Eco-friendly waste management strategies for greener environment towards sustainable development in leather industry: a comprehensive review

Abstract

The leather industry deals with proteinous skin material for the conversion of leather and this generates huge amount of solid and liquid wastes giving rise to pollution that needs to be overcome by introducing sustainable cleaner technologies. This review describes various eco-friendly challenges and major achievements for abatement of pollution in leather processing. Different cleaner technological methods in preservation of raw hides/skins, unhairing, tanning and dyeing operations are discussed here. Cleaner-preservation techniques by using chemicals and biological agents have been developed to reduce pollution problems of salt up to a great extent in leather processing operations. Process intensified operations have helped to achieve better uptake and to manage pollution load. Enzymatic dehairing are implemented to reduce Bio-chemical-Oxygen-Demand (BOD) at the level of 40%, Chemical-Oxygen-Demand (COD) up to 50%. Improved biological methods for bio-degradation of dyes, azo-dyes and their mixtures and to reuse the liquors in the process to reduce the dye pollution load in the effluent streams are reviewed. Nano-Particle polymers and improved retanning materials have been synthesized for high exhaustion of dyeing and retanning properties. Mathematical models predicting kinetics and growth for the above processes are also reviewed. It could be concluded by utilization of these technologies, a possible reduction in pollution loads such as BOD & COD, upto levels of 50% & 40%, could be achieved in leather processing.