AWWA WQTC65967

Application of membrane nanofiltration (NF) for surface water treatment requires water pretreatment prior to NF elements in order to minimize membrane fouling. In this study, the biofouling potential of three different pretreated river waters was compared. Water A and water B were used to feed two parallel pilot trains and water C fed a pilot unit, part of the drinking water plant of M?ry-sur-Oise (France). During this study, membrane performance parameters (permeability and pressure drop) were continuously monitored. At the end of the experiment, the membrane modules were autopsied and the composition and organization of membrane foulants were characterized by Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy, DAPI staining, lectin-binding analysis, and fluorescence microscopy. The ATR-FTIR spectra and fluorescence microscopy observations of the fouled membranes revealed the presence of a biofilm at the membranes surface for the three feed waters. The microbial cells were mainly organized as microcolonies interspersed at the membrane surface. Polysaccharide residues were found in areas where microcolonies were present and in areas devoid of microorganisms. A positive correlation was observed between organic carbon concentration of feed waters and the biofouling extent at the membrane surface: the higher the dissolved organic carbon (DOC) concentration of feed water, the higher the sessile bacteria counts and relative IR signal (peaks indicative of proteins and polysaccharides). In conclusion, for the three water qualities studied, the DOC concentration was a relevant parameter to determine the biofouling potential of the pretreated waters. Includes 12 references, figures.