Application of Supercritical CO₂ Bubbling to Inactivate E. coli and Coliform Bacteria in Drinking Water

Abstract

The effect of the continuous flow of supercritical CO₂ microbubbles (the SC-CO₂ method) on the inactivation of both Escherichia coli in model water and coliform bacteria in water prior to treatment at a municipal water filtering plant were studied as a way to produce safe drinkable tap water. The number of surviving cells in both samples drastically decreased above a certain concentration of dissolved CO₂ (γ=25). When treated for 13.3min, cells were not detected at concentrations over γ=30. The dependences of the number of surviving cells on the concentration of dissolved CO₂ were similar in both the treatments for 6.7 and 13.3min. Therefore, it was suggested that effective inactivation could be achieved by minimizing the treatment time. From these results, it was proposed that the SC-CO₂ method might be effective in inactivating E. coli and coliform bacteria for the production of public drinking water.