A Perspective from India on Treated Wastewater Reuse: Few Case Studies

In Indian industries, the wastewater reclaim-reuse-recycle practice has been prevalent since the last two decades due to acute water shortage as well as high cost of freshwater supply. This paper presents case studies of water reclamation projects in the textiles processing, automobiles, chemicals, and fertilizers industries, and the municipal sector where the author was involved. Reclamation requires affordable wastewater treatment and its hazard free sustained reuse. The Indian Reuse and Discharge Standards were revised upwards in April/May 2018 by the National Green Tribunal for the whole country with wide implications on the choice of treatment strategies, processes, and technology. This paper showcases the water reclamation plants in India. A 15 MLD textile processing ETP of Trident Group reclaims 10 MLD water, a 23 MLD STP of RCF Trombay recycles 16 MLD water; another 1.5 MLD auto industry ETP of Mahindra & Mahindra at Nashik recycles the whole quantity for non-potable reuse. The process and design engineers had to develop robust, consistent, and cost-effective process regimes including advanced bio-oxidation and membrane based processes like ultrafiltration and reverse osmosis followed by UV for disinfection. The wastewater characterization, selection of technology, and design of process units and project realization for water reclamation was a very rewarding experience. A few water reclamation cases from India are presented to showcase the successful management of challenges of water scarcity.