| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an electrodialysis system which can produce water with a nitrate ion concentration suppressed to equal to or less than a water-quality standard value by suppressing superfluous electric power as much as possible when removing nitrate ions by an electrodialyzer. <P>SOLUTION: The electrodialysis system, which electrodialyzes raw water containing at least nitrate ions to obtain treated water whose nitrate ion concentration is equal to or less than the water quality standard value, has a detection part 6 into which the treated water of the electrodialyzer is introduced to detect a nitrate ion concentration in the treated water. The detection part 6 is equipped with a counter electrode of an anode 104 and a detection electrode of a cathode 103, detects a catalytic current generated during reduction of the nitrate ions on the surface of the cathode to measure the nitrate ion concentration, and inputs the measured concentration into a control part 7. The control part 7 judges whether the nitrate ion concentration is within a predetermined range or not. When the nitrate ion concentration is over the upper limit concentration, the control part 7 outputs a directive signal to increase a voltage or current quantity, and when it is less than the lower limit concentration, the control part 7 outputs a directive signal to decrease a voltage or current quantity. <P>COPYRIGHT: (C)2009,JPO&INPIT |
