Method and system of wastewater treatment using facultative-organism-adapted membrane bioreactor

A method of upgrading a common membrane bioreactor into a facultative-organism-adapted membrane bioreactor, the common membrane bioreactor comprising a reaction vessel comprising separators and a front reaction zone, the method comprising:

• a) demolishing the separators or the front reaction zone of the reaction vessel;
• b) cutting down an aeration rate of a blower or reducing the arrangement of aeration pipes of an aeration system to enable a dissolved oxygen concentration in over 50% of the reaction vessel to be greater than 0 and smaller than 1.0 mg/L, a dissolved oxygen concentration in the reaction vessel excluding the membrane separation system to be greater than 0 and smaller than 2.0 mg/L, and a dissolved oxygen concentration in the reaction vessel excluding the membrane separation system to be greater than 0 and smaller than 1.0 mg/L;
• and controlling the dissolved oxygen concentration in the membrane separation system to be higher than the dissolved oxygen concentration in the reaction vessel excluding the membrane separation system;
• and
• c) demolishing or stopping a sludge discharge system, a sludge return system and sludge treatment equipment.