Fouling of ultrafiltration membranes by organic matter generated by marine algal species

Abstract

Controlling fouling in seawater reverse osmosis and ultrafiltration systems is a major challenge during algal blooms. This study investigates UF fouling potential of four marine algae and their algal organic matter (AOM): Chaetoceros affinis (Ch), Rhodomonas balthica (Rh), Tetraselmis suecica (Te), and Phaeocystis globulosa (Ph). Batch culture monitoring of the four different marine algal species showed remarkable differences in their production of biopolymers, transparent exopolymer particles (TEP) and their membrane fouling potential (MFI-UF_{10 kDa}). MFI-UF_{10 kDa} was linearly related to biopolymer concentration, and TEP during the growth and stationary/death phase of all four algal species. But the linear relation of MFI-UF_{10 kDa} with algal cell density and chlorophyll-a concentration did not continue during the stationary/death phase. In experiments with capillary UF membranes, non-backwashable fouling of UF membranes varied strongly for the four different AOM solutions tested, and was linked to the presence of polysaccharides (stretching-OH) and sugar ester (stretching S˭O) groups in the AOM. The non-backwashable fouling coincided with MFI-UF_{150 kDa} and TEP concentration. Therefore, determination of these parameters (MFI and TEP) and correlating with MODIS satellite data may generate useful information about the fouling potential of seawater at different locations during an algal bloom.