Two types of bacteria were used: E. coli uc4100 (a representative gram-negative bacterium) and staphylococcus aureus (a representative gram-positive bacterium). If we will find the effect on these two bacteria, we will get the similar effect on other bacteria. We varied the concentration of bacteria in electrolytes and discharge time. The experimental result is shown in Fig. 11 for E. coli. A similar result was also obtained for Staphylococcus aureus. After a 20 s discharge, almost all bacteria were killed and after a 30 s discharge, all bacteria were killed. The numbers of both bacteria decreased quickly with increasingdischarge time. Therefore, SPP is very effective in killing bacteria in water.