Photocatalytic disinfection of water polluted by pseudomonas aeruginosa

Pathogens in drinking water supplies can be removed by sand filtration followed by chlorine or ozone disinfection. These processes reduce the possibility of any pathogens entering in the drinking water distribution network. However, there is doubt about the ability of these methods to remove chlorine-resistant microorganisms. Concern has also been raised about the production of disinfection by-products following the chlorination process. Photocatalysis by titanium dioxide (TiO2) is a possible alternative/complementary drinking water treatment method. The antibacterial action of heterogeneous photocatalytic process of UV-C/TiO2 has been studied on pseudomonas aeruginosa, a microorganism resistant to chlorine and UV-C irradiation. The TiO2 photocatalytic technology can destroy bacteria, which are resistant to oxidative membrane damage caused by direct UV irradiation. This study aims to further investigate the total mineralization of the bacteria to the extent of death and cell-mass destruction using TiO2-Suspension-photocatalytic oxidation reactor. Pseudomonas aeruginosa is a common soil and aquatic microorganism, which normally is not affected by chlorine and low UV-C irradiation intensity. We studied effect of parameters such as amount of TiO2, irradiation time and presence of ascorbic acid and... on removal of p. aeruginosa. The data, which are obtained in this study, show that the optimum concentration of TiO2 is 325 ppm and at the initial concentration of TiO2 equal to 325 ppm and initial microorganism MPN / 100 ml equal to 300 and after 75 min UV irradiation time, p. aeruginosa removal efficiency was 94.3 %. Removal efficiency of p. aeruginosa in the absence of TiO2 or UV irradiation is very low. Decreasing the concentration of microorganisms increases its removal efficiency. Removal efficiency of sphyroplast cells was more than intact cells of p. aeruginosa, which shows the important role of cell wall on cell resistance against chemical agents. Ascorbic acid has inhibitory effect on this process.