Effect of the surface modification of polymer membranes on their microbiological fouling

Composite polymer membranes with chemically different surfaces are prepared by the photochemical modification of Millipore microfiltration poly(vinylidene fluoride) and polysulfone membranes using 2-acrylamido-2-methyl-1-propanesulfonic acid, 2-hydroxyethyl methacrylate, and 2-(dimethylamino)ethyl methacrylate quaternized with methyl chloride. It is shown that, during the filtration of an E. coli suspension, the membrane flux substantially decreases with time owing to the fouling of the membrane surface by bacterial cells. The membranes with the hydrophilic surface are less susceptible to fouling than hydrophobic membranes, while the ability to recover the performance upon washing is higher for the membranes with a chemically neutral surface than for charged membranes. It is shown that the susceptibility of membranes to microbiological fouling reduces with a decrease in the roughness of the membrane surface. It is established that the membranes modified with the quaternized 2-(dimethylamino)ethyl methacrylate possess antibacterial properties. These membranes proved to be the most efficient in the filtration of natural surface water in a noncontinuous regime, a result that is explained by the ability of membranes to prevent the formation of a fouling biofilm on their surfaces.