Evonik Catalysts (Essen, Germany; www.evonik.com) has opened a new Zero Liquid Discharge (ZLD) plant at its facility in Dombivli, India. The new plant reduces the amount of freshwater required for production processes and turns material that was previously considered waste into saleable products.
ZLD purifies and recycles wastewater at the end of an industrial process, leaving little to no effluent remaining when it is completed. This means not only more efficient water use but also a significant reduction in the waste liquid.
Evonik is developing site-specific action plans as part of its global water management system. One focus is on sites in regions that could be affected by water scarcity. It also strives for the most efficient use of water.
The main ambition of the Dombivli ZLD plant is to improve the treatment of process water. It goes through a multi-stage process and then the byproducts go through further processing. An estimated 600 m3 of wastewater – the equivalent of between 25 and 30 tankers – enters the ZLD plant every day and the plant is expected to recirculate around 55 percent of that – approximately 300-350 m3 – for process reuse and the balance water for re-use as cooling tower make up thus reducing Evonik water use requirements and thereby reducing Evonik’s dependence on municipal water supplies.
The requirement for freshwater will be reduced by 65 percent after stable operation of zero liquid discharge and the company is targeting further reductions through process optimization.
In addition, processing leads to the production of 15-20 metric tons of sodium sulfate and certain mixed salts, which can be resold as a commercial product
The ZLD plant is set up on a ‘BOOT’ Model between Evonik and Remondis, with the latter responsible for building, owning, operating, maintaining, and transferring the ZLD plant to Evonik.