Ultrasonic treatment apparatus and fine bubble supply method

A fine bubble supply method, comprising supplying, when performing a predetermined treatment on an object to be treated while applying ultrasonic waves to a treatment part capable of accommodating a treatment liquid and the object to be treated, the treatment liquid containing fine bubbles to the treatment part, wherein

• an ultrasonic generator that is provided in the treatment part and applies ultrasonic waves to the object to be treated, and a circulation path for circulating the treatment liquid in the treatment part are provided with respect to the treatment part, wherein:
• the circulation path has a circulating pump for circulating the treatment liquid, a treatment liquid extraction pipe that connects a treatment liquid extracted from the treatment part to the circulating pump, and a treatment liquid discharge pipe that discharges a treatment liquid passed through the circulating pump to the treatment part;
• and
• a fine bubble generator which performs deaeration on the extracted treatment liquid and generates fine bubbles in the treatment liquid, is provided to the circulation path, in series with the treatment liquid extraction pipe, wherein
• the fine bubble generator has two or more narrow portions each having an opening flow path of the treatment liquid with a size narrower than an inside diameter of the treatment liquid extraction pipe, in which the opening flow paths of the narrow portions adjacent to each other are configured to prevent the treatment liquid from proceeding straight, wherein:
• regarding each of the narrow portions, when an opening cross-sectional area of the inside diameter of the treatment liquid extraction pipe is set to A0, and an opening cross-sectional area of the inside diameter of the treatment liquid extraction pipe at an i (i is an integer of 1 or more)-th narrow portion from the treatment part side toward the circulating pump side is represented as Ai, an opening cross-sectional area ratio Ri of the i-th narrow portion represented as Ai/A0 satisfies the following formula (1);
• and
• when an interval between the i-th narrow portion and an i+1-th narrow portion is represented as Li, the following formula (2) is satisfied, and
• when the number of the narrow portions is set to N, and an N-th opening area ratio from the treatment part side toward the circulating pump side is represented as RN, the following formula (3) and formula (4) are satisfied,
• Ri=0.10 to 0.50 Formula (1)
• 1.0≤Li/2(A0/π)0.5≤5.0 Formula (2)
• Ri+1≥Ri Formula (3)
• RN/R1≥1.10 Formula (4).