Application of forward osmosis membrane technology in nutrient recovery and water reuse

In recent years, global fertilizer demand has been rising quickly and resource supply may be depleted by the end of the 21st century. Hence, a number of physicochemical and biological processes have been implemented to recover nutrients from wastewater and sludge; nevertheless, these processes consume more chemicals and energy, leading to the emission of greenhouse gases. Meanwhile, forward osmosis (FO)-based technology has been largely discovered to simultaneously recover water and enrich nutrients from wastewater with low membrane fouling and low energy consumption. In hybrid FO-based systems, the FO membrane is used to concentrate nutrients from wastewater while chemical precipitation is encouraged for recovering nutrients in the form of struvite or other membrane technologies used to separate a diluted draw solution. However, this technology still has some limitations, such as concentration polarization, membrane fouling in long-term FO operation, high reverse salt flux from the draw solution, which need to be handled before making it more practical. This book chapter focuses on the mechanism of the FO process, the key factors affecting the FO performance, the recent advanced hybrid FO-based system for nutrient recovery and water reuse, and future research directions.