| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for treating water, in each of which when the water which is to be treated contains a BOD component and a polyvalent inorganic cation, is treated by using an RO membrane separation unit and the treated water is recovered, the decrease of a flux and the biofouling, each of which is caused by the adhesion of organic matter onto the surface of a membrane in the PO membrane separation unit, are prevented and a COD value of RO concentrated water is decreased efficiently to prevent a bad influence of the RO concentrated water on waste water treatment. <P>SOLUTION: A biodegradable scale inhibitor and an alkali are added to the water to be treated to adjust the pH of the water to be treated to≥9.5. The resulting water is made to pass through the RO membrane separation unit 4. The RO concentrated water is treated biologically. Since the pH of the water to be supplied to the RO membrane separation unit is adjusted to≥9.5, the biofouling in the RO membrane separation unit can be prevented, the adhesion of a nonionic surfactant onto the surface of the membrane can be prevented and the decrease of the flux can also be prevented. The clogging of the membrane surface by calcium carbonate scale under a high pH condition is restrained by adding the scale inhibitor. Since the RO concentrated water is treated biologically by using the biodegradable scale inhibitor and the biodegradable scale inhibitor in the RO concentrated water is biodegraded, TOC can be decreased. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
