Fouling potential evaluation by cake fouling index: Theoretical development, measurements, and its implications for fouling mechanisms

Yongxun Jin, Younggil Ju, Hyunkyung Lee, Seungkwan Hong

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)


Current fouling indices typically employed in RO practices, such as silt density index (SDI) and modified fouling index (MFI), have suffered greatly from their inability to predict actual fouling potential primarily due to the erroneous interpretation of fouling mechanisms. Our findings clearly demonstrated that the effect of pore blocking should be excluded during fouling index measurements to simulate real RO applications. Thus, new concept of cake fouling index (CFI) was developed in order to accurately evaluate true fouling cake layer resistance. Specifically, the CFI was determined through consecutive filtration tests by subtracting the flux decline of the secondary filtration from that of the first one to eliminate the effect of pore blocking. The results proved that CFI better predicts the degree of fouling rate in RO experiments than MFI. It was also revealed that it could be utilized as a useful tool for identifying and evaluating the fouling mechanisms. Through a comparison of MFI and CFI, it was shown that pore blocking was enhanced as much as cake formation when pH decreased, while divalent cations (Ca2+) increased only cake formation on the membrane surface. This newly developed index refining existing MFI method is expected to provide more precise information about RO membrane fouling, especially for the design of effective pretreatment processes.

Original languageEnglish
Pages (from-to)57-64
Number of pages8
JournalJournal of Membrane Science
Publication statusPublished - 2015 Sept 5

Bibliographical note

Funding Information:
The authors would like to thank the Ministry of Land, Infrastructure and Transport for supporting this study through the Seawater Engineering & Architecture of High-Efficiency Reverse Osmosis (SEAHERO) program. We would also like to thank Doosan Heavy Industries & Construction for supporting the following projects: ‘Development of a Fouling Index Using MMAS and A Manual for the Application of Pilot Plant’ .

Publisher Copyright:
© 2015 Elsevier B.V.

Copyright 2020 Elsevier B.V., All rights reserved.


  • Cake fouling index (CFI)
  • Fouling mechanism
  • Modified fouling index (MFI)
  • RO membrane fouling
  • Silt density index (SDI)

ASJC Scopus subject areas

  • Biochemistry
  • General Materials Science
  • Physical and Theoretical Chemistry
  • Filtration and Separation


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