Sodium chloride recovery from brines for reuse purposes in zero liquid discharge

In the application of the Zero Liquid Discharge (ZLD) strategy, not a single drop of water leaves the waste water treatment plant (WWTP). In the recovery strategy of an actual full-scale ZLD WWTP, the focus lies on high quality water, which is fully recovered from reverse osmosis brine (RO-brine). A residual solid stream is generated and consists of mixed solids. The bulk of these solids is sodium chloride (NaCl), which has great potential to be reused when it is of high purity. Additional constituents, exceeding the quality restriction limits, are considered as contaminants. This research focussed on the isolation of dissolved NaCl from contaminants in the RO-brine, in order to finally recover high purity NaCl. To this extend, nanofiltration, electrodialysis and ion exchange were tested to their potential to isolate dissolved NaCl. Additionally, a solid purification technique was tested as an alternative to produce high purity NaCl.Sanitary EngineeringWater ManagementCivil Engineering and Geoscience