Scientific Achievement
Identifies a hybrid electrodialysis (ED)-Nanofiltration (NF)/reverse osmosis (RO) system and identifies appropriate properties of ion exchange membranes of ED pretreatment for water sources that require little or no desalination but have high NOM concentrations.
Image: Schematic of a hybrid ED-NF/RO system: ED would create two streams: diluate and concentrate. The ED diluate would then pass through the NF/RO process to remove NOM. Finally, the NF/RO permeate and the ED concentrate would be recombined, forming a product water that would have close to the original inorganic concentration but much lower NOM concentration.
Significance and Impact
Provides insight not only into the ideal properties for membrane selection or fabrication for ED pretreatment prior to NF or RO membrane filtration but also for other ED treatment applications that target removal of solutes sensitive to the presence of NOM.
Research Details
- This research focused on ion and NOM separation with ED.
- The results indicate that ED can effectively separate alkaline earth metal ions without separation of NOM .
- Cation exchange membranes with high exchange capacity, high selectivity for divalent cations are desirable, and both anion and cation exchange membranes should have low affinity for organic adsorption.
Soyoon Kum, Desmond F. Lawler, Lynn E. Katz, Separation and Purification Technology (2020).
Work was performed at The University of Texas at Austin.