The presence of calcium sulfate in groundwater limits the degree to which water can be recovered by reverse osmosis. The ZDD (Zero Discharge Desalination) technology removes calcium sulfate as a solid that has potential commercial value. In the ZDD process, RO concentrate is treated by an electrodialysis (ED) process called EDM (electrodialysis metathesis). The CaSO4-depleted solution is returned to the RO feed, and the two concentrated streams are mixed to precipitate CaSO4. NaCl for the EDM can be recovered from the supernatant. When CaSO4 is the main contaminant in the groundwater, the system can approach zero liquid discharge.
This presentation is available to AMTA Members only.
- Thomas Davis, PhD
- University of Texas at El Paso
- AMTA Annual Meeting, Austin, TX
- Pre-Conference Workshop - AMTA/SCMA Membranes for Water Treatment: Federal and State Research Advancements
- reverse osmosis (RO) membrane separation, electrodialysis (ED)