Zero liquid discharge can be defined broadly as a process for maximum recovery of water from a wastewater source that would otherwise be discharged. This water is beneficially reused and the salts, and other solids contained in the waste water are produced and generally disposed in a landfill.

Zero liquid discharge can be achieved in various ways. There is no “one size fits all” solution, as the optimal system design is site specific. The wastewater composition, various streams to be treated, site specific operating costs, foot print availability and other factors are determining factors for an optimal design.

Zero liquid discharge system are to eliminate a liquid waste water discharge, generate solids for landfill disposal or reuse, and to recycle a high-quality water that can be beneficially reused.

It is prediction that process water will become an increasingly scarce resource. This means that so much water is extracted from the ecosystems, that there will be insufficient left to sustain them. With the increase of the world’s population, the demand for food grows in proportion, increasing the water demand for irrigation and production processes even more. The industry is seen as a major consumer and will be forced to take measures to reduce water consumption. Industries that consume large volumes of water or discharge highly toxic effluent are candidates to employ membrane technologies for water reuse.

Ultrafiltration and Reverse Osmosis Techniques are normally opted. Ultrafiltration is used to recycle flow or add value to later products and more. In many cases ultrafiltration (UF) is used for prefiltration in reverse-osmosis plants to protect the reverse-osmosis process. Ultrafiltration is an effective means of reducing the silt density index of water and removing particulates that can foul reverse osmosis membranes.