| 摘要 |
The present invention provides a membrane filtration system ( 1 ) including: a filtering membrane portion ( 3 ) for removing impurities in feed water; a drain line ( 16 ) for draining a part of concentrate from the filtering membrane portion ( 3 ) to an exterior of a system; a concentrate return line ( 17 ) for returning a remainder of the concentrate from the filtering membrane portion ( 3 ) to an upstream side of the filtering membrane portion ( 3 ); a return flow rate adjusting portion ( 28 ) for concentrate provided in the concentrate return line ( 17 ); and a control portion ( 30 ) controlling the return flow rate adjusting portion ( 28 ) based on a drain flow rate of the concentrate or a flow rate of product water from the filtering membrane portion ( 3 ). With this construction, it is possible to suppress wasteful power consumption in a feed pump ( 7 ) for feeding water to the filtering membrane portion ( 3 ) and to prevent clogging in the filtering membrane in the filtering membrane portion ( 3 ).
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