Properties of UV inactivation of Aggregated Escherichia coli

Abstract

 In order to quantitatively understand the effect of aggregation of bacteria in water on the inactivation effect by UV, UV irradiation is performed on a sample containing E. coli that has been aggregated using alginic acid and calcium ions, and the inactivation effect is determined by the cultural method. The aggregation state of E. coli was adjusted with initial E. coli concentration (10⁶, 10⁷, 10⁸ CFU/mL) and calcium ion concentration (0, 10, 20 mM). As a result, aggregation affected the inactivation effect only when the initial E. coli concentration was 10⁸ CFU/mL, and the inactivation effect was minimized at a calcium ion concentration of 20 mM. This is because when initial E. coli concentration was 10⁸ CFU/mL, it is considered that there were enough E. coli blocking E. coli from UV. This study suggested that the initial E. coli concentration and the size of flocks in the sample affect the inactivation effect of E. coli.