Application of Fluorescence Spectroscopy to Track Membrane Fouling, Failure, and Contaminants in Water and Wastewater System

Due to growing scarcity of fresh water resources, the water industry is increasingly exploring the option of water reuse to meet the need for potable water supplies. However, water reuse projects are still facing challenges with public acceptance due to unfavorable perceptions regarding the reuse of wastewater and lack of advanced water quality monitoring tools. Fluorescence spectroscopy has been recommended for water quality and insitu monitoring. The overall goals of this study, therefore, were 1) to evaluate the potential of fluorescence spectroscopy to track small changes of dissolved organic matter (DOM) during membrane filtration due to fouling and 2) to detect the presence of other contaminants using a 3D bench-top fluorometer in comparison with an insitu C3 submersible fluorometer.;In membrane fouling experiments with different water types, the percentage removal of protein-like fluorescent organic matter was greater than the removal of humic-like organic matter, indicating preferential retention of protein-like compounds by ultrafiltration membrane. In addition, the percentage removal of DOM fluorescent peaks was always highest just after the backwash process. These results demonstrate that water quality drops with fouling. Results from the assessment of temperature effect on DOM fluorescence showed that temperature greatly affects DOM fluorescence intensities, and this effect is increasingly more pronounced at higher DOM fluorescence intensities. An equation relating measured and reference temperatures and fluorescence intensities with a temperature correction constant constant (-0.0155) was shown to be widely applicable for correcting temperature for CDOM fluorescence but not for tryptophan-like (TRP) fluorescence. Results demonstrate that the root mean squared error (RMSE) method investigated here produced the best fit to the reference temperature for both CDOM and TRP fluorescence. For instances in which insitu fluorescence data are sparse or data are unavailable at the reference temperature (20°C), specific correction constants were recommended. In contaminant addition experiments, the TRP fluorescence sensor had a linear and significantly positive relationship with contaminant concentration. Results using the insitu fluorometer compared well with those of the bench-top fluorometer. Overall, results suggest fluorescence is well suited to monitoring water quality of high quality permeate or product water in water reuse facilities and contaminants.