Brackish water desalination is a common method for fresh water supply in arid areas. Concentrated brine is the
major waste stream generated from the desalination process. The current study proposes a multi-stage
Nanofiltration (NF)–Forward Osmosis (FO)–Brackish Water Reverse Osmosis (BWRO) system to increase the
recovery rate of brackish water. The simulation results showed that the NF–FO–BWRO system was able to
achieve N90% recovery rate for a number of feed salinities varied from 1 to 2.4 g/L. High permeability NF membrane
was used in the first stage to produce the first permeate flow at relatively low power consumption. Concentrated
brine from the NF was fed to an FO membrane for power for additional fresh water extraction before
disposal. 0.25–0.5 M NaCl was used as the draw solution in the FO membrane. The results showed that system
recovery rate increased with increasing the concentration of the draw solution. NF process was responsible of
75% of the total recovery rate while BWRO process contribution was up to 20%. Almost 80% of the total power
consumption for desalination was due to the BWRO process. NF and FO processes accounted for the rest 20%
power consumption. The BWRO system also required 2 to 3 times more membranes than FO and NF processes.
NF–FO–BWRO is flexible and can generate different proportions of permeate flows through controlling the recovery
rates of each component.