[Comparative photodynamic effect of methylene blue in solution and immobilized on Escherichia coli and Bacillus...

The photodynamic activity of Methylene Bleu (MB) in homogeneous aqueous solution and in heterogeneous phase was compared in order to experiment the disinfection of waters and waste waters using the photosensitation technique. Insolubilized MB was obtained by covalent bonding on a styrene - 2% Divinylbenzene copolymer. E. coli and B. subtilis were used as gram-positive and gram-negative test microorganism. In the present experimental condition high inactivation towards both microorganism was obtained without substantial difference between homogeneous and heterogeneous phases. Therefore the photooxidation with immobilized BM seem to exalte the potential advantage of this technique in water disinfection for the remarkable bactericidal activity associated with the oossibility of the reuse of the photosensitizer.