Abstract
The authors designed an improved unit cell-type apparatus equipped with 300 unit cells of 115 dm2 effective membrane-area. This apparatus was operated for more than 10,000 hours, and the following results were obtained:
1. During this long-term operation, there occurred no trouble with the improved pack of membrane and the cell structure. The pack of the membrane proved to be easy to handle.
2. After the unit cell was improved by attaching an out-let hose to the bottom for safer suction of brine, such troubles as resulted from the stagenation of air and brine were not observed during the operation.
3. Even though the removal ratio of salt of feed sea-water was increased up to 30% under the current density of 3.5 amp/dm2, there was observed no trouble.
4. Under-the same condition as in the preceding paragraph 3 and by adding a permselective reagent a, the apparatus continued to indicate over 95% of the ratio of NaCl expressed by the equation of {(Cl-Ca-Mg)(N) ×100/Cl(N)}.
The mean and maximum ratios of NaCl were 95.5% (the amount of the reagent: 0.15ppm, temperature of the feed sea-water: 21-25°C) and 98.8%(the amount of the reagent: 0.2-0.3ppm, the temperature of the feed sea-water: 17°C), respectively.
