Inactivation effect of pressurized carbon dioxide on bacteriophage Qβ and ΦX174 as a novel disinfectant for water treatment

The inactivation effects of pressurized CO2 against bacteriophage Q beta and Phi X174 were investigated under the pressure of 0.3-0.9 MPa, initial concentration of 10(7)-10(9) PFU/mL, and temperature of 17.8 degrees C-27.2 degrees C. The optimum conditions were found to be 0.7 MPa and an exposure time of 25 min. Under identical treatment conditions, a greater than 3.3-log reduction in bacteriophage Q beta was achieved by CO2, while a nearly 3.0 log reduction was observed for phage Phi X174. The viricidal effects of N2O (an inactivation gas with similar characteristics to CO2), normal acid (HCl), and CO2 treatment with phosphate buffered saline affirmed the chemical nature of CO2 treatment. The pumping cycle, depressurization rate, and release of intracellular substances caused by CO2 were its viricidal mechanisms. The results indicate that CO2 has the potential for use as a disinfectant without forming disinfection by-products.