| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a water treatment method of maintaining a high salt removal rate and a water permeate flow even in the case of hard water whose water quality is poor. <P>SOLUTION: This water treatment method has a deionization step to be executed by reverse osmosis membrane separation, and includes: the softening process of raw water; a first reproduction process of reproducing a whole cation exchange resin floor; and a second reproduction process of reproducing a portion of the cation exchange resin floor. In the second reproduction process, a reproduction liquid amount whose reproduction level is 1 to 6eq/L-R is supplied to a hardness leak prevention floor, and in the softening process, raw water whose electric conductivity is equal to or less than 150 mS/m, and whose total hardness is equal to or less than 500 mgCaCO<SB POS="POST">3</SB>/L is supplied to this floor. Furthermore, an RO film module 5b includes a reverse osmosis membrane formed with a skin layer negatively charging of crosslinked wholly aromatic polyamide on a film surface, and has the reverse osmosis membrane which being configured such that when aqueous sodium chloride solution whose concentration is 500 mg/L of pH 7.0, and temperature of 25°C with an operating pressure of 0.7 MPa and recovery rate of 15% is supplied, a water permeation coefficient is equal to or more than 1.5×10<SP POS="POST">-11</SP>m<SP POS="POST">3</SP>m<SP POS="POST">-2</SP>s<SP POS="POST">-1</SP>Pa<SP POS="POST">-1</SP>, and a salt removal rate is equal to or more than 99%. <P>COPYRIGHT: (C)2012,JPO&INPIT |
