Patent ID: 10300409

Abstract:
Initial liquid containing fine bubbles is produced by mixing water and air (step S11). Fine bubbles have diameters of less than 1 μm. The density of bubbles in the initial liquid is measured (step S13), and when the measured density is less than a target density (step S14), the initial liquid is heated and reduced in pressure so that the liquid is vaporized (step S15). As a volume of the liquid decreases, the density of fine bubbles increases, and high-density fine bubble-containing liquid is easily obtained. Alternatively, by increasing the density of fine bubbles in the initial liquid with using a filter that does not pass all fine bubbles, high-density fine bubble-containing liquid is easily acquired (step S15). When the density of bubbles in the initial liquid is greater than the target density, the initial liquid is diluted (step S16).