Zero liquid discharge (ZLD) is a treatment approach in which a factory recovers and reuses almost all of its wastewater, leaving only solid residue behind. With groundwater levels falling in industrial areas, interest in ZLD is growing.
How ZLD works
A ZLD system builds on a conventional ETP:
- Biological and chemical treatment remove most pollutants
- Ultrafiltration and reverse osmosis recover clean water for reuse
- The concentrated reject is evaporated, leaving salts as a solid
The benefits
- Large reductions in groundwater extraction
- A reliable water supply for the process
- A strong position with international buyers that set water targets
The challenges
ZLD systems cost more to build and run, mainly because of the energy needed for evaporation. They also need skilled operators and careful handling of the solid residue.
A step-by-step path
Many factories start with partial recycling — reusing treated water for washing, cooling or toilets — before moving towards full ZLD. An audit of water use often reveals easy savings first.
We assess water use, design recycling systems and help factories plan a realistic route towards zero liquid discharge.
- #ZLD
- #Water reuse
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