"Leather tanneries pollute the environment"
Let us look at the nature of waste material coming out from the leather processing plants per tonne of
hide processed into leather:
Proteins, sugars and natural fat
These are removed as wastes from the hides. We can not consider them as waste generated by
leather processing, because if the hide is not processed into leather the whole hide will be a waste
material. About 50% of the hide is removed as waste in various forms during processing.
Chemicals in water
Various chemicals are used during leather processing.
Some of them are removed during subsequent operations and some are used in excess quantities and are discharged
in the waste stream.
The focus inside the industry now is to improve the efficiency of processing so that the second category of
waste is totally eliminated. Alternate technologies are being developed to avoid the waste generated by the first
category of chemicals
Due to the increased awareness in and outside the industry many places require tanneries to treat
the water inside the tannery itself to remove all the impurities before the water is discharged outside.
Having said that, let us clarify that the pollution threat presented by tannery chemicals is minimal and ordinary
in nature. The chemicals in question are Chlorides (common salt) and sulphates, lime, fats, vegetable material, organic
material and so on. One major metallic pollution is chrome which is found to be harmless in the form it is released
from tanneries.
Air pollution
The odour associated with tanneries is mainly due to the rotting proteins which will still be there if the hides are left
to rot on their own. A few years back use of solvents for finishing on the leathe surfaces and for removing natural grease
from the skins was prevalent. Agains, due to the improved awareness these processes are replaced with water based
technologies and are no longer a threat to the environment