CONICET | Buscador de Institutos y Recursos Humanos

Many different species of bacteria suspended in water are responsible for a variety of diseases to human being. One of the most dangerous bacteria that contaminates the environment and causes different pathological disorders is Pseudomonas aeruginosa. This bacterium has a very high natural resistance to various antibiotics and disinfectants. The main objective of this work was to develop a general methodology for studying the inactivation of Pseudomonas aeruginosa in water using Advanced Oxidation Processes (UV, H2O2 and UVC/H2O2). For this purpose, a previously constructed photoreactor was used to carry out the designed experiments. To measure the incident radiation arriving to the reactor, potassium ferrioxalate actinometer runs was employed. Experiments were conducted varying the following operating conditions: (i) UVC radiation alone, (ii) hydrogen peroxide alone and (iii) a combination of UVC with H2O2. Preliminary experiments were conducted to determine the initial concentration of bacteria and, when needed, the initial concentration of hydrogen peroxide. The experimental results show the evolution of the microorganism inactivation reaction with the different selected disinfection methodologies. With UVC radiation alone, inactivation higher than 99.99% was achieved in a short reaction time. Contrarily, hydrogen peroxide alone is not suitable to disinfect Pseudomonas aeruginosa. When the UVC/H2O2 combination was used, results are very different depending upon the H2O2 concentration employed. With oxidant concentration about 50 ppm the highest inactivation rate was achieved as compared with results using UV alone. With lower than 50 ppm or higher than 100 ppm concentrations of hydrogen peroxide the disinfection rate always decreases.