Why 23.8 billion pairs of shoes are almost impossible to recycle

The footwear industry has no credible end-of-life system. Less than 1 percent of discarded shoes are recycled globally. The first large-scale material analysis of European post-consumer footwear shows why — and what would have to change.

Design complexity is the primary barrier

A shoe is not a garment. While 93 percent of non-rewearable apparel is mono-layered and sortable, post-consumer footwear arrives as a tightly assembled, multi-material object held together by industrial adhesives designed not to come apart.

An analysis of 1,200 non-rewearable post-consumer shoes gathered at a sorting facility in Catalunya, Spain — the largest product-level dataset of its kind — found that 52 percent were bonded with permanent adhesives and only 19 percent were stitched. Just 10.5 percent used the same material in both the midsole and the outsole.

That construction logic breaks the recycling chain at the first step. Recycling requires material identification. Identification requires separation from everything the material is bonded to. Neither happens at industrial scale today.

Near-infrared (NIR) scanning, the backbone of automated textile sorting, adds another constraint. The technology reads reflected light, but carbon black pigments — used in most dark soles — absorb the infrared spectrum rather than reflect it. In the Catalunya sample, 97 percent of black soles returned an unknown material classification. Since 24.6 percent of all soles were black, more than a fifth of the sole stream became unidentifiable before disassembly began. Across the full sample, 37 percent of sole materials could not be identified and 17 percent of upper materials remained unknown.

The study, conducted by Circle Economy and Fashion for Good, tested two near-infrared scanner prototypes developed by Matoha, alongside X-ray capability from CETIA’s SensorHub and image capture via IDShoes. More than 60 percent of materials were successfully identified, a meaningful baseline for a first attempt to apply this technology to footwear at scale.

The carbon black constraint is now a clear technology gap, and dedicated sensor development is underway.

The non-rewearable stream: what is actually discarded

Of the 7,200 items sorted at Modare Koopera in Barcelona, 60.2 percent were classified as rewearable, 34.7 percent as non-rewearable and 5.1 percent as contaminated. The study drew its 1,200-item analytical sample from the non-rewearable fraction.

Within that fraction, 76 percent showed some form of visible damage — predominantly aesthetic rather than structural. Soiling accounted for 50 percent of upper damage and discoloration for 27 percent. Structural failure of the sole — detachment or tears — appeared in only 9 percent of cases.

But 24 percent of non-rewearable shoes showed no physical damage at all. These items failed reuse qualification for systemic reasons, including the wrong archetype for current second-hand demand or arriving as single shoes without a pair. A quarter of the waste stream was not broken. The system had nowhere to put it.

Archetypes also matter for recyclability planning.

Lifestyle shoes (trainers, slip-ons) dominated at 37.5 percent of the sample, followed by sandals (25.2 percent) and slippers/slides (14.9 percent). Performance shoes accounted for 11.2 percent. The two most recyclable archetypes from a material yield standpoint, lifestyle and performance, show consistent material patterns: ethylene vinyl acetate (EVA) dominant in midsoles, and rubber/styrene-butadiene rubber (SBR) dominant in outsoles. The 8 Impact, which contributed a parallel 2,000-pair sneaker recycling pilot to the study, demonstrated closed-loop viability for this stream at pre-industrial scale, achieving up to 40 percent recycled content in validated compounds without compromising mechanical or toxicological performance.

The export system is not a solution

Of collected and sorted footwear in Europe, roughly 90 percent is exported to second-hand markets in Asia and Africa, with Pakistan the leading global importer. The primary economic driver is avoidance: domestic incineration costs in Europe are high enough that export remains the path of least resistance for low-grade material, even when end-market absorption is uncertain. An estimated 5 to 6 percent of what arrives in Pakistan cannot find use after a second round of sorting and ends up incinerated or discarded through uncontrolled disposal.

The implicit circularity in these informal markets is genuine and operates at real scale. It is also uncompensated by any European sustainability investment framework, and it carries the residual burden of material that Europe was unable or unwilling to process at home.

The report does not prescribe a policy response to this dynamic, but it names it: export is waste management, not circular recovery.

Technology pilots: what works, what does not yet

PICVISA’s automated NIR sorting trials using shredded feedstock pre-processed by Eldan Recycling identified rubber as the most reliably recoverable polymer. Rubber achieved 19.7 percent recovery versus 18.5 percent in manual identification, validating its stability in automated systems. EVA and thermoplastic polyurethane (TPU) both lost yield after shredding, falling from 33 percent and 14 percent in manual identification to 6 percent and 5 percent respectively. These polymers are likely reclassified as lightweight fractions during shredding, a technical bottleneck that preprocessing design will need to address.

Material losses through the mechanical recycling process ranged from 25.5 percent for boots to 73 percent for performance shoes, where high textile concentration meant most of the material was classified as light fraction and lost during density separation.

France shows what enabling policy looks like

One EU member state has built the infrastructure and regulatory conditions for footwear circularity to function. France operates a mandatory Extended Producer Responsibility (EPR) scheme that covers textiles, household linen, and footwear as a unified stream under Refashion, the designated producer responsibility organization. Brands and importers finance collection, sorting, and treatment.

The result: 90 percent of collected footwear in France is reused. Refashion has additionally supported CETIA’s SensorHub development, the ZAPATEKO II project on recycling obstacles, and published a Best Practice Guide on footwear design for recycling.

Under the revision of the EU Waste Framework Directive (2025), EPR for footwear is to be implemented EU-wide by April 2028, requiring each national producer responsibility organization to include footwear sorting. Footwear is not yet covered by the Ecodesign for Sustainable Products Regulation (ESPR); a sustainability assessment is scheduled for completion by 2027 under the 2025–2030 working plan.

The strategic playbook

For established footwear brands and retailers

The research identifies circular design as the leverage point with the highest systemic return. Interventions include replacing permanent adhesives with reversible bonding or mechanical fasteners where performance allows. Brands can also eliminate decorative disruptors (logos, overlays and patches) that add no structural function, avoid carbon black pigments in soles where alternatives meet performance requirements, and implement Digital Product Passports to support material traceability ahead of ESPR compliance deadlines.

On the service side, the finding that 24 percent of discarded footwear shows no physical damage supports brand-operated cleaning, repair and take-back infrastructure. The economics are more defensible for higher-value lifestyle and performance archetypes than for fast-fashion casual footwear, but the infrastructure investment applies across categories.

For recycling innovators and infrastructure operators

The priority feedstock for near-term economic viability is the lifestyle and performance shoe stream, where rubber and EVA yields are most consistent and where archetype-based pre-sorting is feasible. The 8 Impact pilot shows that pre-industrial closed-loop production is technically achievable within that stream. Scaling requires offtake commitments from brands. The report is explicit that recycling economics remain fragile without demand-side signals from large buyers.

Preprocessing capacity (cutting, sole separation and contaminant removal) is the missing link between collection and recycling at scale. No industrial-scale facility for footwear disassembly currently exists in Europe. That gap is both the primary constraint and the primary investment opportunity.