Real time Raman based approach for identification of biofouling
Abstract This study describes a proof of concept for a compact real time surface enhanced Raman spectroscopy (SERS) online sensing approach for detection of biofouling in drinking water membrane filtration. In this study we created a custom designed flow cell that mimics a cross flow membrane filtration system. This enables one to measure changes in surface foulants, such as Brevundimonas dimiuta (BD) bacteria and adenine, under conditions that are similar to conventional membrane filtration systems. For measurements we used a common portable Raman spectrometer with a laboratory Raman probe in combination with a specially developed gold nanoparticle (Au NP) SERS sensing area on filter membranes. This allowed real time detection of low concentrations of surface foulants immediately after inoculation into an ultra pure water reservoir under pressure driven filtration conditions. We compared these online results with static measurements from an offline, sample taking approach, using a confocal Raman laboratory microscope. The developed Au NP SERS sensing area on the membranes proved to be stable over a long period of surface fouling investigations and to suppress the strong interfering Raman signal originating from the composition layer of most filtration membranes.