New type of supersonic washer-disinfector was developed in order to clean and disinfect reusable medical instruments such as semiconductors, endoscopes and food materials in a short time. This washer has supersonic levitation function with umbrella-shape oscillators and sterilization function with ozone bubbles and silver electrolysis as described in the succeeding paper. Sterilization has been found to be easy and rapid using both ozone oxidation and silver electrolysis. E.coli JM 109 strain (10^3-10^6cells/ml) was killed in 20min either by ozone bubbling or silver electrolysis. S.cerevisiae FY24 strain descending from S288C strain (10^4cells/ml) was killed by silver electrolysis within 0.5min. Bacillus atrophaeus Nakamura1989 NBRC13721 strain descending from ATCC9372 strain (10^4cells/ml), which is most resistant to ethylene oxide gas-sterilization, was killed in 30min by ozone and in 5min by silver electrolysis. Geobacillus stearothermophilus NBRC13737 strain descending from ATCC7953 strain (4×10^4cells/ml), which is most resistant to autoclave sterilization, was killed by silver electrolysis in 5min at 40℃ and in 1 min at 60℃.
