Tannery: Environmental impacts and sustainable technologies

The tannery is an old industrial sector well-developed, plays an important role in the global economy, and has been heavily industrialized over the years in all countries. In developed countries, the legislation forces the tannery sector to develop clean and sustainable production. Due to the strict legislation policies, there was a continuous change in the distribution of the processing sites. There are two main reasons for this shift of the distribution, namely: 1) lower labour costs in some countries than in others; 2) fewer environmental restrictions in some countries than in others. The current tanning process is still mainly based on the traditional one, making use of chromium salts and being able to give leather of very high quality, despite its severe environmental drawbacks. Since its industrialization, the tannery has shown its heavy environmental impacts, caused by the operations and the processes done in the productive/supply chain, from the raw hides and skins to the final leather. Especially, this sector consumes a huge amount of water, which generates wastewater with high concentrations of pollutants (mainly, chromium(III), sodium sulfide, ammonium chloride, biocides, aldehydes, dyes, etc.). Emissions to the air and solid waste production are worth of consideration, too. At last, the health effects on the workers can give problems in the short as well as long term. Looking at the current distribution of the processing sites, most are in developing countries, where the legislation is still weak. Little amounts of leather derive from the green tannery, where the use of chromium is limited or completely avoided. The reason is the lower quality of the leather produced by the so-called ‘‘green technologies”. This paper analyzes the impacts deriving from the tannery industry due to the conventional chromium process. The reduced-chrome processes and green technologies are discussed, too, considering the role of nanotechnologies.