Best Available Techniques for Leather Industry

Following are some of the best available techniques that can not only reduce your environmental footprint but can also contribute to increase your process efficiency leading to reduced overall costs.

• Installation of water flow meters at all water supplies and maintain water consumption records on monthly basis
• Insulate the surfaces above 50°C with optimum thickness
• Remove redundant utility lines and optimize the routing of utilities
• Plan evaluation of efficiencies of utilities (Boiler, Generator, Compressors, etc) generation, distribution and utilization on periodic basis
• Inspect the steam, hot water, freshwater, compressed air lines and fittings for any leakages
• Use desalting drums
• Switch to new technology of tanning drums
• Switch from continuous, “running water washes” to batch washes
• Water used in washing hides before the Main Soaking process can be collected and reused in Pre-Soaking.
• The water used in the liming process can be reused in next liming process batch after filtration. The pollution loads up to 70% of Sulfate [S2-] and 93% of Lime [Ca(OH)2] load can easily be reduced, which can contribute in reducing 7% load of BOD and 26% load of COD in overall wastewater at end of pipe.
• Water used in Deliming washing can be collected and reused in Post Liming.
• Water used in Post Deliming & Bating washing can be collected and reused in Pre-Soaking wash.
• Carbon dioxide deliming can be used to neutralized lime it decreases pollution load of effluents if feasible
• Wetback water can be collected and reused in next Wetback lot
• Water from washing of Wetback can be collected and reused in wetback of successive lot
• Reuse of pickling and tanning floats in successive cycles
• Rechroming Water which is drained to waste after completing the process can be collected and recycled back for the rechroming of next lot or can be directed towards in house chrome recovery plant.
• Post Neutralization Washing Water can be collected and reused as Neutralization Water for the next lot.
• Recycle cooling water from Machines like Vacuum Press, Sammying, pumps, compressors etc.
• Curing salt that is attached to the raw hides [Cow, Buffalo] and skins [goat] can be recovered and reused. It is estimated that 50 kg of salt can be obtained from desalting 1,000 kg of raw stock.
• Decrease the amount of salt used to preserve hides by adding some environmentally acceptable antiseptics (boric acid, acetic acid and sodium suplhide) or commercial bactericides based mainly on ethyldithiocarbamate and isthiazolin. Pollution load in soaking wastewater is reduce to 50%.
• Processing of green hides (unsalted fresh hides) is preferred if cooling and chilling is feasible.
• Dyes containing hazardous heavy metals such as lead, cadmium, and chrome VI shall be avoided.
• Fat liquoring agents based on chlorinated paraffins shall be avoided and other environmental friendly synthetic fat liquors should be used
• Benzidine and other azo-dyes which may be reduced to carcinogenic amines should be avoided.
• Avoid finishing operations with pigments containing environmentally hazardous heavy metals and other restricted products
• Whenever possible use water-based finishes/solvents
• Use of Solar water heating for process water heating
• Use solar air drying for hides and skins wherever possible
• Integration of photovoltaic in existing power supplies available
• Build training routines for staff at all hierarchical levels

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Read further on EU Best Available Techniques Reference Document (BREF)

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