Enzymatic Depolymerization and Recycling: Using Enzymes to Convert Linear Waste Streams into Circular Supply Chains
In the coming years, enzymatic recycling will play a crucial role in solving the challenges of the fashion, apparel, and textile industries, as well as other industries using hard-to-recycle materials, that are in urgent need of diverse and innovative solutions to transform these traditionally linear waste streams into circular ones. This sector has seen a significant increase in deal activity and investment in recent months and years, which is indicative of the global need to address growing volumes of plastic waste and the increased demand for high quality recycled plastic polymers and resins.
The Growing Waste Crisis
Currently, of the estimated 350 million tonnes of plastic waste produced annually, around 150-200 million tonnes will end up accumulating in landfills or polluting the environment. This is expected to increase rapidly as plastic production is expected to grow by 70% to 600 million tonnes per year by 2050 with at least 20% of this expected to be PET. These staggering figures all call for an immediate solution for reducing plastic waste and as well as for improved recycling systems. This is especially the case as regulations on waste imports are requiring producers of plastic waste to search for domestic recycling solutions and extended producer responsibility laws require producers and manufacturers of packaging materials and waste to support collection and recycling.
Almost 500,000 tonnes of food-grade rPET (recycled PET) will be needed to meet the demand for voluntary and regulatory mandated commitments in the next decade. This will require up to three times as much as the 150,000 tonnes of bottle-grade rPET that was produced in 2017. Demand owners and product manufacturers will need to look for suppliers of high quality rPET or they will come up short on commitments.
To get a better sense of where we are today versus where we need to be, it is helpful to analyze some industry trends that are paving the way for new opportunities.
- Voluntary Commitments Are Driving Demand for Post-Consumer Recycled Content. Leaders from food and beverage, apparel and other industries are making voluntary commitments to incorporate a large volume of recycled plastics into their products. Clothing companies that use polyester and nylon made from PET will require large volumes of rPET to produce their products. Unlike apparel companies which can accept lower quality recycled plastics, food and beverage companies will require high quality food-grade post-consumer plastics. Some examples of corporate pledges to incorporate recycled content into packaging and products include Coca Cola’s pledge to use 50% recycled materials by 2030 and Adidas committing to use recycled plastics wherever possible by 2024.
- Regulations are Requiring Recycled Content. Extended producer responsibility laws place pressure on producers of plastic waste. Minimum content laws require a minimum percentage of recycled plastics to be incorporated into plastic products and textiles, increasing the demand for high quality recycled plastics and PET. Legislation in the European Union indicates they will mandate the inclusion of 25% recycled content in PET bottles by 2025 and 30% in all plastic bottles by 2030 under the Single-Use Plastics (SUP) Directive. Similarly, in California, manufacturers will be required to include an annual average of 15% of postconsumer resin (PCR) in beverage containers starting in 2022.
- Technologies are Still Early Stage. Although the technology for enzymatic recycling appears promising with its ability to infinitely recycle polymers, some larger corporate players looking to recycle large volumes of plastic waste quickly cite that enzymatic recycling will still require time to scale to a commercial level — time that some corporations do not have.
- Virgin Plastic is Still Cheap. Although demand for recycled content is growing, rPET and recycled polymers are still more expensive to produce than virgin plastics which some corporations may prefer to use especially in countries where recycled content for food contact has not been certified.
Enzymatic Depolymerization as a Solution
Enzymatic recycling technologies allow for mixed, low quality and contaminated plastics, in particular PET, to be recycled without becoming degraded as would occur through mechanical processes and in many thermal depolymerization processes. These biological processes usually work by placing plastic waste in a bioreactor with specific enzymes such as PETase and MHETase that bind specifically to the PET polymers and monomers to depolymerize the long PET polymer chains. Once the monomers and constituents are separated out, they can be used and repolymerized to create high quality plastics or other petrochemical products.
This process usually requires less energy and has the potential to extend the life of plastics and recycle the polymers multiple times while producing virgin-like quality recycled plastic outputs. However, in some cases heat might be needed as a pre-treatment step to prepare the mixed waste and plastic waste for the enzymatic reaction. This can negatively impact the life cycle assessment and overall emissions of the process depending on the sources of energy used. Currently the most common polymer that can be depolymerized in this way is PET, but companies and research groups are looking at potential pathways to understand the options of commercializing recycling solutions for PEF (polyethylene furanoate), PE, PU and other polymers.
The past year has seen a substantial increase in funding and partnerships in the enzymatic recycling and depolymerization space. Funding will often be used to strengthen relationships with partners interested in procuring recycled content, beginning development of pilot or commercial recycling facilities, and enhancing the digital and machine learning systems that support enzyme development.
Innovators of interest include:
- Carbios (France):
- Carbios recently joined the WhiteCycle Consortium in July 2022, a public-private European partnership to recycle plastic waste that will operate for four years with the goal of recycling more than 2 million tonnes of PET with a global budget of 9.6 million euros.
- Carbios signed critical agreements with On, Patagonia, Puma and Saloman to develop and gather data on fiber-to-fiber recycling models following their successful trial producing 100% enzymatic recycled white PET fiber from colored textile waste. The recycled content was also used to produce 100% recycled PET bottles that have passed food contact validation tests.
- Carbios plans on developing a manufacturing plant in partnership with Indorama Ventures to enzymatically recycle up to 50,000 tonnes of PET waste that will be operational by 2025.
- Samsara Eco (Australia):
- Following a $6 million raise earlier this year, Samsara Eco has been seeing substantive growth with a recent investment of $34.7 million in a Series A round with investors including Breakthrough Victoria, Temasek, Assembly Climate Capital, and others. Funding will be used to develop their commercial facility expected to begin operations in 2024 with the ability to enzymatically recycle 20,000 tonnes of plastic.
- Epoch Biodesign (United Kingdom):
- In June, Epoch Biodesign raised an $11 million seed round with participation from Lowercarbon Capital, BoxGroup, MCJ Collection, and others. Funding will be directed towards the development of their enzyme design platform, expansion of research and development facilities, and scale up of their technology to pilot the production of chemical products from the depolymerized waste plastics.
- Birch Biosciences (United States):
- Birch Biosciences earlier this year received a grant from the U.S. Department of Energy to support the development of their enzyme-enabled mixed plastic waste recycling process that targets PET plastics and other waste streams that are not addressed through mechanical recycling processes.
- Enzymity (Latvia):
- Enzymity is developing a platform approach to create, research and enhance enzyme variants that can be used to address PET plastics and others, including polyurethane and cellulose through their machine learning and computer-based trialing systems. Their company recently received a grant from DigiCirc for advancing to the final phase of the circular solutions accelerator.
- Protein Evolution (United States):
- Protein Evolution recently came out of stealth mode in October of this year with an announcement that it had raised over $20 million in initial funding from partners including the Collaborative Fund, New Climate Ventures, Eldridge, Nextrans, and Good Friends, to scale their proprietary enzymatic recycling process.
- Plasticentropy (Spain):
- Plasticentropy has identified enzymes that can degrade PE (Polyethylene), a polymer that comprises roughly 30% of all plastics produced and has strong carbon to carbon chains that are traditionally more difficult to breakdown enzymatically when compared to other polymers like PET. They are building upon research published earlier this quarter on the enzymes found in wax worm saliva that can oxidize and depolymerize PE in a few hours at room temperature and are raising their seed round currently to scale and develop their process.
Keep an Eye Out
As investors and corporations look towards enzymatic recycling and degradation solutions to address problematic waste streams, challenges related to waste collection and sorting will also have to be considered. Solution providers should ensure they have access to the necessary volumes of feedstock and are not potentially competing with mechanical recycling solutions that already have strong collection and recycling programs. This will become increasingly important, especially as regulations play a larger role in encouraging waste producers and packaging manufacturers to take responsibility of their plastic and textile waste.
Collection infrastructure is required. Feedstock for PET enzymatic recycling can come from lower quality PET plastics like those found in textiles, clamshells, colored bottles, and mixed waste that do not currently have closed loop end solutions. However, these waste streams are often not collected regularly as compared to clear, plastic PET bottles that already have strong collection and mechanical recycling systems in place.
However, there is still quite the potential for recyclers to generate substantial returns by converting low quality, colored, and contaminated plastics that would typically only have low quality downstream solutions, into high quality, clear and food-grade resins that are much more profitable.
Additionally, up and coming biopolymer solutions like PEF that closely resemble PET but are biobased, will require further research on how enzymatic recycling affects these polymers as innovative new resins and biopolymers gain popularity and are tested through new packaging formats.