Realtime and In-Situ Monitoring of Membrane Fouling with Fiber-Optic Reflectance UV-vis Spectrophotometry (FORUS)

Organic fouling is a major obstacle to the sustainable application of membrane processes in water treatment. While organic fouling has been extensively studied due to its importance, there exists no current method for in-situ and real-time quantification of the amount of accumulated foulant on the membrane surface. The surface concentration of foulants is the most directly relevant information for quantifying the extent of fouling and is critical for elucidating the mechanism of fouling in membrane processes. Using two most commonly studied foulants, bovine serum albumin (BSA) and humic acid (HA), we demonstrate in this study the feasibility of using fiber-optic reflectance UV–vis spectrophotometry (FORUS) to enable real-time and in-situ measurement of the surface foulant concentrations in ultrafiltration. We first show the existence of a linear correlation between the surface concentration and the UV–vis absorbance measured by FORUS for each type of foulants. We then apply FORUS in ultrafiltration to quantitatively reveal the dynamic behavior of organic fouling.