Abstract
The ultrasonic sterilizing method is environmentally safe because of using non-chemicals. We have made a prototype of an ultrasonic sterilizer which induces cavitation utilizing the squeeze-film effect. Our previous experimental results shows that the prototype called "the ultrasonic sterilizing cell" can efficiently inactivate Cryptosporidium oosysts. The ultrasonic sterilizing cell can treat only a small amount of water, but the cost of treatment is much lower than the cost of the conventional ultrasonic treatment of water. For the treatment of a large amount of water, the specifications of water treatment systems consisting of the cells in series and parallel are theoretically investigated from the view point of reaction kinetics. There is a probability that a few kilowatt system will be able to treat about 100m^3 per day of water contaminated by Cryptosporidium oosysts with high efficiency. The system is expected to treat filter backwash water.
