Transport and accumulation of organic matter in forward osmosis-reverse osmosis hybrid system: Mechanism and implications

Ming Xie, Stephen R. Gray

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)

Abstract

The productivity and sustainability of forward osmosis (FO) - reverse osmosis (RO) system could be hindered by contaminant accumulxation in the draw solution. A significant, progressive contaminant accumulation was observed when digested sludge was processed by the FO-RO system. The FO-RO system achieved stable water production and high rejections of dissolved organic matter; however, progressive contaminant accumulation was evident in the draw solution. Mechanism for contaminant accumulation was elucidated by examining the passage and accumulation of dissolved organic matter using fluorescence excitation emission matrix (EEM) spectroscopy and size exclusion (SEC) chromatography. Contaminant that accumulated in the draw solution exhibited a distinct signature in the fluorescence EEM spectra at peak T1, suggesting protein-like substance. The molecular weight of the protein-like substance was resolved by SEC chromatography, identifying a molecular weight of 200 g/mol. The molecular weight of the protein-like substance was between the estimated molecular weight cut-offs of RO and FO membranes. As a result, such low molecular weight protein-like substance diffused through the FO membrane, and was largely rejected by the RO membrane by the virtue of steric hindrance mechanism, thereby accumulating in the draw solution of the closed-loop FO-RO system.

Original languageEnglish
Pages (from-to)6-16
Number of pages11
JournalSeparation and Purification Technology
Volume167
Early online date26 Apr 2016
DOIs
Publication statusPublished - 14 Jul 2016

Keywords

  • Contaminant accumulation
  • Dissolve organic matter
  • Forward osmosis
  • Reverse osmosis
  • Steric hindrance

ASJC Scopus subject areas

  • Analytical Chemistry
  • Filtration and Separation

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