Identification of organic foulants of nanofiltration membranes used for drinking water production

The goal of our work was, on the one hand, to characterize and identify the nature of the organic foulants responsible for flux declines of high pressure membranes and to the other hand, to evaluate the efficiency of chemical cleaning.

Thus, membrane autopsy was conducted on nanofiltration membranes isolated before and after cleaning from the Méry-sur-Oise filtration train. Elemental analysis, Pyrolysis GC/MS, FT-IR, ¹³C- NMR analyses were performed on both insoluble and soluble phases of the deposit extracted from NF modules. Results confirmed the microbial origin of the fouling material. Polysaccharides and aminosugars were found to be the major organic constituents of the fouling material. In addition, the inorganic content (calcium, phosphorous and aluminum as major constituents) was found to increase significantly from stage 1 to stage 3 of the filtration train. After chemical cleaning a significant reduction of the inorganic content was noticed, however the organic composition of the foulant remained almost unchanged.