Effect of high salinity on the performance of forward osmosis: Water flux, membrane scaling and removal efficiency

Abstract

In this study, the performance of forward osmosis (FO) in treating the high-salinity feed water was investigated under different temperatures, membrane orientations and flow cross velocities in terms of water flux, membrane scaling and removal efficiency of Ni (II). The results showed that, the enhanced temperature cannot, while the increased cross flow velocity can promote the water flux effectively in treating the high-salinity feed water. The optimal operating conditions were determined to be 35°C and 10cm/s, in which the operation was energy-efficient. The water flux declined gradually with the salinity of feed water. It was more than 10LMH in treating 50g/L NaCl solution, while was 5LMH when the FS salinity increased to 100g/L. The application became unfeasible in the salinity of 100g/L. The membrane scaling was slight in the FO mode; on the contrary, it was severe in the PRO mode and aggravated with the FS salinity. But fortunately, the membrane scaling can be removed effectively by simple physical cleaning. The removal efficiency of Ni(II) in the FO mode was higher than that in the PRO mode, and both of them were higher than 95%. Moreover, the rejection efficiency increased with FS salinity.