Sugars and their derivatives are contained in various effluents and consume dissolved oxygen in environmental water. Therefore investigations on the COD and BOD values caused by sugars are necessary. Semimicro COD method previously reported was adopted in this experiment and the following results were obtained. COD values of acidic and alkaline method increased as straight line with increasing sugar concentration, but declined when KMnO
4 remaining in the reaction solutions was reduced. COD values (g/g) increased with the carbon number contained in monosugars and with the number of sugars in oligosaccharide. COD values of ketoses were a little higher than aldoses. Effect of AgNO
3 on the COD of monosugars was not recognized, but the effect appeared in the first period of COD treatment. In the saccharose, AgNO
3 effect represented a little. In glucosamine and galactosamine, AgNO
3 effect was clearly recognized, but the effect diminished in N-acetylglucosamine. Ration of COD values to theoretical oxygen demand was 58.1% in acidic method and 51.4% in alkaline method. This suggests that the oxidation of sugars is incomplete and decomposed products remain in the solution after COD treatment. Mean decomposition rate of BOD values was 42.9% in sugars and 21.6% in sugar alcohols. Therefore COD values indicate content of sugars more direct than BOD.
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