Zero liquid discharge (ZLD) means no wastewater leaves your factory. For textile and leather units, that solves the water problem but creates a salt problem. The plant leaves a wet, coloured mix of salts every day. You cannot sell it and you cannot dump it, so it piles up in a hazardous waste yard month after month.
Separate the salts and reuse them
Dyeing and leather work use a lot of common salt and Glauber's salt (sodium sulphate). A step-by-step separation brings each salt out on its own, clean. At that purity both salts can go back into the dye house or be sold.
Get the solvent back before it reaches the ETP
Pharma and fibre factories often lose costly solvents into their wastewater, then pay again to treat it. Solvent recovery takes the solvent back out so it can be used again. Every litre you recover is a litre your ETP does not have to clean.
Metals and minerals are worth money too
- Metal sludge and used catalysts: turn them into pure metals or battery materials.
- Salty steel plant water: remove most of the salt so the water can be reused without rusting pipes.
- Distillery ash: make potash fertiliser from it.
- Aluminium waste: make alum for your own ETP.
Plan for it from day one
Getting salt back works best when each type of wastewater is kept in its own pipe. If very salty water is mixed with lightly salty wash water, the salts are harder to separate and the plant has to be bigger. Keeping the streams apart is the cheapest step in any ZLD project.
Planning or fixing a ZLD plant?
We map your wastewater streams, test them in our lab and plan salt recovery from the start. See the full list in our technology showcase.
Request a consultationFrequently asked questions
Can recovered Glauber's salt be used again for dyeing?
Yes, if it is clean enough for your dye house. Salt recovered at over 98.5% purity suits most dyeing work.
Does getting salt back lower ZLD costs?
Yes. You store less hazardous waste and buy less salt. Keeping wastewater streams apart can also make the ZLD plant smaller.
Where should I start?
Test each wastewater stream separately for salts, pollution and colour. What you can recover depends on those results.
Sources: Water Channel: national ZLD guidelines for industrial clusters. The results above come from real use of each method. Your results depend on your water, so test it first.
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