Techno-Economic Evaluation of Converting a Tannery CETP into a Zero Liquid Discharge (ZLD) System

Abstract

Tannery wastewater is one of the most challenging industrial effluents to treat due to its high organic load, dissolved solids, and toxic metal content. This study evaluates the performance of the 20 MLD Common Effluent Treatment Plant (CETP) at Uttar Pradesh, which treats effluent generated from the local leather cluster. The plant incorporates a multi-stage treatment system comprising primary, secondary, and tertiary units, designed to ensure compliance with environmental discharge norms. Influent and effluent samples were collected from critical treatment points and analyzed for key physicochemical parameters including pH, COD, BOD, TSS, TDS, and chromium. The results indicate that the CETP effectively reduces about 90– 94% of COD, 85–90% of BOD, and over 95% of TSS through successive stages of coagulation, biological oxidation, and filtration. While pH and suspended solids remain within permissible limits, the final TDS levels exceed discharge standards, highlighting the need for advanced tertiary measures such as reverse osmosis or zero liquid discharge (ZLD) systems. The study concludes that the 20 MLD CETP demonstrates stable and efficient operation, substantially improving tannery wastewater quality and offering a replicable model for sustainable industrial effluent management.