Recovery and Utilization of Chromium-Tanned Proteinous Wastes of Leather Making: A Review

Abstract

Hides and skins, by-products of the meat industry, are converted into a value-added product, leather, by tanners. Tanning essentially is the process of converting raw hides and skins into an 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 a 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 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 a number of size-reduction, leveling, and purification operations are carried out, which results in generation of untanned and tanned proteinous waste materials. The authors review various recovery processes and utilization methodologies of chrome-tanned proteinous solid wastes emanating from leather processing operations.