Determination of total organic carbon and the application to water pollution control
1972 Volume 27 Issue 6 Pages 551-565
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1972 Volume 27 Issue 6 Pages 551-565
As indices for water pollution control, the biochemical oxygen demand (BOD), chemical oxygen demand (COD) and dissolved oxygen (DO) have usually been adopted to evaluate the amount of organic components in wastewater. Recently, however, the quality of ordinary wastewater has become, due to the enormous increase in urban population and industrial growth, too complicated to examine. For this reason, the water pollution problem has been qualitatively changed.
An advanced tequnique to determine organic carbon in water has recently been introduced by several researchers, who stressed the importance of Total Organic Carbon (TOC) for the classification of water pollution. Therefore, studies of the relationship among BOD, COD, and TOC appear to clarify the nature of organic constituents present in wastewater.
In this paper, the author investigated the relationship among the 3 indices, BOD, COD, and TOC, which were obtained from Raw Sewage (R.S.), Secondary Effluent (S.E.) from the Kagoshima Sewage Treatment Plant (processed with activated sludge) and River Water (R.W.) in Kagoshima city.
There were significant correlations between BOD and TOC, COD and TOC, and BOD and COD, respectively, in R.W. and S.E.; and also between BOD and TOC, and COD and TOC in R.S. The correlation between COD and TOC was stronger than that between BOD and TOC or that of BOD and COD in R.S. and R.W.
The ratios, BOD to COD, BOD to TOC, and COD to TOC, were calculated from each sample. The ratio, BOD to COD, was more than 0.6 in both R.S. and R.W. and was 0.33 in S.E. The ratio, BOD to TOC was 2.13 in R.S. and 0.93 in S.E. These results show that both R.S. and R.W. contain a large amount of organic substances which are readily oxidized biologically. In the type of river water studied, enhanced oxygen consumption following an increase of organic substances will finally lead to irreversible water pollution. The ratio, COD to TOC, was almost equal in R.S. and S.E. Judging from the extremely small amount of TOC in S.E., it is suggested that there is successful processing of R.S. with activated sludge in the treatment plant.
