| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a sewage treatment method which enables oxygen supply and membrane surface cleaning by aeration with air, by suppressing viscosity increase resulting from biopolymers in an activated sludge mixture liquor to increase the fluidity of the activated sludge mixture liquor in a membrane separation activated sludge treatment method. <P>SOLUTION: In the sewage treatment method, organic sewage is subjected to activated sludge treatment in a biological treatment system 104, the activated sludge mixture liquor is subjected to solid-liquid separation by an immersion type membrane separator 109 installed so as to be immersed in a membrane separation tank 106 of the biological treatment tank 104, the concentration of the activated sludge in the membrane separation tank 106 is kept high, the oxygen supply to the activated sludge mixture liquor and the membrane surface cleaning of the immersion type membrane separator 109 are carried out by air diffused from an air diffuser 108 disposed below the immersion type membrane separator 109. The biopolymers in the activated sludge mixture liquor in the membrane separation tank 106 are coagulated by an agent to decrease the viscosity of the activated sludge mixture liquor, and the amount of the air diffused from the air diffuser is controlled under a condition where the minimum amount of air required for the membrane surface cleaning is reduced by decreasing the viscosity of the activated sludge mixture liquor. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
