Electrochemical treatment for tannery wastewater: emerging trends, and future perspectives

The tanning industry is known to have serious environmental effects, as it consumes a significant amount of water, chemicals and dyes, and the resulting tannery wastewater has high total dissolved solids (TDS), chemical oxygen demand (COD), and chromium species. These pose a threat to the ecosystem and human beings. Conventional treatment methods like coagulation, flocculation, and biological processes show limited efficiency and generate contaminated sludge. Hybrid systems combining flocculation, photocatalysis, and membrane filtration offer better performance, but challenges remain in handling high salinity, chromium-rich sludge, and overall operational costs. Electrochemical methods offer an efficient and eco-friendly approach to treating highly saline tannery wastewater containing toxic metals, colour, and refractory organics. Techniques like electrocoagulation (EC), electrochemical oxidation (EO), and electro-fenton (EF) remove pollutants effectively with minimal chemical use. Using sacrificial electrodes (Fe, Al) in EC and inert electrodes (graphite, Ti-MMO, BDD) in EO/EF, these systems generate strong oxidants that degrade complex pollutants, reduce sludge, enhance chromium removal, and provide a scalable, energy-efficient solution. Overall, they offer better control and higher efficiency than conventional wastewater treatment methods. In general, the review suggests the potential of innovative electrochemical treatment methods to achieve effective pollutant removal, resource recovery, and sustainable tannery wastewater treatment.