Recovery of Fresh Water from Industrial Effluents by Forward Osmosis

Full Name: Georgios Kolliopoulos

Academic Affiliation: University of Toronto

Position: PhD candidate

Abstract: One of the most important commodities of our era is water. The chemical and the mining industry use aqueous solutions to a high extent in their production lines, and subsequently discharge large volumes of effluent streams. Sustainable development suggests that the water used in these processes should be recovered and recycled to minimize fresh water intakes. To date, the technologies used to recover water (distillation, or membrane processes, such as RO: Reverse Osmosis) are energy intensive, and often limited to effluent streams with less than sea-like water concentration. Osmosis is the phenomenon that describes the movement of water molecules from a dilute to a concentrated solution through a semi-permeable membrane that selectively allows this passage. Forward Osmosis (FO) is a new process, able to recover water from more concentrated streams with less energy. It relies on the concentration difference (driving force) between the effluent and an engineered concentrated “draw solution” (CDS). Water molecules move to the spontaneous direction and are recovered in the CDS, which eventually gets diluted. The dilute draw solution (DDS) is then thermally treated to recover fresh water and regenerate the CDS, which is recycled in the FO process. The energy requirements mainly arise from the separation of fresh water from the CDS, and the subsequent regeneration of the latter. The CDS is designed in such way, that can be fully separated from water at temperatures well-below 100 C. The effectiveness of the very promising FO process is evaluated to allow the design of an energy efficient way to recover water from industrial effluents.