Recovery and utilization of proteinous wastes of leather making: a review

Hides and skins, by-product of the meat industry is converted into a value added product namely leather by the tanners. Tanning essentially is the process of converting raw hides and skins into imputrescible substance. The tanning process has number of steps and generates significant quantities of by products and wastes. These solid and liquid wastes pose major environmental problem if not managed effectively. Large–scale production systems are adopted for leather processing in clusters and therefore, the industry receives focus of environmentalists and society. Consequently tremendous pressure is exerted by various pollution regulatory bodies. The hides and skins, after trimming, removal of flesh and fat, are treated with chemicals, which cross-link the collagen fibers to form a stable, durable material. The chemicals used may be derived from traditional vegetable products, or inorganic metal salts. During leather processing number of size reduction, leveling and purification operations are carried out which results in generation of untanned and tanned proteinous waste materials. In this paper, various recovery processes and utilization methodologies of proteinous solid wastes, emanating from leather processing operations prior to tanning is reviewed.