Distinguishing stage 1 and 2 reverse osmosis permeates using fluorescence spectroscopy

Abstract

Fluorescence excitation-emission matrix (EEM) spectroscopy was used to distinguish between two stages of reverse osmosis (RO) permeates as the first step towards investigating the potential application of fluorescence as a monitoring tool for membrane performance. The signal response of several fluorescence peaks present in Stage 1 and Stage 2 RO permeates of an advanced water treatment plant were compared. The humic-like fluorescence region was found to have the largest percentage difference between stages and therefore was the most appropriate for enabling differentiation. Increases in humic-like fluorescence did not correlate with increases in conductivity or dissolved organic carbon measurements. This suggests that fluorescence is a more selective and sensitive method for monitoring the organic composition of RO permeates than established methods. Fluorescence is therefore a promising tool for improved water quality monitoring of RO permeates.

Chemicals in reverse osmosis-treated wastewater: occurrence, health risk, and contribution to residual dissolved organic carbon

“…The bulk characteristics of DOC in RO permeate have been investigated using ion exchange (Fujita et al 1996;Drewes et al 2003), size exclusion chromatography with organic carbon and nitrogen detection (Henderson et al 2010) and fluorescence excitation emission spectroscopy (Singh et al 2009). These studies have shown that DOC in RO permeates do not normally contain organic material of molecular weight greater than 500 Da (Drewes et al 2003), and that, based on Amberlite XAD™ resin fractionation, up to 50% of DOC is hydrophilic (Fujita et al 1996).…”

Characterisation of reverse osmosis permeates from municipal recycled water systems using fluorescence spectroscopy: Implications for integrity monitoring

“…Very little research has been reported on applications of fluorescence spectroscopy for monitoring RO membrane performance. However, preliminary investigations have suggested that the technique may be sufficiently sensitive to detect small variations in RO permeate qualities [33].…”

Online fluorescence monitoring of RO fouling and integrity: analysis of two contrasting recycled water schemes

“…Our preliminary investigations found the technique sufficiently sensitive to detect subtle changes in permeate quality pertaining to differences in direct feed quality within multiple staged RO systems. 23 Parallel factor analysis (PARAFAC) of treatment processes at several advanced recycled water treatment plants (including RO) demonstrated that five common fluorescence components were present in four or more plants in that study and that the information derived from monitoring these components would be equivalent to monitoring full EEMs. 24 The fluorescent component G3 (λ Ex/Em = 350/428 nm) which was described as a wastewater/nutrient enrichment tracer from that study, matched closely with the fluorescent regions commonly described as 'Peak C' (λ Ex/Em = 320-350/410-430 nm).…”