Effects of pressure and pressure cycling on disinfection of Enterococcus sp. in seawater using pressurized carbon dioxide with different content rates.
Interest is growing in a disinfection technique for water treatment without disinfection byproducts. This study presents the result of using a liquid-film-forming apparatus at less than 1.0 MPa for disinfection of seawater. The sensitivity of Enterococcus sp. (ATCC 202155) to the pressurized carbon dioxide (CO2) was examined under various conditions of pressure cycling, pressure, working volume ratio (WVR), and CO2 content rate. The key influences on frequency and magnitude of pressure cycling in enhancing Enterococcus sp. inactivation are elucidated. The results reveal strong correlation between pressure cycling and inactivation efficiency (P-value < 0.001). The outcome of linear regression model analysis suggests that the model can explain 93%, 85%, and 89% of the inactivation efficiency of (25% CO2 + 75% N2), (50% CO2 + 50% N2), and 100% CO2, respectively. The predicted value was fit with experimental results (p-value <0.05). Under identical treatment conditions (pressure = 0.9 MPa, ΔP = 0.14 MPa, 70% WVR, and 20 ± 1°C), treatment with pressurized CO2 (100% purity) resulted in complete inactivation 5.2 log of Enterococcus sp. after 70 cycles within 20 min. The Enterococcus sp. inactivation of pressurized CO2 followed first-order reaction kinetics. The smallest D-value (largest k-value) was induced by pressurized CO2 (100% purity) at 0.9 MPa, which was obtained at 3.85 min (0.5988 min(-1), R(2) ≥ 0.95). The findings could provide an effective method for enhanced bactericidal performance of pressurized CO2, to address recently emerging problems in water disinfection.
a Graduate School of Science and Engineering, Yamaguchi University , Yamaguchi , Japan.|b Department of Environmental Science , Hue University of Sciences, Hue University , Hue , Vietnam.
Loc T T
LT
Dang
c Graduate School of Sciences and Technology for Innovation, Yamaguchi University , Yamaguchi , Japan.
Tsuyoshi
T
Imai
b Department of Environmental Science , Hue University of Sciences, Hue University , Hue , Vietnam.
Tuan V
TV
Le
a Graduate School of Science and Engineering, Yamaguchi University , Yamaguchi , Japan.
Satoshi
S
Nishihara
c Graduate School of Sciences and Technology for Innovation, Yamaguchi University , Yamaguchi , Japan.
Takaya
T
Higuchi
a Graduate School of Science and Engineering, Yamaguchi University , Yamaguchi , Japan.
Mai K D
MK
Nguyen
c Graduate School of Sciences and Technology for Innovation, Yamaguchi University , Yamaguchi , Japan.
Ariyo
A
Kanno
c Graduate School of Sciences and Technology for Innovation, Yamaguchi University , Yamaguchi , Japan.
Koichi
K
Yamamoto
c Graduate School of Sciences and Technology for Innovation, Yamaguchi University , Yamaguchi , Japan.
Masahiko
M
Sekine
D002245:Carbon Dioxide / Q000737:chemistry*; D015169:Colony Count, Microbial; D004203:Disinfection / Q000379:methods*; D016983:Enterococcus / Q000187:drug effects / Q000254:growth & development*; D016014:Linear Models; D011312:Pressure; D012623:Seawater / Q000382:microbiology*; D018508:Water Purification
D002245:Carbon Dioxide
Bactericidal performance; Enterococcus sp.; inactivation effect; pressure cycling; pressurized CO2; water disinfection