Evaluation of Front-Face Fluorescence for Assessing Cyanobacteria Fouling in Ultrafiltration

Cyanobacteria fouling in ultrafiltration (UF) drinking water treatment poses a significant threat to the stability and sustainability of the process. Both phycocyanin found in cyanobacteria and the polymer membrane exhibit strong fluorescence, which could be readily detected using front-face excitation-emission matrix (FF-EEM) spectroscopy. In this study, FF-EEM was employed for the nondestructive and in situ characterization of algae fouling evolution in UF, while also analyzing fouling mechanisms and reversibility. The results indicated that phycocyanin fluorescence on the membrane surface showed a linear correlation with the specific algal cell count on the membrane surface before reaching saturation. As fouling progressed, membrane fluorescence decreased, which was associated with the extent of the surface coverage on the membrane. The plateau in membrane fluorescence indicated full coverage, coinciding with the cake filtration mechanism, cake compression, and deterioration of fouling reversibility. These findings highlight the promise of FF-EEM as a valuable tool for monitoring and evaluating fouling of cyanobacteria in UF systems.