Membrane separation type activated sludge treatment method and system

A membrane separation activated sludge treatment system comprising:

• a tank configured to perform biological treatment on waste water, and an apparatus configured to perform membrane separation on water having been treated in the biological treatment tank,
• wherein the membrane separation apparatus includes a plurality of filtration modules including a plurality of hollow fiber membranes arranged adjacent to one another and oriented in one direction and a pair of holding members fixing both ends of the plurality of hollow fiber membranes, and a plurality of cleaning modules supplying air bubbles from beneath the filtration modules,
• an amount of treated water sucked by the filtration modules and an amount of air bubbles supplied by the cleaning modules are varied in response to variations in an inflow rate of the waste water into the biological treatment tank, and
• the amount of air bubbles supplied by the cleaning modules is varied so that a variation rate of the amount of air bubbles supplied by the cleaning modules is greater than a variation rate of the amount of suction by the filtration modules.