Leather industrial effluent and environmental concerns: a review

The tannery industry is one of the most pollution-generating and environmentally unfriendly industries in the world. The study aimed to assess the current state of physicochemical features of leather effluent and explore environmental pollution concerns for human health. It consolidated all the available data on leather effluent characterization collected from various journals, newspapers, and websites of about 100 papers published in the last 30 years. The review analysis illustrated that almost every tannery industry uses notable amounts of chemicals to transfer animal hides into leather. Beam house operations produce 75% of the total chemical oxygen demand (COD) and biological oxygen demand (BOD) load, and tanning operations produce 70% of the total chrome load in the effluent of a complete leather process. About 40% of the unused chromium salts were discharged as the final tannery effluents, and 30% of leather industrial effluents contained chromium (VI). The result showed that the values of some physicochemical parameters of the Asian and African countries for leather industrial effluent, such as electrical conductivity (EC), BOD, COD, total dissolved solids (TDS), total suspended solids (TSS), chromium (Cr), and sodium (Na), are significantly higher than the tolerance limits for industrial effluent discharged into land surface or public sewers. The pollutants cause harmful effects on water, soil, plants, and human health. A modern and effective Effluent Treatment Plant (ETP) of combined treatment facilities should be adopted in leather industries to reduce environmental pollution due to untreated leather industrial effluents. Hence, it is imperative to take the necessary oversight and curative measures to reduce pollution and enhance environmental sustainability for the world, particularly in developing countries.