Progress in sustainable technologies of leather wastes valorization as solutions for the circular economy

Abstract

The tanning industry generates a large amount of waste, which should be managed following the principles of the circular economy. It is estimated that leather processing produces 200 times more waste than total product output. This paper presents a review of the methods that offer recycling of materials or energy from tannery waste, including chemical, thermal and biological techniques. These processes can recover a number of secondary feedstocks such as chromium, nutrients, collagen hydrolysate, fat, biogas, and anaerobic digestate, which can be used in other industrial processes. The review also covers the current legislative status of waste and its impact on the environment. Smart and sustainable valorization technologies enable a high degree of recycling with no burden on the environment. • Valorization of tannery waste will reduce the problem of residue disposal. • Recovered chromium can be returned to processes in the tanning industry. • Leather waste is a valuable source of proteins and lipids. • By-products from tanneries can be used as a renewable energy source (biogas, biofuels).