Cleaner Technology for Leather Production Rawstock Preservation Beamhouse Processing Tanning Operations Post-tanning Operations Finishing Operations Waste Minimisation and Good House Keeping In order to reduce the ecological impact of leather production, industrialised countries applied cleaner technologies including waste minimisation and good housekeeping techniques at various stages of leather manufacture. The technologies introduced below are not just to consider as latest development from research units but being used on an industrial scale in European and North American tanneries. Rawstock Preservation Treatment of fresh hides and skins is the best solution to reduce salt pollution. Time elapsing between slaughtering and further treatment (e.g. beamhouse processing) must not exceed a few hours. Beyond this period, it is necessary to cool the hides and skins, either in ice or cold air…… The use of antiseptics with low effect on the environment can help to increase storage time of fresh or chilled hides and skins. Suitable preservatives include: TCMTB, Isothiazolone products, potassium dimethyl dithiocarbamate, sodium chlorite, benzalkonium chloride, sodium fluoride and boric acid…… Beamhouse processing Apart from the use of less harmful antiseptics, a real clean technology that could be applied at this stage is the fleshing of green hides after soaking. Compared to a classical “hair-dissolving” process, 30 to 50 % of COD reduction, in beamhouse effluent, can result from enzymatic or another hair saving treatment…… Tanning Operations Chromium tanning salts are used today in 85 % of tanning processes. If its concentration in waste exceeds an acceptable level (about 1 g per kg dry solid), it strongly limits any possibility of upgrading, or disposing of the waste at an acceptable cost…… Post-tanning operations Post-tanning operations includes re-tanning, dyeing and fatliquoring. When the use of chromium is required for retanning operations, the same consideration should be given as for chrome tanning. For dyeing, some azo-dyes containing carcinogenic amino-components like benzidine, have also to be banned from tannery. Fatliquoring oils used in the tannery are often composed with chlorinated alkan sulphonates and fatty acid methylester sulphonates that are now questionable because of the organic halogen quantities they can generate. As a result of the regulations on absorbable organic halogens AOX, the chlorinated fatliquoring products will be replaced. Various substitutes are on the market to satisfy new laws in this field. Finishing Operations The use of water based finishes is fundamental for a cleaner process. Pigments must not contain any environmentally risky heavy metal or other restricted products. Waste Minimisation and Good House Keeping Four Main Principles of Waste Minimisation – 4R Replace, Reduce, Reuse, Recycle Water Management Through good management, water use can be reduced by 30-50% to 25 liters per kilograms (L/kg) of raw material.