A conceptual design of low fouling and high recovery FO–MSF desalination plant

Abstract

Forward Osmosis (FO) has many applications in water and wastewater treatment and seawater desalination. In this paper, the FO was suggested for seawater pretreatment to the thermal desalination processes such as Multi Stage Flashing (MSF). The integrated FO–MSF hybrid system was designed to reduce the cost of desalination in which the brine reject from MSF was recycled and reused as a draw solution in the FO process. A simple model was suggested here to estimate water flux and power consumption in the FO process and compared with Nanofiltration (NF) process which was previously used in seawater softening. The simulation results showed that for feed salinities between 32,000mg/L and 50,000mg/L the recovery rate in the NF was higher than that in the FO. It is also found that the water permeability and specific power consumption was higher in the NF than that in the FO. However, power consumption in the FO wasn't affected by the feed salinity while it increased with feed salinity in NF. Therefore, the FO process has the potential to replace the NF seawater pretreatment for thermal desalination.