| 摘要 |
PURPOSE:To prevent the lowering in capacity of a semipermeable membrane, by supplying raw water after ion exchange treatment, the addition of a chlorine type sterilizing agent and pH adjustment to the semipermeable membrane composed of a cellulosic derivative. CONSTITUTION:After raw water is subjected to ion exchange treatment, a sterilizing agent such as sodium hypochlorite, hydrogen peroxide or sodium bisulfite is added to raw water in a range of 0.01-1ppm. Subsequently, raw water is adjusted to pH 4.0-6.5 and supplied to a semipermeable member formed using cellulose, cellulose acetate, cellulose butyrate or methyl cellulose as a polymer component to be treated. By this method, the lowering in the performance of the semipermeable membrane is suppressed to reduce trouble and the long-term stable operation of a process is made possible. |
