| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a water treatment method that can maintain a high salt removal rate and a high permeate flow rate even when hard water of poor water quality is used. <P>SOLUTION: The water treatment method includes: a first reverse osmosis membrane separation step of soft water; and a degassing step of a permeate. Also, the method includes a raw water softening process, a first regeneration process for regenerating the whole of a cation exchange resin bed, and a second regeneration process for regenerating a part of the cation exchange resin bed. In the second regeneration process, a regenerant amount of a regeneration level of 1-6 eq/L-R is supplied to a hardness leak prevention bed. In the softening process, raw water having an electrical conductivity of 150 mS/m or less and a total hardness of 500 mgCaCO<SB POS="POST">3</SB>/L or less is supplied. A negatively chargeable skin layer made of a crosslinked wholly aromatic polyamide is formed on the membrane surface. The RO membrane module 5b has a reverse osmosis membrane having a water permeability coefficient of 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>or more and a salt removal rate of 99% or more when a sodium chloride aqueous solution having a concentration of 500 mg/L of pH 7.0, and a temperature at 25°C is supplied thereto at an operating pressure of 0.7 MPa and at a recovery rate of 15%. <P>COPYRIGHT: (C)2012,JPO&INPIT |
