NOVELTY - Processing wastewater, involves subjecting organic wastewater in a biological-treatment tank to activated sludge treatment, separating the activated-sludge liquid mixture to solid-liquid, using immersion type membrane separator installed in the tank, supplying oxygen to activated-sludge liquid mixture, when activated-sludge amount in the tank is maintained in high concentration, and cleaning film formed on surface of the separator.    USE - For processing organic wastewater (claimed).    ADVANTAGE - Enables aggregation of the biopolymer present in the activated-sludge liquid mixture of the biological-treatment tank, along with a chemical agent, and reduces the viscosity of the activated-sludge liquid mixture. The air quantity for carrying out aeration is controlled by decreasing the air quantity required for cleaning film formed on the surface of the separator, by reduction of the viscosity of the activated-sludge liquid mixture, thus enabling cost-effective method for treating wastewater.    DETAILED DESCRIPTION - Processing wastewater, involves (a) subjecting organic wastewater (101) in a biological-treatment tank (104) to activated sludge treatment, (b) separating the activated-sludge liquid mixture to solid-liquid, using immersion type membrane separator (109) that is immersed and installed in the biological-treatment tank, (c) supplying oxygen to the activated-sludge liquid mixture, when the activated-sludge amount in the biological-treatment tank is maintained in high concentration, and (d) cleaning the film formed on the surface of the immersion type membrane separator, where the wastewater process uses air for carrying out aeration, supplied by the diffuser (108) arranged in the downward direction of the immersion type membrane separator, and the minimum air quantity for carrying out aeration is controlled by decreasing the air quantity required for cleaning film formed on the surface of the separator, by reduction of the viscosity of the activated-sludge liquid mixture. The wastewater processing enables the biopolymer present in the activated-sludge liquid mixture of the biological-treatment tank, to aggregate along with a chemical agent, and reduces the viscosity of the activated-sludge liquid mixture.    DESCRIPTION OF DRAWING(S) - The figure shows the block diagram explaining the wastewater processing. (Drawing includes non-English language text).    suction pump (10)    organic wastewater (101)    biological treatment tank (104)    membrane-separation tank (106)    diffuser (108)    immersion type membrane separator (109)