Optimal seawater reverse osmosis network design considering product water boron specifications

• SWRO network design is presented with boron removal levels being considered.
• The performance of different RO element types were investigated using commercial membrane simulators.
• Boron rejection capacities for several membrane types were modeled using data from commercial simulators.
• pH adjustment calculations were enabled, as well as respective acid/base dosing requirements.
• Optimal designs were extracted using compact superstructure representations.

This paper introduces a process synthesis strategy and optimization approach that accounts for boron removal considerations in Seawater Reverse Osmosis (SWRO) network design. The overall aim is to provide an improved understating of the performance of SWRO networks when specific requirements on boron levels in the system need to be met. In theory, this work utilizes the aspects of a well-defined SWRO network synthesis problem that has already been introduced in previous work, and builds on the existing representation by incorporating a number of fundamental aspects that facilitate boron removal in the system. This primarily included the determination of appropriate pH level conditions for the various network streams involved, in addition to the incorporation of a number of RO membrane element choices to be utilized in the system. Therefore, the design options allowed for the integration of a diverse mix of viable RO membrane elements within a single network, rather than strictly relying on one membrane type for all units. This was found necessary since different categories of RO membranes certainly have altered effects on the system’s performance. Efforts directed towards investigating the effects of common operating parameters on boron rejection has been carried out by means of computer-aided membrane simulation tools, in which membrane performance in the form of boron rejection were converted to useful correlations that are then used in the optimization. A case study example involving three different seawater qualities, and correspondingly three different boron levels in each, was carried as a demonstration.