2025 AIChE Annual Meeting

(300d) Bwro Brine Treatment Using Hybrid Monovalent Selective ED (MSED) Low Salt Rejection RO (LSRRO)

Authors

Jack Gilron - Presenter, Ben Gurion University of the Negev
Menachem Elimelech, Yale University
Tzahi Cath, Colorado School of Mines
The limitation of recovery in brackish water RO is predominantly hampered by precipitation of sparingly soluble salts such as calcium salts and silica, but at extremely high recoveries associated with near ZLD, it can also be limited by osmotic pressures. By coupling monovalent cation selective ED (MSED)1,2 with Low salt rejection RO (LSRRO)3 to treat the ED concentrate, the BWRO can achieve very high recoveries (>99%) with a brine that can reach 10-20% TDS.4 The ED diluate can then be recombined with the main BWRO permeate, thereby supplying needed hardness for drinking and irrigation purposes.

We present here the initial piloting results using MSED to treat BWRO concentrate with innovations for increased capacity and recovery.

For small capacity LSRRO there is a hydraulic challenge arising from the very low flow rates generated of the highly concentrated brines that result in flow rates which can be below manufacturers specifications for module operation. We have proposed to use a series of stages with internal recycling to overcome this issue4 and will present a design with process simulation and preliminary results of a pilot unit incorporating this design. By using the stages based on the flexible RO (FLERO) system design,5 we can also incorporate energy recovery from the recycled concentrates and provide process flexibility that can accommodate modules with varying salt rejections.

REFERENCES:

  1. Cohen B, Lazarovitch N, Gilron J. Upgrading groundwater for irrigation using monovalent selective electrodialysis. Desalination. 2018;431:126-139. doi:10.1016/j.desal.2017.10.030
  2. Ahdab YD, Rehman D, Schu G, Barbosa M, Lienhard JH. Treating Irrigation Water Using High-Performance Membranes for Monovalent Selective Electrodialysis. doi:10.1021/acsestwater.0c00012, EST Water. 2021; 1: 117-124.
  3. Du Y, Wang Z, Cooper NJ, Gilron J, Elimelech M. Module-scale analysis of low-salt-rejection reverse osmosis: Design guidelines and system performance. Water Res. 2022;209. doi:10.1016/j.watres.2021.117936
  4. Gilron, J., Elimelech, M., Cath, T, Reverse Osmosis Systems and Methods, US 2024/0359138 A1.
  5. Lee, T., Rahadianto, A., Cohen, Y., Flexible Reverse Osmosis (FLERO) Desalination, Des. v. 452 (2019), 123-131.