AWWA MTC61148

The objective of this study was to characterize and identify the organic foulants responsible for flux declines of low pressure membranes during periods of more intense microbial activity. Samples were collected from the Urne River (Brittany region - France) after clarification at the Magenta drinking water treatment plant at different periods during the first semester of the year 2003. High Pressure Size Exclusion Chromatography (HPSEC) and Pyrolysis GC/MS analyses were the two major analytical tools used in this study. Time of Flight-Secondary Ion Mass Spectrometry (TOF SIMS) and amino acids and amino sugars analyses were also performed. This work confirmed that during intense microbial activity in the source water (spring, summer time), conventionally treated water exert stronger membrane fouling. HPSEC analyses showed that high molecular polysaccharides and proteins are preferentially sorbed onto the membranes during such period. This study showed that the organic foulant that remains after backwash and chemical cleaning was a mixture of several biopolymers (proteins, polysaccharides, amino sugars and polyhydroxyaromatics). Amino sugars and polysaccharides which originate from microbial activity (microbial cell wall residues and/or exopolymers from DOM constituents and/or biofilm) appeared to be the major constituents of the fouling material. Includes 5 references, tables, figures.