Raw effluent from tannery contains the wastes and chemicals released during the washing, de–hiring and process of leather, which are the concerns for the leather industry.
Now they have been taken care of by adopting the new method of salt less pickling, use of enzyme in the process and the costly Membrane Technology and Reverse Osmosis system in the leather industry which is called “ ZERO LIQUID DISCHARGE” system, recycling and re-using the effluent water from the tannery discharge.
The washing of skins removes dirt, salt and some organic matter from the raw material. Lime and sulfides are used to de-hair the skins. Then de-liming to remove the lime in the skins and soften them by enzymatic action as new and innovative step to reduce the pollution load in the tannery discharge.
The skins are tanned using the chrome tanning process, where the chrome recovery system is adopted to recover 95% of the Chrome. Environmental and health concerns have resulted in a number of initiatives to reduce its presence in the waste stream, improve fixation on the leather, recycle chromium from effluents, and use other harmless alternatives.
In the final processing of the leather, colour and fat liquor are employed to colour and oil the leather to make it as soft or as firm as desired.
The Indian government has numerous laws in place that keep the leather industry always compliance to the latest environmental norms. State Pollution Control Boards have in the last few years taken stern action and even ordered closures of, and imposed fines on hundreds of tanneries for pollution infractions. Common effluent plants have been a major effort of both Central and State governments, and have been established in all areas of where tanneries are clustered