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

10 Scopus citations

Abstract

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
Volume27
DOIs
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

Keywords

  • Membrane fouling
  • PHREEQC
  • Reverse osmosis
  • Silica scaling

ASJC Scopus subject areas

  • Geography, Planning and Development
  • Water Science and Technology

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