Forward Osmosis: Potential Use In Desalination and Water Reuse

There has been a recurring interest in using Forward Osmosis (FO) process in water treatment and desalination. The recent advance in membrane technology has encouraged further investment in the process technology. Despite the promising results from pilot and bench scale experiments the technology is still not commercialized yet. Obviously, this is due to the complicated nature of the process which usually involves multiple stages of treatment in addition to the FO membrane process. Unfortunately, most of the recent studies were focused on studying the FO process alone and didn’t provide enough data about the actual cost of the process which includes the osmotic agent regeneration stage/s. This issue resulted in some uncertainties about the total cost of the water treatment by the process. Furthermore, more data are required to evaluate the impact of the osmotic agent losses on the overall cost and efficiency. Same concern should be focused on the effect of salt diffusion from seawater to the draw solution on the quality of the product water. This is particularly important due to the salt accumulation in the system when the draw solution is recycled and reused. In case if the draw solution is regenerated by membrane treatment, a suitable membrane should be selected to ensure an optimal salt rejection. For power generation by Pressure Retarded Osmosis (PRO) process, there was an evident progress. However, the process is site specific; i.e. it is dependent of the availability of the draw and donor solution. This suggested that the process is applicable to certain areas but can’t be generalized. A quick review on the FO processes applications in water treatment and power generation is covered here to assess its potential use based on the recent development that have been made so far.