| abstract |
A method is provided with which it is possible to effectively improve the rejection of a membrane without considerably lowering the permeation flux, even when the membrane has significantly deteriorated. The method for improving the rejection of a permeable membrane includes a step (amino treatment step) in which an aqueous solution that contains a compound having an amino group and having a molecular weight of 1,000 or lower and has a pH of 7 or lower (amino treatment water) is passed through the permeable membrane. After this amino treatment step, water having a higher pH than the amino treatment water is passed through the permeable membrane. Thus, by passing the low-molecular amino compound, the part of the membrane which has deteriorated can be repaired without considerably lowering the permeation flux of this permeable membrane, and the rejection can be effectively improved. |