End of life in the natural cycle

External scientific approval of biodegradability

A study conducted in 2021 by the University of California’s prestigious Scripps Institution of Oceanography (SIO) compared the degradation processes of nonwovens made from fossil-based synthetic materials, such as polyester, with those of cellulosic materials, derived from the raw material wood, such as LENZING™ Lyocell fibers in specific scenarios¹. It was shown that cellulosic fibers can degrade under oceanic and aquatic conditions within 30 days, while the fossil-based fibers tested were practically unchanged after more than 200 days. The research was the result of an independent project aimed at understanding the end-of-life scenarios for textiles and nonwovens.²

Furthermore, a range of Lenzing fibers was tested for biodegradability at the independent research laboratory Organic Waste Systems (OWS) in Belgium. The assessment was performed in accordance with existing and applicable international standards, reflecting all relevant natural and artificial environments where biodegradation can take place (figure “Biodegradation of fibers in various environments”). Certificates from the certification organization TÜV Austria show that TÜV certified biodegradable and compostable LENZING™ fibers biodegrade in soil, fresh water and marine environment and are compostable in home applications and industrial facilities³. This should not be seen as a way to litter or as a justification for littering, but rather as an additional protection to prevent pollution. For more information, please see “End of product use” focus paper.

Biodegradation of fibers in various environments^a

End of life of Lenzing’s fibers

Looking at the end-of-life stage for products manufactured from Lenzing’s fibers including clothing, home textiles, technical products, hygiene products and personal care products, there are several processing options:

• Recycling: Products made from cellulosic fibers can in principle be recycled and used again for fiber production at Lenzing.
• Compostability: If recycling is not possible, some textile and nonwoven applications can be composted if all constituents are biodegradable. The BioSinn report⁴ (funded by the German Federal Ministry of Food and Agriculture) from the Nova-Institute lists such applications – including wet wipes or binding yarns. TÜV certified biodegradable and compostable LENZING™ fibers are compostable, fulfilling the requirements for compostability in terms of biodegradability, disintegration and absence of eco-toxicity.⁵
• Anaerobic digestion: Alternatively, for certain products it may be appropriate to use anaerobic digestion with energy recovery (biomethane production) in waste treatment. LENZING™ fibers are fully degradable in controlled anaerobic waste treatment conditions.
• Incineration: If composting is not an option, the final products can be incinerated and the embedded energy recovered. Since the fibers consist of natural polymers, they are climate-neutral in terms of incineration, which means that only the amount of CO₂ initially stored in the plant is released. Either way, both composted materials and CO₂ provide input for plant growth, thereby closing the natural carbon cycle.
• Landfill: The least preferable option for materials’ end-of-life is landfill, which is still a regular practice in many countries.

Fiber types on the world market^a

Cellulosic fibers

Cellulose is a major component of plant biomass and one of the most abundant polymers produced in nature. The natural cellulose cycle builds the basis for Lenzing’s business model. When the carbon from the materials is released at the end of their life, this renewable carbon and part of the natural cycle, ensuring that no additional fossil carbon enters the atmosphere. Lenzing fibers are produced from natural cellulose in an industrial process. The results are (regenerated) cellulosic fibers such as viscose, modal and lyocell. Figure “Fiber types on the world market” shows that two groups of fibers consist of unmodified natural polymers: natural fibers, and regenerated cellulosic fibers derived from the raw material wood. Both groups of fibers are inherently biodegradable. Other fiber types can be difficult to biodegrade, such as conventional fossil-based synthetics, some of the biosynthetic fibers, and some semi-synthetic fibers made from chemically modified natural polymers. For a systematic overview of fiber biodegradation, see the “Biodegradable Polymers in Various Environments” chart compiled by the Nova Institute.

¹ Degradation of synthetic and wood-based cellulosic tissues in the marine environment: comparative evaluation of field, aquarium and bioreactor experiments.

² New studies regarding the biodegradability of Lenzing fibers have been conducted in 2022, but have not been published yet.

³ LENZING™ FR Standard and LENZING™ FR Black are only industrial compostable. LENZING™ Lyocell Filament were not tested for marine biodegradability and LENZING™ Lyocell Dry is not compostable in salt water.

⁴ BioSinn – Products for which biodegradation makes sense (PDF) | Renewable Carbon Publications (renewable-carbon.eu)

⁵ Ellen MacArthur Foundation, 2017. A new textiles economy: Redesigning fashion’s future, http://www.ellenmacarthurfoundation.org/publications, p. 21