Leather manufacturing is classified as water-, energy- and waste-intensive by the Industrial Emissions Directive (2010/75/EU). Tannery effluents, if not properly treated, cause significant damage to soil and water bodies. Over 85% of world leather production involves the traditional chrome tanning process (TCTP). The use of chrome (Cr) in the industrial processing of animal hides poses serious environmental and health problems due to the use of hazardous chemicals, the production of solid/liquid waste and air emissions, and the formation of hexavalent chromium in finished articles.
In Italy alone, the tanning industry uses 47 million tonnes of chemical products per year (2011 figures). Nearly 31% of products contain substances classified as hazardous, according to the CLP Regulation ((EC) No 1272/2008). Around 125 million m2/year of leather in Italy are TCTP tanned, consuming approximately 145 million m3/year of water. Moreover, at present (2022 figures) in the pilot area of the tanning district of Vicenza, effluents are sent to wastewater treatment plants for an average cost of 4 EUR/tonne for waste water treatment (including the acqueous purification and sludge treatment) and to landfills, with an average cost of 20 EUR/tonne for leather shavings and 50 EUR/tonne for leather trimmings.
The main aim of the LIFE GOAST project was to demonstrate the benefits of a new tanning technology on a semi-industrial scale. The technical feasibility of the technology, as well as its social and economic impact, would be monitored and compared with the TCTP in order to demonstrate the reduced environmental impacts of the new process, while producing comparable or better quality leather.
In particular, the project would:
- Produce chrome-free high quality leather articles;
- Improve the quality of tannery effluents by eliminating chromium salts, mineral acids/bases and sodium chloride in tanning and re-tanning steps;
- Demonstrate, in a pilot plant on a semi-industrial scale, lower environmental impacts in terms of reduced hazardous substances, primary resource consumption (water), and environmental releases into water and soil; and
- Eliminate/reduce chrome-containing sludge.
The LIFE GOAST project developed and validated on a semi-industrial level an innovative chrome-free tanning technology. The metal-free GOAST tanning agents, which were optimised under the project, reduce the environmental impact of the tanning process and increase its circularity by enabling scraps and shavings to be recycled through a pyrolysis process as an additive for cement, filler for lithium batteries, bio-oil fraction for asphalt production and support substrate for heterogenous metal-based catalysts, among other applications.
The project team installed pilot plants for tanning agent production and wastewater treatment tests.
The tests were carried out on around 75 tonnes of hides use in the automotive, upholstery and footwear sectors, with the quality of the wastewater from the tanning process monitored for COD, heavy metals and other harmful chemicals, as well as the possible inhibition of the biomass used for waste-water treatment.
A key outcome of the project was the development of a business plan for the commercialisation of the GOAST tanning agents and leather. The improved sustainability of the leather goods produced attracted much interest among established car manufacturers such as Bentley and Mercedes.
Specifically, the environmental benefits included:
- Complete elimination of chrome salts and Cr-VI from the tanning process and tanned hides;
- 95% reduction in the health risk thanks to the use of less harmful chemicals; and
- 15% decrease in water consumption, mostly linked to the re-tanning phase in the GOAST process.
Finally, the project identified a tendency to overlook the toxicity and health effect indicators in the environmental impact assessments of products in the tanning sector. In particular, the Product Environmental Category Rules for the tanning sector did not include the toxicity and health indicators among the most relevant ones for PEF analysis, thus potentially leading to an underestimation of the negative impact on health of chrome tanning and stalling the phasing out of this method of tanning. The project can also be considered to have contributed to the following legislation:
- Directive on Integrated Pollution and Prevention Control (2008/1/EC);
- Waste Framework Directive (2008/98/EC), for hazardous waste and circular economy;
- Water Framework Directive (2000/60/EC);
- REACH Regulation; and
- End-of-Life Vehicles Directive (2000/53/EC).
Further information on the project can be found in the project's layman report (see "Read more" section).