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One of the main limitations of membrane applications for water treatment is biofouling,which causes a decrease of membrane performances and is often very difficult to remove bychemical cleanings. To act preventively, membrane pretreatment has to be optimized tominimize the biofouling potential of the feedwater.This study compares different pretreatment processes implemented upstream fromnanofiltration (NF), and their ability to reduce of biofouling on NF elements.Two identical one-stage NF membrane pilots were fed different water qualities from two watertreatment plants in France (Neuilly-sur-Marne and Choisy-le-Roi) during several long filtration tests.Both pilots included a pretreatment step made of pH neutralization, 20 and 6 m cartridgefiltration (except during test 4), and antiscalant injection. UV disinfection was realized by a pilot reactor containing a low pressure UV lamp operated at400 J/msup2/sup. At the end of every test, NF spiral-wound modules were autopsied and analyzed. Thefouling deposit was characterized by ATR-FTIR spectroscopy and by epifluorescencemicroscopy (DAPI staining for total bacteria counts, SYTO9-propidium iodide for live/deaddistinction, FTIC and TRITC-conjugated lectins for exopolysaccharides visualization). Thedeposit dry weight, wettability, ATP and proteins contents were also determined. This study highlights the importance of pretreatment to control biofouling on NF membranes. Includes 17 references, tables, figures.

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Edition: Vol. - No. Published: 11/01/2009 Number of Pages: 15File Size: 1 file , 930 KB