Influence of Oxygen, pH, and Temperature on E. coli Lethality in Ultrasound

The aim of this study was to investigate the effects of oxygen and other influences i.e., pH, temperature, and contact time upon the destruction of E. coli in ultrasound technology. The lethal capacity on E. coli of oxygenized ultrasonic were carried out at different pH (4, 7 and 10), temperatures (25, 35, and 50 degrees C), and exposure time (1, 2, 4, 6, 9, 12, and 15 min). Comparing to the conventional application of ultrasonic bath, the oxygenized ultrasonic was applied by adding a strong oxidizing agent, oxygen gas. At DO 8, the highest E. coli destruction was yielded. The best results also occurred at pH 4 and temperature 50 degrees C. The numbers of the E. coli decreased with time. In other words, at pH 4 and temperature 50 degrees C, the efficiency of E. coli reduction was as much as 83.17 % after 15 minutes of exposure in oxygenized ultrasonic, whereas it was only 50.24 % in conventional ultrasonic. The oxygen dissolved in the water, pH, and temperature showed statically significance (p<0.05) on influencing the destruction of E. coli.