A closed-loop forward osmosis-nanofiltration hybrid system: Understanding process implications through full-scale simulation

Sherub Phuntsho, Jung Eun Kim, Seungkwan Hong, NorEddine Ghaffour, TorOve Leiknes, Joon Yong Choi, Ho Kyong Shon

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


This study presents simulation of a closed-loop forward osmosis (FO)-nanofiltration (NF) hybrid system using fertiliser draw solution (DS) based on thermodynamic mass balance in a full-scale system neglecting the non-idealities such as finite membrane area that may exist in a real process. The simulation shows that the DS input parameters such as initial concentrations and its flow rates cannot be arbitrarily selected for a plant with defined volume output. For a fixed FO-NF plant capacity and feed concentration, the required initial DS flow rate varies inversely with the initial DS concentration or vice-versa. The net DS mass flow rate, a parameter constant for a fixed plant capacity but that increases linearly with the plant capacity and feed concentration, is the most important operational parameter of a closed-loop system. Increasing either of them or both increases the mass flow rate to the system directly affecting the final concentration of the diluted DS with direct energy implications to the NF process. Besides, the initial DS concentration and flow rates are also limited by the optimum recovery rates at which NF process can be operated which otherwise also have direct implications to the NF energy. This simulation also presents quantitative analysis of the reverse diffusion of fertiliser nutrients towards feed brine and the gradual accumulation of feed solutes within the closed system.
Original languageEnglish (US)
Pages (from-to)169-178
Number of pages10
StatePublished - Dec 30 2016

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This research was supported under various funding: Industrial Facilities & Infrastructure Research Program (14IFIP-B087385-01) by the Ministry of Land, Infrastructure and Transport of the South Korean Government, King Abdullah University of Science and Technology (KAUST), Saudi Arabia, National Centre for Excellence in Desalination Australia (NCEDA), ARC Future Fellowship (FT140101208) and University of Technology Sydney chancellor's postdoctoral research fellowship.


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