Inactivation of Giardia Intestinalis by Peroxone Process（ H2O2/ O3） and Its Disinfection Mechanisms

The efficency of peroxone（ H2O2/ O3） to inactivate Giardia intestinali（ G. intestinali） was investigated by the fluorescence staining method and vitro excystation. In order to investigate the mechanisms of inactivation,such as cell surface or inner cell components damage,they were comparatively examined by scanning electron microscopy（ SEM）,protein assay,and DNA gel analysis. When independent addition of O3 was under 1. 5mg·L- 1and contact time reached 10. 0 min,the inactivation rate achieved 99. 6%. At the same time,to achieve the same inactivation effect by H2O2/ O3,1. 0 mg·L- 1O3（ [H2O2]/[O3] = 0. 8） with7. 0 min was required. Results suggest that hydroxyl radicals（ ·OH） was the principal factor during the H2O2/ O3 process by testing the effect of t-butyl alcohol（ TBA） and concentration change of H2O2. Although disinfectant potency of have its drawback of residual effect is transitory, but H2O2/ O3 could further strengthen the capability of inactivation, as well as reducing O3 dosage significantly. Meanwhile,SEMprotein assay,and DNA gel analysis indicate that H2O2/ O3 can destroy the cell surface,degrade the protein,and damage the genomic DNA of G. intestinali.