(430e) Real-Time Monitoring Approach and System for Detection and Characterization of RO Membrane Fouling

Mineral scaling and membrane fouling remain significant impediments in reverse osmosis (RO) membrane desalination of various water sources, including inland brackish water, seawater and wastewater effluent for water reuse. In order to mitigate membrane fouling and mineral scaling it is imperative to be able to monitor the onset of the above in real time, particularly for water sources of high mineral scaling propensity. Accordingly, a novel membrane monitoring system was developed (for RO plant monitoring) consisting of a high-pressure transparent membrane cell and an automated detection system for high resolution optical scanning of the membrane surface. System pressure and feed flow rate are self-adjusted using a custom control system so as to set the desired level of concentration polarization in the membrane channel, at the desired level relative to that which is expected in the RO plant. Online image analysis software, which is integrated into the control system, analyzes the extent of mineral scaling to quantify the extent of surface coverage by particulate fouling or mineral scale and the number density of mineral crystals. Equipped with fluorescent marker injection and an inline spectrometer for monitoring, the integrated monitoring system also provides the capability for characterization of the feed-side mass transfer coefficient and marker rejection, thereby enabling estimation of the level of concentration polarization in the RO plant. The overall approach has been tested for operational scenarios in which calcium sulfate (gypsum), calcium carbonate (calcite), and silica are the mineral scalants of concern.