Synergistic solutions: reverse osmosis and nanofiltration configurations for efficient brackish water desalination

Pilot testing using feed water sourced from the Yuma Desalting Plant (~2 g/L) (Arizona, USA), an inland brackish water desalination facility, was conducted using either tight Dupont Filmtec Nanofiltration (NF) NF90 membranes or looser NF270 membranes as integrated, pre-treatment, or brine recovery for Reverse Osmosis (RO). The hybrid configurations that include both NF270 and RO membranes exhibited the highest RO water flux, 37– 41 Lm⁻² h⁻¹, with over 99% salt rejection. However, the cost was strongly influenced by the volume of brine produced compared to the energy consumption, resulting in the lowest cost in the NF270 brine recovery configuration. Both the pilot study and modeling data indicate that NF270 and RO membrane hybrid configurations are an economically viable treatment for water purification in inland areas where brackish water is a prevalent water source.