MEMBRANE SEPARATION METHOD, IMMERSION TYPE MEMBRANE SEPARATOR AND MEMBRANE SEPARATION PROCESS

摘要

It is intended to provide a waste water treatment method whereby, in the step of diffusing air in a biological treatment tank in the method of treating soil water (waste water) such as sewage by the membrane separation activated sludge method, the air diffusion efficiency is elevated and low fouling characteristics are established at a low cost without lowering the washing efficiency on the separation membrane surface or inhibiting the function of supplying required air to the activated sludge. Namely, a membrane separation method comprising pooling a microorganism-containing liquid containing activated sludge in a tank and conducting the membrane separation with the use of an immersion type membrane separator provided in the tank, wherein the immersion type membrane separator at least comprises a separation membrane having a surface roughness of 0.1 µm or less and a microbubbling air diffusing unit, which is located below the separation membrane and generates microbubbles, and the separation membrane surface is treated with the microbubbles generated from the microbubbling air diffusing unit so that the microorganism-containing liquid in the tank is subjected to the membrane separation while washing the surface of the separation membrane.