Optimization of forward osmosis system for the utilization of reverse osmosis brine

This research aimed to utilize the concentrated brine by incorporating a forward osmosis (FO) system as a post-treatment in a reverse osmosis (RO) plant. The objective of this study was to optimize the operating condition of an FO system utilizing RO brine. Water flux and reverse solute flux were measured at different draw solution (DS) concentrations. Change in the salinity of the feed and permeate flux are the two parameters that were monitored and evaluated. To further optimize the process, membrane fouling was also investigated. Fouled membrane was subjected to scanning electron microscopy and energy dispersive X-ray analyses. Seawater was used as the feed while sodium chloride was used to simulate different brine concentrations. It was observed that increasing the concentration of brine enhances permeate flux. However, increase in reverse solute flux was also observed compensating the high water flux. Fouling in the support layer of FO membrane was evident at 200g/L DS concentration. While 100g/L was found to be the most suitable for FO system with almost similar fouling propensity as compared to 50 and 75g/L. With lower internal concentration polarization and optimized operating condition, FO system could be efficiently used in utilizing RO brine.