Using modelling approach to validate a bench scale forward osmosis pre-treatment process for desalination

• Evaluation a batch laboratory-scale FO system as a pre-treatment for the RO process
• FO can help to avoid RO fouling and achieving higher overall water recovery
• Modelling takes into account flux, water recovery and the final draw concentration
• An experimental design methodology has been successfully applied for FO optimisation
• The optimal FO conditions are determined and validated by real brackish water

Forward osmosis (FO) has recently attracted growing attention in wastewater, brackish groundwater and seawater desalination, and power generation. This study evaluates the potential of using a batch laboratory-scale FO system as a pre-treatment for the reverse osmosis (RO) process. FO is a low pressure-driven process that offers many advantages compared to the conventional pre-treatment for RO especially for brackish water with high potential of scaling and fouling. FO can help to reduce the RO process cost by avoiding RO membrane fouling and achieving higher water recovery. An experimental modelling has been employed to describe the FO process taking into account water flux, water recovery and final draw solution. Based on this experimental modelling, the energy consumption for RO has been estimated. It has been found that the treatment time for the FO process and the initial draw solute concentration are important parameters that have an interrelated effect on FO and RO efficiency. The optimal conditions for this FO pre-treatment process are determined by modelling and are experimentally validated by using real brackish water as feed in a bench-scale FO system.