High recovery Reverse osmosis (RO) membrane desalination of inland brackish water sources has been pursued in various regions of the world as a potential approach to generating new water supplies. However, high recovery membrane desalination is often limited by membrane mineral scaling of sparingly soluble mineral salts. Membrane mineral scaling significantly degrades membrane performance with respect to flux and can also damage the membrane. In order to enable scale-free operation, RO process operation in a feed flow reversal (FFR) mode has been recently proposed. In this study, a novel automated Mini, Modular and Mobile (M3) Reverse Osmosis water desalination system was developed to demonstrate membrane performance monitoring in FFR operation using model solutions containing calcium, sodium, sulfate and chloride ions. FFR was triggered by an external scale monitor/ detector (MeMo) connected to the tail element of the M3 RO system while the performance of the lead and tail elements of the M3 system was continuously monitored. The multi-cycle experiments were conducted using a model solution of salinity 2,529 mg/L total dissolved solids, prepared using CaCl2, NaCl, and Na2SO4 mineral salts to yield a feed solution with gypsum (CaSO4•2H2O) saturation index of 0.52. The M3 RO pilot system was utilized to study the operation of the FFR strategy demonstrating effective operation over multiple cycles. Especially since variation of FFR cycles were encountered given the randomness of crystal nucleation on the membrane surface. Accordingly, it is evident that practical application of FFR for mitigating mineral scaling would require both a sensitive scale detection method (such as the MEMO system presented here), as well as automatic feedback control.
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- Han Gu
- University of California Los Angeles (UCLA)
- AMTA Annual Meeting, San Diego, CA
- San Diego Biennial
- Reverse Osmosis, Feed Flow Reversal,