Shoe Recycling Challenges and Prospects

Shoe Recycling: Technology for Effective Separation Exists

The worldwide shoe recycling industry has not kept pace with recycling advances in other sectors. Statistics suggest that every year more than 20 billion plus pair of shoes are produced worldwide. And it is believed by industry experts that currently at best 5 percent of end of life footwear products is recycled. The good news is that progress is being made. In recent times, a number of footwear manufacturers have started recycling and using recycled content in their footwear products.

Additionally, efforts are being made by researchers to find better ways for recycling shoes both from economic and practical perspectives.

The Major Challenge

Cost-effective and efficient separation of components used in footwear products is the single major challenge confronted by the shoe recycling industry, one that can be addressed by effective design for recycling. Leather, fabric, rubber, foams and metals are some of the most common components used in footwear products. Especially the presence of metal components in footwear products makes it very difficult to recycle. That is why director Professor Shahin Rahimifard, the director of UK’s Loughborough University-based Centre for Sustainable Manufacturing and Recycling Technologies, known as the Centre for SMART (www.centreforsmart.co.uk), recently stated that footwear is incredibly difficult to recycle as it can contain a number of different types of material with very similar characteristics, many of which are stitched or glued together.

Focus on Elimination of Metal

To make shoe recycling easier, footwear manufacturers need to give maximum focus on designing footwear products keeping recyclability in mind. Rahimifard describes shoes as currently being ‘an imperfect product’ for recycling. The removal of certain materials from their design would mean fewer processes required to achieve good-quality recycled materials, thus making recycling both ‘simpler and more viable’”.

Regarding the use of metal in footwear products he stresses that metal in shoes makes recycling more difficult. While the common perception is that metal adds value when it comes to recycling, this is not the case in shoes because it is in such small amounts and is usually encapsulated deep within other materials.

A Comprehensive System Has Been Developed

The shoe recycling industry needs a comprehensive system to process used footwear. And the Centre for SMART’s research team has already made and successfully tested a comprehensive system that needs to be implemented. The system proposed by the research team has been described as ‘the world’s first comprehensive system for separating and recovering useful materials from old footwear.

The initial step of the comprehensive system is to presort various types of shoes based on the major contents, such as leather based shoes, for example, and separating metals like the eyelets through which laces are threaded. After the major materials have been separated, newly developed low cost, air-based technologies separate the materials further by exploiting their different weights and sizes. In the process, an air-cascade separator takes away lighter textile particles and other fine foam and leather residues.

Then a chain of vibrating air tubes splits the rubber from leather and foam by stratifying the granulated content, with comparatively lighter granules finishing up on top of the heavier  granules. The optimal granulated unit size has been found to be 3-5 mm. Any bigger and the fragments could stay stuck to other items of a dissimilar content, thus compromising recycling.

With respect to the technology Rahimifard notes that the problem is no longer with the technology but with the system level issues, saying that the technology can be applied to any type of shoe. Economic viability depends on other factors such as throughput rates, reverse logistics costs and revenues from recycled materials.