Membrane biofouling by microbial products adversely impacts the feasibility of adopting membrane bioreactors (MBRs) for treating wastewater. The fouling layer structure determines the pressure drop across the fouling layer. Three-dimensional distributions of nucleic acids, proteins, alpha-D-GLUCOPYRANOSE POLYSACCHARIDES, AND B-D-glucopyranose polysaccharides in the fouling layer formed on a mixed cellulose ester membrane were generated utilizing a quadruple staining protocol combined with confocal laser scanning microscopy (CLSM). For the first time, this study constructed a three-dimensional volumetric grids model representing the fouling layer structure on the basis of a series of CLSM images. Quantitative structural information about the fouling layer was extracted from the CLSM images.

OATAO is an open access repository that collects the work of some Toulouse researchers and makes it freely available over the web where possible. This is an author's version published in: a b s t r a c t Literature on the design of efficient nonfouling membranes by in-situ modification is poor, which can be explained by the difficulty to control membrane formation mechanisms when a third material is added to the casting solution, or by the lack of stability of matrix polymers with surface-modifiers. We present polyvinylidene fluoride membranes formed by vapor-induced phase separation and modified with a tri-block copolymer of poly(styrene) and poly(ethylene glycol) methacrylate moieties (PEGMA 124 -b-PS 54 -b-PEGMA 124 ). After characterizing the copolymer, we move onto membrane formation mechanisms. Membrane formation is well controlled and leads to structure close to bi-continuous. Considering the formulation chosen, PVDF/PEGMA 124 -b-PS 54 -b-PEGMA 124 solutions are less viscous and more hydrophilic than virgin PVDF solutions. Both effects promote non-solvent transfer, thus decreasing the chances for crystallization. Hydrophilic capability of membranes is increased from about 59 mg/cm 3 to 650 mg/cm 3 , leading to a severe drop of non-specific protein adsorption, up to 85-90%, also depending on its nature. Biofouling at the micro-scale by modified Escherichia coli and Streptococcus mutans is almost totally inhibited. Finally, biofouling is importantly reduced in dynamic conditions, as measured from the water flux recovery ratio of 69.4%, after 3 water-BSA filtration cycles, much higher than with a commercial hydrophilic PVDF membrane (47.3%). These membranes hold promise as novel materials for water-treatment or blood filtration. n Corresponding authors.

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