High silica concentration in RO concentrate

A. H. Haidari*, G. J. Witkamp, S. G.J. Heijman

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Silica scaling is one of the major scaling challenges in Reverse Osmosis (RO). The safe operation practice is to keep the silica concentration below 150 mg/L in RO concentrate. This study addresses the effects of divalent cations such as calcium and magnesium on silica scaling in a seawater RO installation used as a pretreatment to Eutectic Freeze Crystallisation (EFC). Results showed that in the absence of antiscalant and divalent cations a sustained silica concentration of approximately 280 mg/L in concentrate is possible without declining membrane permeability. At a higher concentration of divalent cations, the membrane permeability decreased. Membrane autopsy and analysing destructed membrane showed a relatively low magnesium and a high calcium concentration on the membrane after adding divalent ions into the solutions. It is concluded that in absence of divalent cations and without antiscalant the limits of 150 mg/L silica can be extended to 280 mg/L for 6–8 h.

Original languageEnglish (US)
Article number100171
JournalWater Resources and Industry
StatePublished - Jun 2022

Bibliographical note

Funding Information:
We would like to thank Hatenboer-Water for their support and providing RO-equipment for the experiments and ZERO BRINE ( Horizon 2020 project with grant number 730390 ) for their support for writing this article.

Publisher Copyright:
© 2022 The Authors


  • Membrane fouling
  • Reverse osmosis
  • Silica scaling

ASJC Scopus subject areas

  • Geography, Planning and Development
  • Water Science and Technology


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