| 摘要 |
PURPOSE:To enable measurement for a long time by washing a microorganism electrode with a washing liquid which is prepared at pH of 2-5 while a substance blocking the growth of bacteria, none of leaven is added thereto. CONSTITUTION:A microorganism electrode 2 is made up of a diaphragm type oxygen electrode 3 and a microorganism membrane 4. Then, a buffer liquid B such as phosphoric acid buffer liquid is fed to a measuring cell 5 with a pump 9 while a washing liquid N thereto 5 through a changeover valve 13 and the pump 9. Here, the washing liquid N is prepared at pH 2-5 by adding hydrochroric acid slightly to a tap water and also, a substance blocking growth of bacteria none of leavens. Then, the changeover valve 13 is switched over to feed a sample liquid S such as factory liquor through a sampling pump 10 and a filter 18 in place of the washing liquid N and BOD of the sample liquid S is measured with the microorganism electrode 2. When a specified time is reached, the changeover valve 13 is switched over to feed standard liquids C1, C2 and C3 for calibration. |
