Environmental assessment of water, chemicals and effluents in leather post-tanning process: A review

The leather industry has significant consumption of water and chemicals and generates liquid effluents with a high pollution load. This study aims to contribute to the advance of liquid effluents, water, and chemicals management in tanneries since the assessment of these environmental issues for each step of the post-tanning process remains unknown. Forty-three post-tanning formulations were obtained from scientific papers, catalogs from chemical manufacturers and tanneries, and their data were analyzed. Results showed an average chemical consumption of 360.2 kg per ton of shaved leather. Retanning and fatliquoring steps are the largest chemical consumers. The average water demand of this process is 8.6 cubic meters per ton of shaved leather, with washing responsible for the highest consumption. The raw wastewater is poorly biodegradable, with high conductivity and elevated concentration of salts. The results obtained in this study contribute to reduce the environmental impacts of leather post-tanning, guiding future studies aiming to optimize this process.