Biological Recycling Technology: Paving the Innovative Path for a Sustainable PET Circular Economy

Market Applications of PET and Its Recycling

Globally, PET bottles are among the most significant applications of PET materials, with a production volume of approximately 60 million tons in 2022. The textile industry is another notable application, producing around 5 million tons of PET fibers in the same year.

Despite widespread usage, global recycling rates for PET remain low. While some regions, particularly parts of Europe, have achieved recycling rates exceeding 60% for PET bottles through policy incentives and increased consumer awareness, the global recycling rate was only about 29% in 2020. The textile industry faces an even greater challenge, with PET recycling rates estimated at under 20%. This substantial volume of unrecycled PET exerts considerable environmental pressure, as it can persist in nature for decades, adversely impacting ecosystems and human health.

Biological Recycling Technology: A Sustainable Innovative Path for PET Upcycling

Numerous companies and research institutions are developing new technologies to enhance the efficiency and reusability of PET recycling. Biological recycling leverages microorganisms or enzymes to decompose PET waste into its constituent monomers, providing a sustainable alternative to traditional "downcycling" methods.

Comparison of Recycling Methods

Mechanical Recycling: This widely used technique cleans and pelletizes PET waste through physical processes. While efficient and cost-effective, it often diminishes material performance and cannot fully replace virgin PET. Additionally, it consumes water and energy, impacting the environment.

Chemical Recycling: This method breaks down PET into high-purity monomers through chemical reactions, offering high efficiency and adaptability for contaminated PET waste. However, it generally requires higher energy inputs, incurs greater costs, and may present environmental risks.

Biological Recycling: In contrast, biological recycling acts as an "upcycling" process, converting discarded PET into regenerated plastics that match the performance of virgin materials. While still in experimental stages, biological recycling holds significant potential to become a vital complement in PET recycling, promoting sustainable resource utilization.

The Genesis of Biological Recycling

Research into the biological recycling of PET has focused on specific bacteria and enzymes capable of degrading PET. A notable breakthrough occurred in 2016 with the discovery of *Ideonella sakaiensis*, a bacterium that survives using PET as its sole carbon source.

 This finding not only unveiled nature's degradation capabilities but also provided essential insights for developing new biological recycling technologies. Subsequent research has optimized the performance of PETase through genetic engineering, significantly enhancing its efficiency and speed in degrading PET.

Exploration and Commercialization of Biological Recycling

At the end of 2023, the International Union of Pure and Applied Chemistry (IUPAC) recognized "PET Biological Recycling Technology" as one of the "Top 10 Emerging Chemical Technologies of 2023." This initiative aims to identify technologies situated between laboratory research and commercialization that contribute to Sustainable Development Goals (SDGs).

Many domestic and international research institutions and companies have made significant breakthroughs in PET biological recycling, gradually advancing toward commercialization.

1. Biological Recycling from Waste Textiles to Regenerated Polyester Shirts

Yuantian Biotechnology (Tianjin) Co., Ltd. was established in October 2022 and specializes in the research and commercialization of enzymatic regeneration technology for discarded PET plastics. The company transforms waste textiles into high-value recycled monomers, such as purified terephthalic acid (PTA) and ethylene glycol (EG), successfully producing China's first enzymatically regenerated polyester shirt. This innovation is attributed to the company's development of directed-engineered enzyme proteins, enhancing regeneration efficiency, stability, and reusability while reducing production costs.

2. Achievements in Efficient Enzymatic Recycling of PET and Global Collaboration

CARBIOS, founded in 2011, specializes in plastic recycling and has made significant advancements in biological PET recycling by optimizing naturally occurring enzymes. The company has engineered a high-efficiency PET hydrolytic enzyme that demonstrates remarkable enzymatic efficiency, achieving up to 98% PET degradation in two hours during lab tests and 95% in commercial applications within 24 hours.

To further enhance its technology, CARBIOS is constructing the world’s first PET depolymerization plant in France, promoting plastic circularity and facilitating global technology applications. Collaborations with China's Zhink Group, Turkey's SASA, and the UK's FCC Environment aim to license its technology worldwide, driving innovations in PET recycling.

Wankai New Materials Co., Ltd., a subsidiary of Zhengkai Group, focuses on PET polyester materials and seeks to improve PET recycling technologies. The collaboration with Zhink Group and CARBIOS will enhance Wankai's product development and technological capabilities, driving production processes toward environmentally friendly practices and increasing recycling rates for discarded PET.

3. Utilizing Enzyme Technology for Infinite Plastic Recycling

Samsara Eco, in partnership with the Australian National University (ANU), has developed biotechnology that utilizes enzymes to break down plastics into their original structures. This breakthrough enhances recycling efficiency, with degradation and reuse rates significantly surpassing traditional methods. The new plastics produced meet high-quality standards, making them competitive in the market.

Samsara Eco plans to establish recycling facilities in Southeast Asia to process millions of tons of plastic waste, including textiles and packaging materials, with the goal of promoting "infinite recycling" by the end of 2026.

4. Combining AI and Biotechnology to Drive Plastic Waste Conversion

Recent innovations that merge artificial intelligence (AI) with biotechnology have led to significant breakthroughs in plastic waste conversion. The Biopure™ process by Protein Evolution exemplifies these advancements, transforming textiles and plastic waste into infinitely reusable resources.

Protein Evolution's technology, designed to create tens of millions of efficient enzymes, effectively degrades plastic waste, contributing to plastic circularity. The company collaborates with Basecamp Research to develop new enzymes capable of decomposing complex chemical chains such as polyurethane and nylon, which will greatly enhance recycling efficiency for various plastics and textiles.

Conclusion

With ongoing research into microorganisms and enzymes for biological recycling, this technology is poised to play an increasingly significant role in future plastic recycling and reuse. Wankai New Materials Co., Ltd. is committed to the sustainable development of PET and is actively exploring breakthroughs in PET recycling technologies, including enzymatic recycling. Moving forward, Wankai aims to deliver greener PET polyester materials, contributing to a sustainable circular economy.