Disinfection Using Pressurized Carbon Dioxide Microbubbles to Inactivate Escherichia coli, Bacteriophage MS2 and T4

This study investigated the potential application of pressurized CO2 for water disinfection. Under supporting high pressure, a high volume of CO2 microbubbles were produced in a liquid environment. Specifically, the inactivation effects of CO2 against Escherichia coli, bacteriophage MS2 and T4 were examined at equal pressures (0.3 - 0.9 MPa) and temperatures. The optimum conditions were found to be 0.7 MPa and an exposure time of 25 min. Under identical treatment conditions, a greater than 5.0 log reduction in E. coli was achieved, while over 3.0 log and nearly 4.0 log reductions were observed for phage MS2 and phage T4, respectively. Comparison of the inactivation effect of CO2, N2O, a common acid and buffer solution against phage MS2, revealed that the change in pH caused by CO2 plays an important role in its virucidal effects. Moreover, the pumping cycle and depressurization rate contributed to the inhibition of microorganisms. Overall, the results of this study indicate that CO2 has the potential for use as a disinfectant without the formation of by-products.