| 摘要 |
PROBLEM TO BE SOLVED: To provide a separative membrane-cleaning method which can always ensure stable chemical cleaning and normalize a membrane differential pressure by certainly removing deposits on a membrane surface, and to provide a separative membrane cleaning device. SOLUTION: A highly concentrated sodium hypochlorite solution stored in a chemical liquid tank 6, is diluted with membrane-treated and the separative membrane 3 is cleaned using the chemical liquid. In this case, an ammoniacal nitrogen concentration contained in the membrane-treated water, is watched with the help of a monitor 9, and a controller 8 adjusts a dilution ratio by controlling a chemical liquid injection pump 7, in compliance with the above concentration as an index. Thus, it is possible to keep the concentration of the sodium hypochlorite as specified in backwash water, even in case there is a fluctuation in the water quality of the membrane-treated water, and thereby, to prevent a fluctuation in the chemical cleaning effect. COPYRIGHT: (C)2008,JPO&INPIT
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