(644a) Optimal Design of Split Partial Second Pass Reverse Osmosis Network for Desalination Applications

Reverse osmosis is a very well established technology for desalination applications. The design problem of reverse osmosis network seeks an optimal configuration of reverse osmosis pressure vessels, pumps and energy recovery units for seawater treatment. The pressure vessel is multiple reverse osmosis modules connected in series. For every pressure vessel, the feed stream is separated into concentrated and permeate streams. In this study, we exploit the reverse osmosis pressure vessel operation by considering detailed variation of stream properties within the pressure vessel itself. This design problem is known as split partial second pass reverse osmosis design concept which allows extraction of high quality permeates from different locations along the reverse osmosis pressure vessel length. Superstructure optimization is adopted to model the reverse osmosis network in order to find: (1) optimal arrangement and operation of the process units, (2) optimal permeate extraction locations from the reverse osmosis pressure vessels, and (3) production of several permeate streams with different qualities. Accase study is presented to show the application of the proposed mathematical programming model. In general, lower treatment cost and higher permeate recovery can be achieved by allowing permeate extraction streams from the reverse osmosis pressure vessels.