The challenge of tannery residues
Leather production is intrinsically linked to circularity at the raw material stage, as raw hides and skins used by the tanning industry mainly come from the food chains of cattle, sheep, goats and pigs. At the same time, tanning is a complex industrial process that generates significant residual streams: it is estimated that less than 30% by weight of raw hides is converted into finished leather. The residues include a variety of materials: Animal By-Products (ABPs), such as hair, fleshings, and other solid outputs from the early stages of processing, and tanned waste, such as shavings and trimmings from crust or finished leather. The proper management and valorisation of these residual streams are not marginal technical matters but structural sustainability challenges for the leather value chain. Quantitatively, untreated leather and collagen by-products are the biggest problem in the leather industry.¹

The recovery paths of tannery residues in Italy
According to UNIC, the Italian Tanners’ Association, for every square meter of finished leather produced in Italy, around 2 kilos of Animal By-Products residues and over 1 kilo of other solid waste are generated.² This data indicates the scale of the issue, considering that Italy produces approximately 100 million square metres of finished leather per year, and that the Italian tanning industry accounts for 67% of total EU leather production.

The Italian tanning industry has long enabled the transformation of production residues from waste into raw materials for other industrial value chains, creating a diversified system of valorisation in which different streams are directed to specialised routes based on their composition and regulatory status. Reference sectors include agriculture, cosmetics, pharmaceuticals, and construction. These supply chains have enabled significant reductions, or even elimination, of some of the most significant types of tanning waste.

Circular models to produce fertilisers and bio-stimulants
One of the most established recovery routes for collagen-rich tannery residues is the production of fertilisers and bio-stimulants, transforming protein-rich animal by-products and leather processing residues into hydrolysed proteins.  

SICIT Group S.p.A., headquartered in the Arzignano leather cluster, is a prominent example in this field. Back in the 1960s, following public health concerns about the spread of tanning residues on agricultural land, the company became a specialised actor and a global leader in their treatment, transforming leather tanning residues into protein hydrolysates used mainly as biostimulants for agriculture and as additives for the construction industry. Today, the company operates as a large, specialised circular-economy company, with EUR 125 million  in revenue (doubling from 2020),³ two active production plants in Italy and one in Mexico, plus another one in Chile dedicated to the production of seaweed extracts, sales in over 80 countries, all of which confirm its growth trajectory. The scale of its material recovery is significant: the company specifically reported removing around 155k tonnes of animal products from tannery residues streams and incorporating them into its production process in 2024  (+6% on 2022).⁴ This is particularly relevant because the company's services provide tanneries with an alternative to landfill, destruction, or other environmentally damaging or economically disadvantageous treatment options. The collection services are carried out within very short timeframes, as some of these materials are subject to rapid deterioration. In this context, SICIT can leverage its proximity to the tanneries, as it is located within the same industrial cluster.

ILSA S.p.A, operative in the Arzignano cluster and founded in 1956, is another example. ILSA’s relevance to tannery residue recovery stems from its long-standing and specialised expertise in transforming, through hydrolysis processes, collagen-rich materials into agricultural bio-stimulants and fertilisers. The company is one of the few Italian companies with its own accredited in-house laboratory, employs 73 workers and generates a turnover of around EUR 28 million (data for 2024).⁵ The company has two production facilities, one in Arzignano and the other in Molfetta, in the province of Bari, and thanks to a network of partners and retailers, its products are present in more than 50 countries worldwide.

Conclusion
The recovery of tannery residues reduces disposal pressures for tanneries, creates value from collagen-rich biomass, and supports the development of bio-based products. In this context, tannery residue recovery is relevant not only for waste management but also for resource efficiency and the competitiveness of the leather ecosystem. The Italian long-standing experience shows that these systems require specialised technologies, stable relationships between tanneries and recovery operators, regulatory compliance, quality control, and sufficient industrial scale. 

^{1. Chojnacka, K., Skrzypczak, D., Mikula, K., Witek-Krowiak, A., Izydorczyk, G., Kuligowski, K., Bandrow, P., & Kułazyński, M. (2021). Progress in sustainable technologies of leather waste valorisation as solutions for the circular economy. Journal of Cleaner Production, 313, 127902. https://doi.org/10.1016/j.jclepro.2021.127902}

^{2.UNIC  Italian Tanning Industry Sustainability Report 2024}

^{3.Orbis database, Bureau van Dijk / Moody’s Analytics.}

^{4. SICIT Group Sustainability Report as at 31 December 2024}

^{5.Orbis database, Bureau van Dijk / Moody’s Analytics.}