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KMID : 0353019690060020201
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Korean Journal of Public Health
1969 Volume.6 No. 2 p.201 ~ p.209
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Environmento-Medical Study on Industrial Sewage
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Abstract
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The pollution of water resources is so rapidly increased in urban and industrial areas that special measures should be taken to prevent and control the pollution. Domestic sewage is treated easily without any special effort in the biological waste treatment plant, but some industrial wastes are not because of the presence of inhibitory substances.
A study was carried out to find the inhibitory effects of some waste components, such as thiourea, dithiooxamide, potassium cyanide, ethanol and sodium chloride, which were frequently found in the industrial wastes, on nitrification and the removal of biochemical oxygen demend.
Main findings obtained are as follows:
1. The strongest inhibitor on nitrification was thiourea at 30% of nitrate to that of control after eration of 16 hours with loading 1 ppm of thiourea, nitrate contents were 45% at loading 1 ppm of dithiooxamide, 80% at 1 ppm ethanol, and 69% at 0.5% scdium chloride.
2. The strongest inhibitor on the biochemical oxygen demand, B.O.D. removal was also thiourea at 43 ppm of B.O.D. with loading 1 ppm of thiorea while B.O.D. of control was 16 ppm, and B.O.D. with loading 1ppm of ethanol and 0.5% of sodium chloride, 1 ppm of potassium cyanide, 10 ppm of ethanol and 0.5% of sodium chloride were 35 ppm, 26 ppm, 45 ppm and 25 ppm respectively.
3. Removal of biochemical oxygen demand was proportionally retarded as the inhibitory effect on nitrification was incteased.
4. The combined effect of two mixed inhibitors was greater than that of any of the individual ones when an inhibitor was present alone at the same concentration as in the mixture.
5. The inhibition effect on nitrification was reduced with the successive loadings of same inhibitor, Nitrate content was not completely recovered after 8 days with first loading of 1 ppm thiourea while the recovering periods of nitrification were 5 days with second loading of 1 ppm thiourea and 5 days with third loading of 2 ppm.
6. The effect of thiourea on nitrification lasted longer than that of any of the inhibitors, that is, the nitrification process was not completely reovered after.
7. days of aeration with loading 1 ppm thiourea while the recovering period was 4 days with 10 ppm ethanol.
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