What we are doing to the environment is but a mirror reflection of what we are doing to ourselves and to one another
- Mahatma Gandhi
Tanning is the stage in which raw hide is processed into leather and made more durable so that it can be made into various products in the subsequent stages of the industry. Tanning is composed of three stages : the pre-treatment of animal hides, the application of a tanning agent, and finishing the material with treatments such as drying and shining. However, these stages are not static categories, and the overall tanning process can also include sizing of hides, weaving, bleaching, carbonizing and dyeing in addition to finishing.
Tanning is one of the most toxic industries in the world because of the chemicals involved. The tanning process uses acids, alkalis, salts, enzymes and tanning agents to dissolve fats and non-fibrous proteins and chemically bond the collagen fibres together. Brine curing, or brining, consists of submerging the hides in a solution of sodium chloride to which naphthalene may have been added. Hides sent to the tanneries are generally treated with DDT, zinc chloride, mercury chloride, chlorophenols or other agents for disinfection. Disinfectants such as bleaching powder, chlorine and sodium acid fluoride in the water prevent putrefaction of hides. Chemicals such as caustic soda, sodium sulphide and surfactants are added to the water to accelerate soaking of dry-salted or dried hides. Chrome, known for its cancer-causing abilities, is used in huge amounts for tanning as are acids, natrium and ammonium salts. The soaked hides and skins are “limed” by immersing in milk of lime (Calcium oxide) to loosen the epidermis and hair roots and to remove other unwanted soluble proteins and fats. Finally, all these toxins are washed away with tons of clean water. In Kanpur, the home of the largest number of tanneries in the country, this contaminated water, which forms the highly toxic tannery effluent, is being released into the Ganga, the holiest of the holy rivers.
The river water turns particularly toxic at Kanpur due to heavy influx of industrial waste, tannery effluents and city sewage. The total sewage of Kanpur is around 300 mld (million liters per day) and the capacity to treat it is only 117 mld.
Again, Basic Chrome Sulphate (BCS) or chrome liquor (a chemical used in tanning) that contains chromium, a known carcinogenic also ends up untreated in the river along with other tannery effluents like lime sludge. Overall, there are about 700 listed tanneries — besides many unlisted ones (more than 200) — in Kanpur. Of these, 75% use chromium-based systems to process leather. More than 80 percent of the waste water flows unchecked with minimal treatment into the river. According to one estimate 450 tons of toxic effluents are released into the Ganges by the Kanpur tanneries each day.
The virulence of the tannery effluents can be substantially reduced (by nearly 70%) by simply replacing Basic Chrome Sulphate (BCS) with ECOTAN, a proprietary organic reagent developed by Ecohealth Products Pvt Ltd, which has been tested and approved by the Central Leather Research Institute (CLRI), Chennai (Patent applied).
Powder Lime or Calcium oxide used in the liming process leaves behind a sludge that is hard to dispose off. The high degree of sludge produced in tanneries can be substantially reduced by replacing the Powder Lime used in the process with ECOLIME, a sludge-free, eco-friendly liquid substitute, also developed by Ecohealth Products Pvt Ltd. This has also been tested and approved by CLRI. Patent has been applied for.
The resultant, relatively benign tannery effluents can be further purified in Effluent Treatment Plants (ETPs) and treated with small doses of ECOCLEAN-20 and ECOCLEAN-50, which will neutralize most of the other salts and toxins in the effluent water.
This treated water can then be safely released into the Ganges (or any other river, for that matter), without fear of the large scale contamination that now pervades.
Both these products have been tested and certified by the Central Leather Research Institute (CLRI) in Chennai as early as 2005 itself and have been further perfected in nearly a decade of research. Today successful field trials of the improved versions of ECOLIME and ECOTAN have been carried out in the tanneries of Messrs E K Mohammed Ebraheem Sahib & Sons in Erode, Tamilnadu. The details may be verified directly :
ECOTAN : Non-toxic, chrome-free, eco friendly substitute for BCS (Basic Chrome Sulfate) to produce Wet White leathers. Eliminates the necessity to install expensive chrome recovery plants. Simplifies effluent treatment procedures.
ECOLIME : Eco-friendly, sludge-free, liquid substitute for Powder Lime used in the liming process of tanning. Totally eliminates the vexatious sludge disposal problem that is plaguing the leather tanning industry today, pushing several units to the verge of closure.