Effect of colder stream temperature control on energy utilization, flux, RSF, and membrane integrity in asymmetric temperature FO systems

Muhammad Saqib Nawaz, Talal Alamoudi, Sofiane Soukane, M. Obaid, Noreddine Ghaffour*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Water and energy are key components to assess the feasibility of any water treatment technique. For industrial applications of forward osmosis (FO), energy optimization needs to be explored further. Asymmetric temperature conditions, having different feed solution (FS) and draw solution (DS) temperatures, are likely to occur in industrial FO applications and are least explored. Some standard practices are followed without any scientific evidence of their impact on the system performance and energy utilization, like maintaining the colder stream temperature instead of letting it reach a steady state with the hotter stream. This study compares water flux, reverse solute flux (RSF), and energy utilization when the colder stream temperature is maintained and not maintained. Thin film composite-poly amide (TFC-PA) and cellulose triacetate (CTA) membranes were used at laboratory-scale in 24 h batch experiments with 0.75 M NaCl as DS and DI water as FS. All possible configurations of membrane orientation (AL-DS and AL-FS) and streams heating and cooling strategies were studied. The module material was made up of plexi-glass with 4 cm thick plates and flexible tubing of PVC was used. Results revealed that under not maintained conditions, on average, the water flux increased by 9.1–17%, RSF increased by 13.8–27.3%, and energy consumption reduced by 75.8–67% with CTA and TFC membranes, respectively. Therefore, if the RSF is not the primary concern of the application, it is advantageous not to maintain the colder stream temperature. However, it is recommended that scientists verify and compare the efficiencies between maintained and not maintained temperatures under their specific experimental conditions.

Original languageEnglish (US)
Pages (from-to)67-77
Number of pages11
JournalProcess Safety and Environmental Protection
StatePublished - May 2022

Bibliographical note

Funding Information:
The research reported in this paper was supported by King Abdullah University of Science and Technology ( KAUST ), Saudi Arabia. The help, assistance, and support of the Water Desalination and Reuse Center ( WDRC ) staff are greatly appreciated.

Publisher Copyright:
© 2022 The Institution of Chemical Engineers


  • Asymmetric temperature
  • Energy optimization
  • Forward osmosis
  • Reverse solute flux
  • Water-energy nexus

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • General Chemical Engineering
  • Safety, Risk, Reliability and Quality


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