ZERO LIQUID DISCHARGE:

Zero liquid discharge means a treatment process in which the plant discharges no liquid effluent into surface waters, in effect completely eliminating the environmental pollution associated with treatment. A ZLD process also makes effective use of wastewater treatment, recycling, thereby contributing to water conservation through reduced intake of fresh water. 

ZLD is a costly process, but it paves the way for economic benefits by recovering salts and other chemical compounds. 

Water scarcity and water economics are the factors driving towards adopting ZLD techniques.

Evaporation, Osmosis, Electrodialysis, distillation are various methods for ZLD.

Some ZLD technologies may result in the recovery of additional water streams alongside the process. Since ZLD systems can be integrated onto interplant water network systems either as central or distributed units, assessing the presence of both scenarios allow for cost-optimal designs to be identified.

Zero liquid discharge (ZLD) is an engineering approach of treating industrial water waste where all water is recovered and contaminants are reduced to solid waste.

ZLD is the most demanding target as environment concern is a big issue.

There are a number of benefits to targeting zero liquid discharge for an industry. Some of the benefits of liquid discharge are as follows:

• Lowered waste volumes decrease the cost associated with waste management.
• Recycle water on site, lowering water acquisition costs and risk. Recycling on-site can also result in less treatment needs, versus treating to meet stringent environmental discharge standards.
• Reduce trucks associated with off-site waste water disposal, and their associated greenhouse gas impact and community road incident risk.