Abstract: In order to research the synergistic effect of H₂O₂/O₃ inactivating Cryptosporidium parvum in water, factors including the proportions of H₂O₂ and O₃, the effect of hydrogen peroxide, and the inorganic metal ion were investigated by using fluorescence staining method. It could achieve the desired inactivation of Cryptosporidium parvum(inactivation rate above 99.0%). H₂O₂ not only reduces the initial concentration of bactericide (O₃ dosage of 2.0 mg/L), but also shortens the sterilizing time (7.0 min). The best H₂O₂/O₃ molar ratio is 0.8. Common ions in water, such as divalent metal ions Ca²⁺, Mg²⁺ and Cu²⁺ play catalytic roles in the inactivation, while Na⁺ has no obvious effect on the inactivation, and NO^-₃, HCO^-₃ and Cl^- restrain the inactivation of Cryptosporidium parvum to some extent.

Key words: Cryptosporidium parvum;H₂O₂/O₃, drinking water, inactivation