Environmental protection and tanning processes

Different tanning processes

The most common tanning methods are chrome tanning, vegetable tanning, and synthetic tanning. Chrome tanning involves tanning the leather with chromium (III) salts, making it a chemical tanning process. Vegetable tanning requires only plant-based materials, such as tree bark. Synthetic tanning agents are artificially produced substances, such as formaldehyde, that are used in tanning. Typically, a combination of different tanning processes is used to achieve specific leather properties.

Tannins Environmental protection Ecology

Chrome tanning and environmental pollution

The chromium (III) salts used in tanning are inherently harmless. However, oxidation to chromium (IV) poses a problem. This is a heavy metal that is considered allergenic in small doses and carcinogenic and extremely toxic in high doses. Improper disposal of the tanning agent further pollutes the environment, leading to salinization and high levels of heavy metal contamination in the soil. Chromium often enters waterways, where it is highly toxic to fish and microorganisms. Currently, approximately 85% of tanning worldwide is carried out using chromium salts.

Vegetable tanning and environmental pollution

Vegetable tanning is a natural process. Tannins derived from plants are used for tanning; these are water-soluble and biodegradable.
However, tanning requires a large amount of tanning agent, and in some regions, it results in significant depletion of certain plant species. Furthermore, improper disposal can lead to organically contaminated wastewater.

Environmental protection vegetable tanning

Synthetic tanning and environmental pollution

The synthetic tanning process is rarely carried out in isolation, but in most cases in combination with one of the other two processes.
Since synthetic substances are not naturally derived, they are also not biodegradable. Their environmental impact depends on the individual substance. However, they cause significantly less environmental pollution than chromium salts.