Electric discharge is going to be applied to bacterici-1 dal inactivation in water without chemical dosing. In this article, 2 the sterilization experiments of simulated reused water from an 3 industrial washing machine were conducted by three different 4 treatment methods: 1) air bubble pulsed discharge (ABPD); 2) O 3 5 alone; and 3) ozone bubble pulsed discharge (OBPD). The results 6 showed that: 1) the highest sterilization effect was obtained by 7 OBPD treatment and 2) since the number of sterilized bacteria 8 by OBPD treatment was larger than the sum of the number 9 of sterilized bacteria by ABPD treatment and that of by O 3 10 alone treatment, the synergistic effect by OBPD treatment exists. 11 In order to clarify the decisive factor of synergistic effect by 12 OBPD treatment, we measured dissolved O 3 concentration, pH, 13 NO − 3 concentration, emission intensities of O radical, and H 2 O 2 14 concentration. As a result, dissolved O 3 concentrations were less 15 than 0.02 mg/L in all conditions, there was no difference in pH 16 from NO − 3 between ABPD treatment and OBPD treatment, there 17 was no difference between emission intensities from O radical 18 generated by ABPD treatment and OBPD treatment, the highest 19 H 2 O 2 concentration was obtained by OBPD treatment, and the 20 number of sterilized bacteria by H 2 O 2 (5.82 mg/L) with O 3 21 (100 ppm) bubble was larger than the sum of the number of 22 sterilized bacteria by H 2 O 2 (5.82 mg/L) with air bubble and O 3 23 alone treatment. From these results, we conclude that the H 2 O 2 24 concentration increase and the AOP by O 3 /H 2 O 2 are the decisive 25 factor of the synergistic effect by OBPD treatment. 26 Index Terms-Dissolved O 3 , hydrogen peroxide, O radical, 27 ozone bubble pulsed discharge (OBPD) treatment, sterilization 28 effect, synergistic effect. 29 I. INTRODUCTION 30 I NDUSTRIAL washing machines are widely used for linen 31 service company to provide clean sheets, uniforms, and so 32 on. In the machine, wash, rinse, and dehydration processes can 33 be carried out with one device. In order to reduce wastewater 34 and water consumption from the industrial washing machine, 35 reused water that is generated after rinse and dehydration 36