ZLD and Reuse

Zero liquid discharge (ZLD) recovers all of the water from a wastewater stream and leaves only solid salts, so no liquid effluent leaves the site. A typical ZLD plant combines pre-treatment, reverse osmosis, brine concentration by evaporation and a final crystalliser. At Apollo Tyres in Hungary, our 720 m³/day reverse osmosis and LTDis plant recycles almost all of the site's wastewater.

Choose ZLD when regulations demand true zero discharge or water is scarce enough that every cubic metre counts; otherwise MLD often delivers most of the benefit for far less. MLD typically recovers 85–95% of the water and sends a small concentrated stream to disposal, avoiding the most energy-intensive evaporation and crystallisation step. A feasibility study or pilot trial shows which your stream and permit call for.

It depends on whether you have waste heat: if you do, LTDis usually wins on operating cost; if you do not, MVR does. MVR evaporators run on electricity at 8–14 kWh/m³ of evaporated water by recompressing their own vapour, while LTDis runs at 50–80 °C on low-grade heat and handles concentrations through to crystallisation. Many plants combine the two.

Recovered water is often cleaner than the plant's raw water supply, so it can go straight back into production. Depending on polishing, it is reused as process water, cooling-tower or boiler make-up, or ultrapure water for semiconductor and battery production. Reuse cuts both water purchase and discharge costs, and makes energy and power and other industrial sites less dependent on an increasingly scarce supply.

Yes: crystallisation separates salts that can be reused or sold, and the same concentration steps recover valuable metals. That ranges from copper and chrome in surface treatment to lithium and other metals in battery and battery-materials production. At Volta Energy in Tatabánya, separate copper and chrome lines feed LTDis evaporation and crystallisation at 1,024 m³/day.

Yes: we design ZLD and MLD systems for both markets, sized to the local permit and to the value of the water recovered. In India, regulators require zero liquid discharge for a growing range of industries, including textiles, tanneries, distilleries and pharmaceuticals in many states. Across the Gulf, water scarcity makes reuse the cheapest new source of supply, as our chemicals and pharmaceuticals clients know well.