Reverse osmosis (RO) and pressure retarded osmosis (PRO) hybrid processes: Model-based scenario study

• Published in: Desalination 2013-08, Vol.322, p.121-130
• Main Authors: Kim, Jihye, Park, Minkyu, Snyder, Shane A., Kim, Joon Ha
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical engineering; Cost analysis; desalination; energy; Exact sciences and technology; Membrane separation (reverse osmosis, dialysis...); Natural water pollution; Pollution; Pressure-retarded osmosis (PRO); prices; reverse osmosis; Reverse osmosis (RO); RO–PRO hybrid system; seawater; Seawaters, estuaries; Water and energy return rate (WERR); Water treatment and pollution
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2013.05.010

We conducted a scenario study on a promising RO–PRO hybrid system to alleviate water and energy demands. We utilized a previously validated reverse osmosis (RO) process model and modified a model of a pressure-retarded osmosis (PRO) process to properly consider the spatial distribution of concentration and velocity based on a mass balance principle. Using the models, we compared four different RO–PRO hybrid configurations based on the water and energy return rate (WERR). Subsequently, the comparison of the water production rate and energy production rate confirmed the results that RO plays a dominant role to determine the WERR value. Hybrid systems that use seawater as a feed water for RO are more energy price sensitive. That is, a decrease in the RO plant size considerably diminishes the WERR values; however, the PRO plant size plays a minor role to determine the WERR value. Research and available literature on RO–PRO hybrid processes are in a relatively early stage; this study is a preliminary step to evaluate further advances in hybrid systems that can eventually alleviate water and energy demands. •A model-based scenario study assessed the RO–PRO hybrid processes.•A cost analysis evaluated RO–PRO hybrid systems.•RO plays a crucial role to determine water and energy production (WERR).•PRO plant size plays a minor role to determine WERR value.•The use of RO as PRO draw solution is beneficial to augment power generation.