SEQUENTIAL DISINFECTION OF CRYPTOSPORIDIUM-PARVUM BY OZONE AND CHLORINE DIOXIDE

A two step disinfection approach was evaluated for control of Cryptosp oridium parvum using bench-scale experiments in 0.05 M phosphate buffe r at pH 8 and 22 degrees C. Sequential application of ozone and chlori ne dioxide was evaluated where ozone was applied first followed by chl orine dioxide. Infectivity in neonatal CD-1 mice was used to assess oo cyst viability after disinfection. The sequential treatment of oocysts by ozone followed by chlorine dioxide resulted in additional inactiva tion of C. parvum due to the synergism of the two disinfectants. The i nactivation kinetics for chlorine dioxide were modeled following preco nditioning with ozone at a given level using the Integral-Hem model wh ich takes the disinfectant decay into account. These preliminary findi ngs indicate that sequential disinfection with ozone followed by chlor ine dioxide may have potential in controlling waterborne parasites.