Exploring the differences between forward osmosis and reverse osmosis fouling

Siddiqui, Farrukh Arsalan, She, Qianhong, Fane, Anthony G. and Field, Robert (2018) Exploring the differences between forward osmosis and reverse osmosis fouling. Journal of Membrane Science, 565. pp. 241-253. ISSN 0376-7388

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Official URL: https://doi.org/10.1016/j.memsci.2018.08.034

Abstract

A comparison of alginate fouling in forward osmosis (FO) with that in reverse osmosis (RO) was made. A key experimental finding, corroborated by membrane autopsies, was that FO is essentially more prone to fouling than RO, which is opposite to a common claim in the literature where deductions on fouling are often based solely on the water flux profiles. Our theoretical analysis shows that, due to a decrease in the intensity of internal concentration polarization (ICP), and thus an increase in the effective osmotic driving force during FO fouling tests, the similarity of experimental water flux profiles for FO and RO is in accordance with there being greater fouling in FO than RO. The specific foulant resistance for FO was also found to be greater than that for RO. Possible explanations are discussed and these include the influence of reverse solute diffusion from draw solution. Whilst this explanation regarding specific foulant resistance is dependent on the draw solution properties, the finding of greater overall foulant accumulation in FO is considered to be a general finding. Additionally, the present study did not find evidence that hydraulic pressure in RO plays a critical role in foulant layer compaction. Overall this study demonstrated that although FO has higher fouling propensity, it offers superior water flux stability against fouling. For certain practical applications this resilience may be important.

Item Type: Article
Uncontrolled Keywords: Forward osmosis, Reverse osmosis, Fouling, Internal concentration polarization (ICP), Cake-enhanced concentration polarization (CECP)
Subjects: C900 Others in Biological Sciences
F200 Materials Science
H300 Mechanical Engineering
H800 Chemical, Process and Energy Engineering
H900 Others in Engineering
Department: Faculties > Engineering and Environment > Mechanical and Construction Engineering
Depositing User: Rachel Branson
Date Deposited: 25 Feb 2020 12:26
Last Modified: 25 Feb 2020 12:30
URI: http://nrl.northumbria.ac.uk/id/eprint/42212

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