Modeling Forward Osmosis Processes

Forward osmosis (FO) has emerged as an alternative membrane process to the conventional pressure-driven membrane processes in recent years. This presentation attempts to discuss the modeling of FO processes in a systematic manner. A mechanistic internal concentration polarization (ICP) model, which accounts for the various driving force loss mechanisms, is first derived based on solution-diffusion in the FO rejection layer and diffusion-convection in the FO support layer. The ICP model is able to predict water flux as well as solute flux well. This model is further extended to model various FO based processes, such as the solute accumulation phenomenon in the FO membrane bioreactor (OMBR). The implications on the FO membrane design and process operation will be discussed.