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.

Industry Trends

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.

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.

Recent Activity

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:

  • 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.

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.