Question

Prepare a short report that technically and economically evaluates the differences between ZLD (zero-liquid-discharge) and MLD (minimum-liquid discharge) methods, which are also application areas in desalination facilities.

Answer 1

Zero liquid discharge (ZLD) is a water treatment process in which water is treated and recycled after leaving zero liquid discharge from the water treatment cycle, but to the additional material in the process , more energy and disposal resources are required which causes technical intimadating and for that it is highly expensive and not environmental friendly.

Where, Minimum liquid discharge (MLD) is also the water treatment process in which water is treated and recycle after leaving 95% liquid discharge from the water treatment cycle at ZLD's cost. In this process water is treated by ultrafiltration, nanofiltration, River osmosis which are typically environmental friendly and more cost effective.

In heavy plant, cooling tower blowdown, municipal potable water systems, small scale industry etc in those several places MLD is preffrred for desalination of water due to get more recovery of solid discharge in less cost.