| 摘要 |
<p>The present invention addresses the problem of providing a water treatment method for efficiently removing impurities such as suspended substances contained in raw water using a separation membrane, particularly a water treatment method for steadily producing clarified water, which has high water quality enough to be used as supply water for a reverse osmosis membrane unit, using a microfiltration membrane or an ultrafiltration membrane. The means for solving the problem is as follows: a cationic aggregating agent is added to raw water (a) to prepare aggregated primary treated water; the aggregated primary treated water is used as final aggregated treated water without any modification when the zeta potential of the aggregated primary treated water (b) is less than 0 mV, and an anionic substance is added to the aggregated primary treated water (b) so as to adjust the zeta potential of the resultant water to a value less than 0 mV and the resultant water is used as final aggregated treated water when the zeta potential of the aggregated primary treated water (b) is 0 mV or more; and the final aggregated treated water is treated using a separation membrane having a surface zeta potential of less than 0 mV to produce treated water (d).</p> |
