Utilizing Hybrid RO-OARO Systems as New Methods for Desalination Process





hybrid, reverse osmosis, osmotically assisted reverse osmosis, desalination


The scarcity of fresh water and its essential role in sustaining life on Earth have motivated researchers to seek new, low-cost, scalable technologies for water desalination. Therefore, the osmotically assisted reverse osmosis (OARO) membrane process presents an innovative approach to achieve moderate water recoveries from high salinity water without undergoing a phase change. This work aims to investigate the performance of hybrid RO-OARO systems with various designs and operational parameters on recovery and R%. The hybrid systems were evaluated for 60 minutes at feed concentrations of 3.98-5.54 g/l, applied pressures ranging from 3 to 7 bars, and different membrane types. The results showed that the flux of the hybrid system increased by increasing the pressure and decreased by increasing the feed concentration. The highest recovery value was obtained for the RO-OARO system at an RO pressure of 7 bar and an OARO unit at 3 bar for a 3.98 g/l feed concentration. In contrast, when the reverse osmosis pressure was fixed at 5 bar, and the pressure of the OARO unit increased by 2 bar, the recovery value exceeded by about 6%. Furthermore, the FilmTech membrane showed the highest recovery at 31.7%, while the highest R% was 94.55% for the AquaTec membrane. The RO-OARO-OARO system contributed to increasing both the recovery and rejection values by 11.4 and 2.1%, respectively, compared with the RO-OARO system. The experiments in this study revealed a slight increase in the feed concentration of the reverse osmosis unit, indicating the efficiency of the hybrid systems compared to traditional RO systems.


A. F. Al-Alawy and R. M. Al-Alawy, “Thermal Osmosis of Mixtures of Water and Organic Compounds through Different Membranes,” Iraqi Journal of Chemical and Petroleum Engineering, vol. 17, no. 2 SE-Articles, pp. 53–68, Jun. 2016, https://doi.org/10.31699/IJCPE.2016.2.7

A. F. Al-Alawy and M. H. Salih, “Experimental Study and Mathematical Modelling of Zinc Removal by Reverse Osmosis Membranes,” Iraqi Journal of Chemical and Petroleum Engineering, vol. 17, no. 3, pp. 57–73, 2016, https://doi.org/10.31699/IJCPE.2016.3.5

F. A. Yaseen, A. F. Al-Alalawy, and A. Sharif, “Renewable energy by closed-loop pressure retarded osmosis using hollow fiber module,” AIP Conference Proceedings, vol. 2213, no. 1, p. 20201, Mar. 2020, https://doi.org/10.1063/5.0000156

R. M. Kadhim, E. E. Al-Abodi, and A. F. Al-Alawy, “Citrate-coated magnetite nanoparticles as osmotic agent in a forward osmosis process,” Desalination and Water Treatment, vol. 115, no. January, pp. 45–52, 2018, https://doi.org/10.5004/dwt.2018.22456

A. Alkaisi, R. Mossad, and A. Sharifian-Barforoush, “A Review of the Water Desalination Systems Integrated with Renewable Energy,” in Energy Procedia, vol. 110, pp. 268–274, 2017, https://doi.org/10.1016/j.egypro.2017.03.138

B. Al-Najar, C. D. Peters, H. Albuflasa, and N. P. Hankins, “Pressure and osmotically driven membrane processes: A review of the benefits and production of nano-enhanced membranes for desalination,” Desalination, vol. 479. Elsevier B.V., Apr. 01, 2020, https://doi.org/10.1016/j.desal.2020.114323

J. R. Du, X. Zhang, X. Feng, Y. Wu, F. Cheng, and M. E. A. Ali, “Desalination of high salinity brackish water by an NF-RO hybrid system,” Desalination, vol. 491, p. 114445, Oct. 2020, https://doi.org/10.1016/J.DESAL.2020.114445

M. H. Salih and A. F. Al-Alawy, “Crystallization Process as a Final Part of Zero Liquid Discharge System for Treatment of East Baghdad Oilfield Produced Water,” Iraqi Journal of Chemical and Petroleum Engineering, vol. 23, no. 1 SE-Articles, pp. 15–22, Mar. 2022, https://doi.org/10.31699/IJCPE.2022.1.3

M. C. Garg, “Renewable energy-powered membrane technology: Cost analysis and energy consumption,” in Current Trends and Future Developments on (Bio-) Membranes: Renewable Energy Integrated with Membrane Operations, Elsevier, 2019, pp. 85–110, https://doi.org/10.1016/B978-0-12-813545-7.00004-0

A. Alkhudhiri, N. Darwish, and N. Hilal, “Membrane distillation: A comprehensive review,” Desalination, vol. 287. pp. 2–18, 2012, https://doi.org/10.1016/j.desal.2011.08.027

S. Liyanaarachchi, L. Shu, S. Muthukumaran, V. Jegatheesan, and K. Baskaran, “Problems in seawater industrial desalination processes and potential sustainable solutions: A review,” Reviews in Environmental Science and Bio/Technology, vol. 13, no. 2, pp. 203–214, Nov. 2014, https://doi.org/10.1007/s11157-013-9326-y

T. V. Bartholomew, L. Mey, J. T. Arena, N. S. Siefert, and M. S. Mauter, “Osmotically assisted reverse osmosis for high salinity brine treatment,” Desalination, vol. 421, pp. 3–11, Nov. 2017, https://doi.org/10.1016/j.desal.2017.04.012

M. H. Salih, A. M. Al-Yaqoobi, H. A. Hassan, and A. F. Al-Alawy, “Assessment of the Pressure Driven Membrane for the Potential Removal of Aniline from Wastewater,” Journal of Ecological Engineering, vol. 24, no. 8, pp. 118–127, 2023, https://doi.org/10.12911/22998993/166283

R. H. Salman, H. A. Hassan, K. M. Abed, A. F. Al-Alawy, D. A. Tuama, K. M. Hussein, H. A. Jabir, “Removal of chromium ions from a real wastewater of leather industry using electrocoagulation and reverse osmosis processes,” in AIP Conference Proceedings, Mar. 2020, vol. 2213, no. 1, https://doi.org/10.1063/5.0000201

H. A. Aljendeel, “Removal of Heavy Metals Using Reverse Osmosis,” Journal of Engineering, vol. 17, no. 3, 2011. https://doi.org/10.31026/j.eng.2011.03.23

W. Bai, L. Samineni, P. Chirontoni, I. Krupa, P. Kasak, A. Popelka, N. B. Saleh, and M. Kumar, “Quantifying and reducing concentration polarization in reverse osmosis systems,” Desalination, vol. 554. Elsevier, p. 116480, May 15, 2023, https://doi.org/10.1016/j.desal.2023.116480

D. Şahin, “Forward Osmosis Membrane Technology in Wastewater Treatment,” in Osmotically Driven Membrane Processes, IntechOpen, 2021, https://doi.org/10.5772/intechopen.97483

J. M. Gozálvez, J. Lora, J. A. Mendoza, and M. Sancho, “Modelling of a low-pressure reverse osmosis system with concentrate recirculation to obtain high recovery levels,” Desalination, vol. 144, no. 1–3, pp. 341–345, Sep. 2002, https://doi.org/10.1016/S0011-9164(02)00341-7

H. A. Hassan and A. F. Al-Alawy, “Osmotically assisted reverse osmosis (OARO) for desalination of brackish water,” AIP Conference Proceedings, vol. 2806, no. 1, p. 030017, Sep. 2023, https://doi.org/10.1063/5.0163014

N. Togo, K. Nakagawa, T. Shintani, T. Yoshioka, T. Takahashi, E. Kamio, and H. Matsuyama, “Osmotically Assisted Reverse Osmosis Utilizing Hollow Fiber Membrane Module for Concentration Process,” Industrial and Engineering Chemistry Research, vol. 58, no. 16, pp. 6721–6729, Apr. 2019, https://doi.org/10.1021/ACS.IECR.9B00630

K. Nakagawa, N. Togo, R. Takagi, T. Shintani, T. Yoshioka, E. Kamio, and H. Matsuyama “Multistage osmotically assisted reverse osmosis process for concentrating solutions using hollow fiber membrane modules,” Chemical Engineering Research and Design, vol. 162, pp. 117–124, 2020, https://doi.org/10.1016/j.cherd.2020.07.029

T. V. Bartholomew, N. S. Siefert, and M. S. Mauter, “Cost Optimization of Osmotically Assisted Reverse Osmosis,” Environmental Science and Technology, vol. 52, no. 20, pp. 11813–11821, Oct. 2018, https://doi.org/10.1021/ACS.EST.8B02771

C. D. Peters and N. P. Hankins, “Osmotically assisted reverse osmosis (OARO): Five approaches to dewatering saline brines using pressure-driven membrane processes,” Desalination, vol. 458, pp. 1–13, May 2019, https://doi.org/10.1016/J.DESAL.2019.01.025

C. D. Peters, D. Li, Z. Mo, N. P. Hankins, and Q. She, “Exploring the Limitations of Osmotically Assisted Reverse Osmosis: Membrane Fouling and the Limiting Flux,” Environmental Science and Technology, 2022, https://doi.org/10.1021/acs.est.2c00839

K. Park, D. Y. Kim, and D. R. Yang, “Cost-based feasibility study and sensitivity analysis of a new draw solution assisted reverse osmosis (DSARO) process for seawater desalination,” Desalination, vol. 422. pp. 182–193, 2017, https://doi.org/10.1016/j.desal.2017.08.026

J. Kim, D. I. Kim, and S. Hong, “Analysis of an osmotically-enhanced dewatering process for the treatment of highly saline (waste)waters,” Journal of Membrane Science, vol. 548, pp. 685–693, Feb. 2018, https://doi.org/10.1016/j.memsci.2017.10.048

J. Kim, J. Kim, J. Kim, and S. Hong, “Osmotically enhanced dewatering-reverse osmosis (OED-RO) hybrid system: Implications for shale gas produced water treatment,” Journal of Membrane Science, vol. 554. pp. 282–290, 2018, https://doi.org/10.1016/j.memsci.2018.03.015

X. Chen and N. Y. Yip, “Unlocking High-Salinity Desalination with Cascading Osmotically Mediated Reverse Osmosis: Energy and Operating Pressure Analysis,” Environmental Science and Technology, vol. 52, no. 4, pp. 2242–2250, 2018, https://doi.org/10.1021/acs.est.7b05774

A. T. Bouma and J. H. Lienhard, “Split-feed counterflow reverse osmosis for brine concentration,” Desalination, vol. 445, no. July, pp. 280–291, 2018, https://doi.org/10.1016/j.desal.2018.07.011

X. Li, Y. Mei, J. Zhang, Y. Yang, L. E. Peng, W. Qing, D. He, A. G. Fane, and C. Y. Tang, “Osmotically enhanced reverse osmosis using hollow fiber membranes,” Journal of Membrane Science, vol. 638, no. May, 2021, https://doi.org/10.1016/j.memsci.2021.119703

Y. H. Chiao, Z. Mai, W. S. Hung, and H. Matsuyama, “Osmotically assisted solvent reverse osmosis membrane for dewatering of aqueous ethanol solution,” Journal of Membrane Science, vol. 672, p. 121434, Apr. 2023, https://doi.org/10.1016/j.memsci.2023.121434

Y. Chang Kim and T. Min, “Influence of osmotic mediation on permeation of water in reverse osmosis: Experimental and numerical analysis,” Journal of Membrane Science, vol. 595, p. 117574, Feb. 2020, https://doi.org/10.1016/j.memsci.2019.117574

S. J. Moon, S. M. Lee, J. H. Kim, S. H. Park, H. H. Wang, J. H. Kim, and Y. M. Lee, “A highly robust and water permeable thin film composite membranes for pressure retarded osmosis generating 26 W·m−2 at 21 bar,” Desalination, vol. 483, p. 114409, Jun. 2020, https://doi.org/10.1016/J.DESAL.2020.114409

S. G. Salinas-Rodríguez, Siobhan, J. C. Schippers, and M. D. Kennedy, “Particulate fouling,” IWA Publishing eBooks, pp. 85–124, May 2021, https://doi.org/10.2166/9781780409863_0085

A. F. Al-Alawy, “Forward and Reverse Osmosis Process for Recovery and Re-use of Water from Polluted Water by Phenol,” Journal of Engineering, vol. 17, no. 4, pp. 912–928, 2011. https://doi.org/10.31026/j.eng.2011.04.20

L. F. Greenlee, D. F. Lawler, B. D. Freeman, B. Marrot, and P. Moulin, “Reverse osmosis desalination: Water sources, technology, and today’s challenges,” Water Research, vol. 43, no. 9. Elsevier Ltd, pp. 2317–2348, 2009, https://doi.org/10.1016/j.watres.2009.03.010

G. Han and T.-S. Chung, “Robust and High Performance Pressure Retarded Osmosis Hollow Fiber Membranes for Osmotic Power Generation,” AIChE Journal, vol. 60, no. 3, pp. 1107–1119, 2014, https://doi.org/10.1002/aic.14342




How to Cite

Hassan, H. A., Al-Alawy, A. F., & Al-shaeli, M. (2024). Utilizing Hybrid RO-OARO Systems as New Methods for Desalination Process. Iraqi Journal of Chemical and Petroleum Engineering, 25(1), 23-35. https://doi.org/10.31699/IJCPE.2024.1.3

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