Till Opatz of Johannes Gutenberg University Mainz pointed out the need for the media to be cautious when reporting on biorecycling. “If you tell the public that this problem has been solved when it hasn’t, people will be waiting for practical solutions, and they’ll be annoyed if in 10 years’ time there’s still polyethylene debris lying around or floating in the oceans.”

Is biorecycling a scalable solution?

An article by the U.S Government Accountability Office last November highlighted several challenges: implementation costs, as recycling plastics is “generally more expensive” than creating new plastics and there may be high start-up costs to develop biorecycling facilities; limited applicability, as the enzymes researchers have identified are currently limited to degrading certain types of plastic; and knowledge gaps, as research is needed to address the unintended consequences of biorecycling.

It also mentioned the current methods of mechanical and chemical recycling and how biorecycling could be viewed in relation to them, stating that “industry is considering advanced technologies such as biorecycling and chemical recycling as complements or alternatives to mechanical recycling”.

A Science Direct report by Lilia S. Lens-Pechakova in June 2021 stated that “the necessity to find an effective solution that matches the low productive cost of PET and a sustainable treatment of its wastes is indisputable”. However, when discussing PET hydrolases [a group of enzymes that exhibit the ability to hydrolyse PET because of their water solubility] it says that the recycling of PET on a large industrial scale could be made possible “only if the enzymes are engineered to be more active, specific and stable”.

The report added that when “potent novel PET hydrolases” are identified and successfully engineered, the flow of plastics from raw material to waste disposal could be closed through reuse of the depolymerisation products.

Currently, it is unclear whether biorecycling could be implemented on a large scale at industrial level, as infrastructure is still being developed and research is ongoing. Whilst developments such as Carbios’ pilot with Biotherm indicates it is achievable at small scale, challenges such as implementation costs and limited applicability need to be considered.

However, there are clearly biorecycling efforts being made which may have more far-reaching impact in future: Epoch Biodesign raised a $11 million seed round last year in order to expand its design platform, construct new research and development facilities and scale up its first solution, and Carbios’ manufacturing plant is scheduled to be operational in 2025.

Ultimately, whilst biorecycling does hold promise, research and development is still ongoing, and at present it is difficult to confirm whether it will become a fully scalable solution in the future. On that note, the developments already made such as Epoch Biodesign’s “tuneable” enzyme solutions and future plans such as Enzycle’s experiments on enzymes which could potentially degrade non-recycled plastic fractions indicate this is an area to keep a close eye on.