Toward Sustainable Leather Processing: A Comprehensive Review of Cleaner Production Strategies and Environmental Impacts

Abstract

Although the leather processing industry is vital in terms of employment creation, revenue generation, consumption of by-products from the meat industry, and the production of the valuable commodity called leather, the industry is considered “red marked” due to the discharge of solid, liquid, and gaseous wastes from each unit operation. In addition, different cleaner production options were investigated to mitigate the negative effects of the leather industries. Cleaner options in curing were mostly focused on the use of plant extracts and the sodium chloride-free preservation method, which eliminates the salinity and 70% TDS of the discharged water. The application of enzymes in the soak and unhairing facilitates the operation, reduces COD, BOD, and TDS in the effluent, and yields better results than the conventional method. Saltless and waterless pickling with nonswelling acid and chrome-free tanning was considered cleaner options for pickling with salts and conventional tanning methods. This article provides an in-depth analysis and review of conventional leather processing, hazardous chemicals in each unit operation, the environmental impact of conventional operations from curing to tanning, and cleaner leather production approaches in each unit operation.