河水,海水,下水,屎尿に於けるB.O.D.とC.O.D.との関係について

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In the study of organic substances found in sewage or other geographical environments where pollution by bacteria and the waste matter often happens, one inrariably encounters a problem of the choice of the methods of test: Which is better, a method based on the measurement of biochemical oxygen demand (B.O.D.) or a method based on the estimation of chemical oxygen demand (C.O.D.)? In an attempt to compare and correlate the results of experiments with B.O.D. and C.O.D., the author carried out tests on both B.O.D. and C.O.D. of the organic matter contained in the samples of sea water, river water, sewage and night soil. The results are summarized as follows : (1) Both B.O.D. and C.O.D. of the samples of river water obtained at low tide were higher than those of the samples obtained at high tide. At both low and high tides, the samples of the surface water of a river showed higher B.O.D. and C.O.D. values than those of the water obtained from its bottom. It appeared that a slight shower caused B.O.D. and C.O.D. of river water to fall, a medium rainfall caused them to rise and prolonged rain lasting several days caused them to fall. (2) Like samples of river water, those of sea water showed higher B.O.D. and C.O.D. values at low tide than at high tide. (3) Tests for comparison of B.O.D. and C.O.D. of the samples of sewage and those of the 1:2 dilution of identical samples, both kept to stand at a room temperature, showed that the decrease of B.O.D. and C.O.D. and the decrease of the ratio B.O.D./ C.O.D. were more marked in the latter than in the former. (4) It was shown that the degree of dilution of any samples of raw night soil and its supernatant paralleled the fall in the values of their B.O.D. and C.O.D. the rate of fall being a little smaller than the degree of dilution. (5) Tests in which samples of supernatant of night soil and their dilutions were kept standing at 30℃ and 37℃ in incubators showed that B.O.D. and C.O.D. of the samples kept at 37℃ fell earlier than those of the samples kept at 30℃. (6) It was shown that, from the standpoint of stochastics, there were significant differences between B.O.D. and C.O.D. in all the samples from river water, sea water, sewage and night soil. This indicates that there will be an agreement between the result of tests by chemical method of oxygen demand based on the use of KMnO_4 and the result of tests by biochemical method of determination of oxygen demand, if organic matters to be tested are of similar character.
千葉大学の論文
1959-01-28

河水,海水,下水,屎尿に於けるB.O.D.とC.O.D.との関係について

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