Simultaneous Modeling of Water Purification Process by Direct Osmosis Membrane and Recovery of Osmotic Solution by Ultrafiltration Membrane

In this study, first, the water purification process was modeled by the hybrid of direct osmosis membrane and ultrafiltration, then the current system was compared with experimental results in terms of quality control and costs. In the direct osmosis process, a highly concentrated sodium polyacrylate solution was used as the draw solution. When the FO side of the hybrid membrane met wastewater, seawater, or saltwater, clean water was drawn through the FO membrane into the SPA solution. Then, the clean water was removed from the SPA solution through the UF membrane by applying pressure, which can be hydraulic or mechanical, less than 1 bar. Modeling was done to prove the validity of the design concept. Some model equations were extracted to simulate the performance of the hybrid membrane, and the experimental data were analyzed based on the model equations. It is believed that this method allows the production of RO quality water at a UF pressure much lower than the RO pressure and thus leads to a significant reduction in energy consumption for water production. It was noticed that more water (than the calculated value) could be drawn to the SPA solution when the CSPA,0 was<15.75 wt% while less water was drawn when CSPA,0 was>15.75 wt%.