Effects of working temperature on separation performance, membrane scaling and cleaning in forward osmosis desalination

Recently forward osmosis (FO) has drawn increasing attention in wastewater treatment, brackish water/seawater desalination and power generation. It is supposed that FO has many advantages over other pressure-driven processes, such as low energy consumption, low fouling tendency, high water recovery and thus minimizing brine volume. In FO process, many parameters like osmotic pressure, fluid viscosity, mass transfer and mineral solubility are temperature dependent. In the current study, the effects of working temperature on separation performance (e.g. water fluxes and recoveries), membrane scaling and cleaning were systematically investigated through a bench-scale FO system. Both real and simulated brackish water were used as the feed solution in FO at temperatures of 25, 35 and 45 °C. Bench-scale FO experiments showed that higher temperature would afford higher initial fluxes, higher water recoveries and higher concentration factors, but also caused more adverse effects on membrane scaling and cleaning.

► Forward osmosis was used for bench scale brackish water desalination experiment.
► Effects of temperature on separation performance, membrane scaling and cleaning were studied.
► Higher temperature resulted in higher initial fluxes and higher water recoveries.
► More adverse effects on membrane scaling and cleaning were also caused at higher temperature.