Energy and resource recovery from tannery wastewater for sustainable leather production

The tanning industry, while economically significant, generates substantial volumes of complex wastewater containing organic matter, salts, sulfides, dyes, and heavy metals, particularly chromium. Conventional treatment approaches, primarily designed as end-of-pipe solutions, face increasing challenges due to their limited capacity to address environmental, energy, and sustainability concerns. In recent years, resource recovery and energy generation from tannery waste streams have emerged as promising strategies aligned with circular economy principles. Previous reviews have cataloged treatment options but often lack a critical, comparative analysis of the techno-economic viability of integrated energy and resource recovery pathways. This review evaluates the performance and economic feasibility of anaerobic and electrochemical systems for energy recovery, alongside advanced separation processes for reclaiming chromium, proteins, and water. Quantitative data on biogas yields, energy recovery efficiencies, and resource reclamation pathways are presented. Global case studies are analyzed to highlight opportunities and barriers. The paper concludes that integrated systems for pollution control and resource valorization represent a transformative approach to sustainable leather production.