| 摘要 |
<p>PROBLEM TO BE SOLVED: To improve the scraping effect by liquid to be treated on the surface of a separating membrane and provide the permeable flux stable at all times by dividing the inside of a treatment tank into a plurality of areas, providing a circulating flow generating device for circulating the liquid to be treated in the treatment tank and providing membrane separating devices in central sections of respective areas. SOLUTION: The inside of a treatment tank 20 for storing liquid to be treated is divided into a plurality of areas S1-S3 by interstructures 21, 21 in the up and down direction, and the upper and lower sections of the areas S1-S3 are communicated with adjoining areas. Air is fed into the treatment tank 20 by an aeration device 23 disposed on a bottom section of the central area S1, and an upward flow of the liquid to be treated is formed in the area S1, while a downward flow is formed in the areas S2 and S3, and a circulating flow is formed as a whole. Membrane separating devices 25 in which hollow yarn membranes are hung in the lateral direction are disposed between collection pipes 26 connected with a suction pump 29 almost on the central sections of respective areas S1-S3. Cake layers accumulated on the membrane surfaces can be released efficiently by the above arrangement, and a permeable flux can be retained stably.</p> |
