Integration and optimization of pressure retarded osmosis with reverse osmosis for power generation and high efficiency desalination. (15th May 2016)

• Record Type: Journal Article
• Authors: Altaee, Ali; Millar, Graeme J.; Zaragoza, Guillermo
• Is Part Of: Energy. Volume 103(2016)
• Page Start: 110
• Page End: 118
• Publication Date: 2016-05-15
• Subjects: Salinity gradient power -- Pressure retarded osmosis -- Reverse osmosis -- High recovery desalination -- Brine valorisation; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2016.02.116
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: Salinity gradient power is proposed as a source of renewable energy when two solutions of different salinity are mixed. In particular, Pressure Retarded Osmosis (PRO) coupled with a Reverse Osmosis process (RO) has been previously suggested for power generation, using RO brine as the draw solution. However, integration of PRO with RO may have further value for increasing the extent of water recovery in a desalination process. Consequently, this study was designed to model the impact of various system parameters to better understand how to design and operate practical PRO-RO units. The impact of feed salinity and recovery rate for the RO process on the concentration of draw solution, feed pressure, and membrane area of the PRO process was evaluated. The PRO system was designed to operate at maximum power density of Δ P = Δ π 2 . Model results showed that the PRO power density generated intensified with increasing seawater salinity and RO recovery rate. For an RO process operating at 52% recovery rate and 35 g/L feed salinity, a maximum power density of 24 W/m 2 was achieved using 4.5 M NaCl draw solution. When seawater salinity increased to 45 g/L and the RO recovery rate was 46%, the PRO power density increased to 28 W/m 2 using 5 M NaCl draw solution. The PRO system was able to increase the recovery rate of the RO by up to 18% depending on seawater salinity and RO recovery rate. This result suggested a potential advantage of coupling PRO process with RO system to increase the recovery rate of the desalination process and reduce brine discharge. Highlights: PRO process is integrated with RO and design for salinity gradient power plant. PRO process is optimized to reduce the operation and capital costs. RO brine is used as the feed solution of the PRO process. Integration of PRO with RO reduces power consumption of desalination process. RO recovery rate is increased after coupling with PRO process.