Production of Glue from Tannery Effluent by Physical, Chemical and Biological Methods

Abstract

The meat industry provides the tanner with hides (raw material) which is considered as one of the by- product of the industry. Much greater amounts of wastes and by-products are produced during tanning compared to the production of leather. About 600 kg of solid waste (by-product) and only 200 kg of leather is produced by 1 ton of wet salted hides. There are about 1500 tanneries in India which process 0.7 million metric tons of wet salted hides and skins per annum and produce tannery effluent (TE) of about 30- 50 m3 and limed fleshing (LF) of about 200 kg for every ton of processed skin or hides into leather. In India, around 150000 tons of tannery waste in the form of raw hides and skins trimmings, LF, hide splits and chrome shavings are generated per annum4,7. In the manufacturing process of glue, one ton of beamed fleshing (25% moisture) gives 150 kg of glue. Dechroming of tanned chrome shavings is carried out by various chemical and physical methods: chemical, thermal and biological degradation was utilized to produce gelatin. Hydrolytic agent (acid/alkali) highly influences the final quality of gelatin. The differences between acid or alkali-based hydrolysis have been determined6.No gel strength and low molecular weight fragments were shown by the products that were obtained by alkali hydrolysis, whereas good physical and chemical properties in terms of swelling, thermal stability and gel strength were shown by the gelatin products obtained through thermal degradation.