title: Comparison of disinfection effect of pressurized gases of CO2, N2O, and N2 on Escherichia coli.
abstract: Based on the production of gas bubbles with the support of a liquid film-forming apparatus, a device inducing contact between gas and water was used to inactivate pathogens for water disinfection. In this study, the inactivation effect of CO2 against Escherichia coli was investigated and compared with the effects of N2O and N2 under the same pressure (0.3-0.9 MPa), initial concentration, and temperature. 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 by CO2, while 3.3 log and 2.4 log reductions were observed when N2O and N2 were used, respectively. Observation under scanning electron microscopy and measurement of bacterial cell substances by UV-absorbance revealed greater cell rupture of E. coli following treatment with CO2 than when treatment was conducted using N2O, N2 and untreated water. The physical effects of the pump, acidified characteristics and the release of intracellular substances caused by CO2 were bactericidal mechanism of this process. Overall, the results of this study indicate that CO2 has the disinfection potential without undesired by-product forming.
authors.affiliation: Division of Environmental Science and Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Yamaguchi 755-8611, Japan.
authors.forename: Huy Thanh
authors.initials: HT
authors.lastname: Vo
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Imai
authors.forename: Jantima
authors.initials: J
authors.lastname: Teeka
authors.forename: Masahiko
authors.initials: M
authors.lastname: Sekine
authors.forename: Ariyo
authors.initials: A
authors.lastname: Kanno
authors.forename: Tuan Van
authors.initials: TV
authors.lastname: Le
authors.forename: Takaya
authors.initials: T
authors.lastname: Higuchi
authors.forename: Kanthima
authors.initials: K
authors.lastname: Phummala
authors.forename: Koichi
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002245:Carbon Dioxide / Q000494:pharmacology*; D004203:Disinfection; D004926:Escherichia coli / Q000187:drug effects* / Q000528:radiation effects / Q000648:ultrastructure; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects; D009584:Nitrogen / Q000494:pharmacology*; D009609:Nitrous Oxide / Q000494:pharmacology*; D011312:Pressure; D014466:Ultraviolet Rays; D014867:Water
chemical_list: D000900:Anti-Bacterial Agents; D014867:Water; D002245:Carbon Dioxide; D009609:Nitrous Oxide; D009584:Nitrogen
keywords: Bactericidal effect; Escherichia coli; High pressure CO(2); Nitrous oxide; Water disinfection