Photocatalytic inactivation of Cryptosporidium parvum with TiO(2) and low-pressure ultraviolet irradiation.
This study investigated the efficacy of low-pressure ultraviolet (UV) irradiation and the synergistic effect of UV/titanium dioxide (TiO(2)) photocatalysis on Cryptosporidium parvum oocyst inactivation. At UV doses of 2.7, 8.0, and 40mJ/cm(2), oocyst inactivation was 1.3, 2.6, and 3.3log(10), respectively. Reactive oxygen species (ROS) generated by longwave UV radiation (>315nm) and TiO(2) achieved less than 0.28-log inactivation. However, the synergistic effect of germicidal (254nm) UV and TiO(2) resulted in 2-log and 3-log oocyst inactivation with 4.0 and 11.0mJ/cm(2), respectively. Therefore, using TiO(2) in combination with UV reduced the dose requirement for 3-log inactivation by 56%. An approximate 1-log decrease in inactivation of oocysts was observed with nanopure water in comparison to buffered water, whereas changes in pH from 6 to 8 had little effect on the photocatalytic inactivation of oocysts in either matrix (P>0.1).
Department of Civil and Environmental Engineering, National Science Foundation Water Quality Center, Arizona State University, ECG 252, Tempe, AZ 85287-5306, USA.
Hodon
H
Ryu
Daniel
D
Gerrity
John C
JC
Crittenden
Morteza
M
Abbaszadegan
D000818:Animals; D002384:Catalysis; D045744:Cell Line, Tumor; D016785:Cryptosporidium parvum / Q000187:drug effects* / Q000528:radiation effects*; D006801:Humans; D010777:Photochemistry; D014025:Titanium / Q000494:pharmacology*; D014466:Ultraviolet Rays
C009495:titanium dioxide; D014025:Titanium