Siphon-type air diffusion device, membrane bioreactor, and water treatment method

A siphon-type air diffusion device for intermittently performing aeration, comprising:

• at least two siphon-type air diffusion pipes;
• and
• an air supply member that supplies air to the siphon-type air diffusion pipes,
• wherein each of the siphon-type air diffusion pipes includes
• a siphon chamber which includes a first portion and a second portion, wherein the second portion is on the downstream side of the first portion,
• a communication portion which connects the first portion of the siphon chamber to the second portion of the siphon chamber,
• an air diffusion hole which is provided on the downstream side of the siphon chamber,
• a path which extends from the siphon chamber to the air diffusion hole, and
• a treatment water inlet which is provided on the upstream side of the siphon chamber,
• wherein the air supply member includes
• a distribution pipe which extends in a direction in which the siphon-type air diffusion pipes are arranged, and
• one or more introduction portions branched from the distribution pipe, wherein each of the introduction portions includes at least one air supply port supplying air to one of the siphon-type air diffusion pipes,
• wherein the distribution pipe is provided above the air supply port, and
• wherein in the air supply port of each of the introduction portions, the air supply port located at the uppermost position in the vertical direction is provided below a lower end of a partition wall dividing the siphon chamber and the path.