METHOD OF WATER DISPOSAL

摘要

A biological method of water disposal that avoids disadvantages caused by an increase of the number of membrane filter units attributed to an increase of the volume of sludge disposed of, maintaining a given rate of sludge disposed of. Four or more membrane filter units (5) are immersed and laid at given intervals in series in aeration tank (4). The amount of suctioned filtrate water of each membrane filter unit (5) and/or the amount of air emitted toward each membrane filter unit (5) is sequentially increased from the raw water inflow side to the sludge discharge side. Accordingly, in response to the amount of solid matter adhering to the membrane surface of membrane filter units (5) on the sludge recovery side, the solid matter can be unfailingly detached from the membrane surface. Simultaneously, the sludge concentration at edge portions of the recovery side exhibiting the highest sludge concentration would be increased, thereby facilitating the discarding operation of recovered sludge and further realizing reduction of drying energy at discarding. Moreover, the discharge of filtrate water can be efficiently carried out.