Pressure retarded osmosis for energy production: membrane materials and operating conditions

2012 ◽  
Vol 65 (10) ◽  
pp. 1789-1794 ◽  
Author(s):  
H. Kim ◽  
J.-S. Choi ◽  
S. Lee
Keyword(s):  
Energy Production ◽  
Concentration Polarization ◽  
Forward Osmosis ◽  
Operating Conditions ◽  
Polarization Ratio ◽  
Pressure Retarded Osmosis ◽  
Fundamental Understanding ◽  
Internal Concentration ◽  
Membrane Type ◽  
Osmotic Pressure Difference

Pressure retarded osmosis (PRO) is a novel membrane process to produce energy. PRO has the potential to convert the osmotic pressure difference between fresh water (i.e. river water) and seawater to electricity. Moreover, it can recover energy from highly concentrated brine in seawater desalination. Nevertheless, relatively little research has been undertaken for fundamental understanding of the PRO process. In this study, the characteristics of the PRO process were examined using a proof-of-concept device. Forward osmosis (FO), reverse osmosis (RO), and nanofiltration (NF) membranes were compared in terms of flux rate and concentration polarization ratio. The results indicated that the theoretical energy production by PRO depends on the membrane type as well as operating conditions (i.e. back pressure). The FO membrane had the highest energy efficiency while the NF membrane had the lowest efficiency. However, the energy production rate was low due to high internal concentration polarization (ICP) in the PRO membrane. This finding suggests that the control of the ICP is essential for practical application of PRO for energy production.

Concentration Enrichment of Fermentation Derived Acetic Acid: Transport Modeling of Forward Osmosis-Nanofiltration Integrated System

2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Jayato Nayak ◽  
Parimal Pal ◽  
Zunipa Roy ◽  
Sankha Chakrabortty ◽  
Pinaki Dey ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Concentration Polarization ◽  
Transport Model ◽  
Acid Output ◽  
Forward Osmosis ◽  
Integrated System ◽  
High Concentration ◽  
Excellent Performance ◽  
Production Scheme ◽  
Internal Concentration

Abstract Forward Osmosis (FO)-Nanofiltration (NF) integration as the final product polishing step enables high concentration of acetic acid output through continuous dehydration of fermentation derived product. A mathematical transport model has been developed based on external and internal concentration polarization modulus of FO and extended Nernst–Plank equation for NF to capture the flux and rejection trends from those membranes. The modular designed production scheme ensured high flux (45 Lm−2 h−1), concentration (962 g L−1) and purity (>98 %) of acetic acid under non-neutralization condition. Excellent performance of the model is reflected in low relative error (<0.05), high Willmott d-index (>0.97) and high correlation coefficient (>0.98).

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