Evaluation of Salt-Free Electrodialysis Metathesis for High Recovery Reverse Osmosis Concentrate Management

Evaluation of Salt-Free Electrodialysis for High Recovery Reverse Osmosis Concentrate Management Tayia Oddonetto, March 2024, 3: PM The “Gold Standard” of Desalination Pressure driven process Accounts for 2/3 of total market share Typically limited to a recovery of 75-85% Terminology AEM: Anion Exchange Membrane CEM: Cation Exchange Membrane mAEM: Monovalent Anion Exchange Membrane mCEM: Monovalent Cation Exchange Membrane Diluate: Diluting stream Conventional Electrodialysis Metathesis (EDM) Keeps Ca2+ and SO 2- separate! 4 Conventional Salt-Free Electrodialysis Electrodialysis Electrodialysis Metathesis Metathesis Cell Pairs Cell Quads Cell Quads (monovalent selective membranes) One Concentrate Two Concentrate Stream Streams (Mixed Na+, Two Concentrate mixed Cl-) Streams (SO 2- , Ca2+ rich) 4 No Additional Chemicals Aqueous NaCl No NaCl Necessary Solution Critical Parameters for Evaluation Removal Ratio Specific Energy Consumption (R) (SEC) Current Density as a Function of Removal Run Run Run Current density 150 decreases as removal increases Fewer ions available to transport charge 50 0.0 0.5 1.0 )2m/A( ytisneD tnerruC Removal Ratio (-) Final Remarks Salt-free EDM is simpler than conventional EDM Conventional EDM required 400 lbs of salt added per day! Improving Desalination Recovery Using Zero Discharge Desalination (ZDD): A Process Model for Evaluating Technical Feasibility. Mathematical modeling of a modular convectionenhanced evaporation system. F., Chosa, M., Bhalekar, P., & Wright, N.