Abstract
According to “Cryptosporidium countermeasures in waterworks” from the Ministry of Health, Labour and Welfare in Japan, usage of UV was conditionally accepted. However, since disinfection effects are determined by the UV dose, which is expressed by the multiplication of the UV dose rate and the distributing residence time, in general the prediction of the disinfection effect is difficult.
In this study, inactivation experiments and tracer experiments were conducted using two UV disinfection reactors and prediction of the performance of one reactor whose efficiency was higher than the results of another reactor which had a more uniform UV dose rate was attempted. From the results, the predicted value of the disinfection effect using a newly developed modified radial light demonstrated the measured value appropriately rather than with radial light. Moreover, when modified radial light was used, it turned out that the disinfection effect was in the range from the UV dose calculated by UV dose rate on the inner surface of the outside reactor tube, to the average UV dose rate.
