A successful partnership among three research institutions has resulted in a roadmap for an economically viable process to recycle plastics using enzymes.

Source: PHYS ORG

The team, composed of researchers from the National Renewable Energy Laboratory (NREL), the University of Massachusetts Lowell, and the University of Portsmouth in England, previously worked together on enhancing PETase enzymes capable of breaking down polyethylene terephthalate (PET). Given its low production cost and excellent material properties, PET is widely used in single-use packaging, soda bottles, and textiles.

Key Findings of the Study

The recent study, published in Nature Chemical Engineering, combines previous fundamental research with advanced chemical engineering, process development, and techno-economic analysis to establish the framework for enzyme-based PET recycling at an industrial scale.

Current recycling methods for PET often struggle with typical low-quality plastic waste.

Enzymes present a promising solution, as they can selectively decompose PET, even from contaminated and colored plastic waste streams.

Process Improvements

The researchers' innovative design emphasizes enhancements at each phase of the process, including:

These monomers can be transformed into new plastic or upcycled into higher-value materials, conserving energy and resources.

Despite the advantages of enzymatic recycling for complex plastic waste streams, the field has encountered multiple challenges for realistic implementation. Here we have taken a multidisciplinary approach that incorporates multiple innovations to realize an economically viable and scalable process.

^{Gregg Beckham, a senior research fellow at NREL and co-lead of the study}

The viability of this process hinges on reducing energy and cost requirements, thereby resulting in a more affordable product. The team accomplished this through innovative changes in reaction conditions and separation technologies.

Economic Viability

The modeled cost of the resulting enzyme-recycled PET is now lower than that of U.S. domestic virgin PET ($1.51/kg compared to $1.87/kg), making it an appealing option for industry investment and scalability.

We see a significant opportunity to design, test, and optimize new recycling technologies to efficiently valorize postconsumer plastics into feedstock for new materials.

^{Natasha Murphy, a biochemist at NREL and co-first author of the new paper}

According to a 2022 NREL study, 86% of plastics were landfilled in the United States in 2019—representing materials with sufficient embodied energy to meet 5% of the power needs of the U.S. transportation sector. With global plastic production expected to rise by 2 to 4 times current levels by 2050, recovering and valuing more post-consumer plastics presents a significant opportunity to reclaim that energy for domestic materials manufacturing.