| 主权项 |
1. A method for operating a clarification membrane module which comprises external-pressure type hollow-fiber clarification membranes and in which water to be treated is passed through the clarification membranes from an outer side thereof toward an inner side thereof to obtain filtrate,
the clarification membranes each having a filtrate flow channel and having, at one end thereof, an open end where the filtrate flow channel is open and, at the other end, a closed end where the filtrate flow channel is closed, the method comprising: performing a filtration step in which while keeping the clarification membranes so that a position of the open ends is above a position of the closed ends, water to be treated is filtrated from the other side to the inner side of each clarification membrane and the filtrate obtained is taken out through the open ends; and performing closed-end high-position cleaning step after making the position of the closed ends the position of the open ends, the closed-end high-position cleaning step being either the following step (a) or step (b): (a) closed-end high-position cleaning step A in which the outer side of the clarification membranes within the clarification membrane module is filled with liquid and air scrubbing is then performed by supplying a gas; (b) closed-end high-position cleaning step B in which air scrubbing is performed by supplying a gas, while supplying liquid to the outer side of the clarification membranes within the clarification membrane module. |
