Context: Circularity has become a key concept in sustainability. It's crucial to reduce virgin resource extraction and maximize the value of what's already been extracted. The Circularity Gap Report identifies four key circular principles: use less, use longer, use again, and make clean. Innovation will drive the transformation of traditional industrial practices into circular business models.
Leather + Circularity: Industries that use leather as their raw material, such as automotive seating, upholstery and fashion, have begun shifting from a linear production cycle to a circular one as consumers are becoming increasingly aware of the environmental damage caused by waste generated. Specifically, within the leather industry, concerns over using the skins of animals have caused the explosion of start-ups generating leather from unique sources, both natural and synthetic methods. And so, while the industry is slowly edging towards circular models, alternative leather is closely competing against traditional leather. Experts are holding on to the hope that unique innovative methods could create a much more sustainable circular leather industry compared to alternative leather manufacturing.
3 Source of Waste: Within the lifecycle of leather, from raw material to production to final consumer usage and discard, there exist three main sources of waste. The first is tannery waste, which is chemicals like tanning agents being expelled along with the large amounts of water used. The second is manufacturing waste which includes waste leather material after cutting, and other post-tanning and finishing chemicals that are expelled. And the final waste form that leather exists in is the post-consumer waste, which is generated at the end of its lifecycle. There has been research activity and innovation to convert each resource into a useful product that can be either put back into the production cycle or sold as another product.
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Tannery Waste: Tanning effluents are infamous for being the leading cause of pollution from the leather manufacturing industry. Nearly 200 liters (about twice the volume of a mini fridge) of wastewater containing toxic chemicals are generated per kg of leather manufactured. Many studies have been conducted for novel ways of extracting or separating these chemicals from the wastewater or the leather itself so that they can be reused in the production cycle by creating a ‘virtuous cycle’.
One such research study has been conducted by Universidade Federal de Santa Maria, on efficient separation of chromium from residual tanned leather at mild reaction conditions. CSIR has also researched converting used tannery fleshing wastes to prepare value-added chemicals like re-tanning agents.
Manufacturing waste: Start-ups that have developed unique products from the wastes generated from leather manufacturing include Phoenix Italy. They launched a project named L-WARE (Leather – WAstes’ REbirth) through which a patent was developed that converts chrome and heavy metal leather wastes into a material that can be used in manufacturing active carbon filters.
Another unique product created from post-consumer leather is fertilizer. Ecotan, a start-up based in Italy, along with their partner Fertilizzanti Certaldo, has developed a technology that converts leather into fertilizer. However, the leather must be made by Ecotan or manufactured using Ecotan tanning products.
Post-Consumer waste: Recyc Leather is a start-up that converts leather products like gloves into luxury goods. Leather scraps are generated when cutting leather into specific shapes for products like gloves. These scraps are shredded and mixed with natural rubber, and the mixture goes into the bonding machine. The resulting sheets are then printed to the desired texture and grain and then converted into products for different applications like packaging, footwear, automotive, etc.
HKRITA, a research institute based in Hong Kong, has developed a process to remove chromium from processed post-consumer leather. The separated leather fibers are then made to react with biobased binders like sugars or protein as opposed to synthetic ones like PU or PVC, under mild conditions resulting in the fibers reconnecting to form a new leather. The resultant leather is water-resistant and biodegradable.
Verdict: The world is becoming more circular with a focus on sustainability. The leather industry must invest in developing technologies to extend the life of leather and its manufacturing chemicals to join this global trend.