Toxic hazards of leather industry and technologies to combat threat: a review

Leather industry has significant economic influence; however, it suffers from the negative impact due to environmental pollution caused by tannery wastes produced during leather processing processes. The tanning processes contribute significantly to chemical oxygen demand (COD), total dissolved solids (TDS), chlorides, sulfates and heavy metal pollution. The chemicals discharged into aquatic systems end up in highly polluted sediments and salinisation of rivers. European Chemical Agency (ECHA) has prioritized some of the hazardous chemicals used in leather under Substances of Very High Concern (SVHC) and substances for Authorization. The situation has highlighted the need for greener technologies. Out of the two broad categories of technical methods, the first group involves the introduction of processing technologies by decreasing the effluent pollution load, avoiding the use of harmful chemicals and producing solid wastes that can be used as by-products. The other category is related to the treatment of wastewater, handling and processing of solid waste in an environment-friendly manner. Both methods have been applied to prevent negative impact on the environment during leather production. The methods have been reviewed for their technical suitability and commercial feasibility and it was felt that combination of both is essential. The technologies can have up-front additional costs but have to be balanced against multiple benefits in terms of environmental cleanup, improved labour productivity, material quality consistency and better international image. By using the best available technologies and optimized systems the leather industry can evolve as an environment friendly technology.