Zero Liquid Discharge (ZLD) is a procedure for the treatment of wastewater. Through this process, wastewater is treated and recycled to make it fit for reuse. ZLD has been named as such because it ensures zero discharge at the end.
A brief about ZLD
ZLD is an advanced treatment process that is employed for effluent generated during industrial production which is contaminated with several organic and inorganic pollutants. It is a multi-step, detailed procedure that transforms hazardous effluents into water that’s safe for use in industries and landscape irrigation.
Because of the kind of water being treated, ZLD involves multiple compliances, strict regulations, and other considerations. All these, put together, make it quite an expensive process.
Benefits of ZLD
Despite being complex and expensive, Zero Liquid Discharge is becoming increasingly popular because of the benefits it offers. A few are as follows:
- There’s no wastewater discharge because of the recycling process
- It helps recover salt and water, reducing overall wastewater management costs
- It directly helps the environment by lowering pollution and saving water
- The sludge gathered from the treatment sees applications in the cement industry
The most significant benefit is, of course, its contribution to the environment. This serves as the biggest motivator to continue investing in ZLD technology.
The technologies used in ZLD
As is already evident, ZLD is very complicated. It involves the use of multiple technologies and membranes based system, including the following:
- Sedimentation: This is the process of removing sediments and coarse particles from the water
- Dissolved air flotation: Immediately after sedimentation, the wastewater goes through dissolved air flotation, which removes dispersed particles, oils and colloids.
- Biological treatment: This step removes organic containments in effluent with help of microbes.
- Filtration system- Removes suspended solid, colloids
- Ultrafiltration: These membranes remove bigger dissolved organic material and other impurities. Here, residual solids, organic matter, colloids, bacteria, viruses, etc. are effectively removed.
- RO: This is the final step of membrane technology that ensures that all impurities are removed, including metals and dissolved solids before water is recycled.
- Brine Concentrator- Advance water recovery process, which minimizes the reject going to final most expensive step of evaporation.
- Evaporator- Evaporation process is the final step for ZLD for management of reject, which converts all dissolved salt in to powder and condensate recovered gets recycled back to the process.
Only after going through each step and final testing is the water passed for reuse.
Wastewater treatment at Permionics
Permionics has pioneered ZLD technologies with its revolutionary, sustainable concept that directly treats effluent using membrane technology after advanced pre-treatment. The system is being used in the Biotech & Pharma, Distillery, Sugar, Textile, PCD Manufacturing, Dairy, Vegetable Oil Manufacturing, Dyeing & other industries. The staged systems have consistently been able to recover at least 90% of the wastewater depending on feed water characteristics.
This membrane system, along with Permionics’ advanced Brine Concentrator, is contributing immensely towards sustainability.
