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Chemical Oxygen Demand (COD) |
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A characteristic quantity for the quality of water and the pollution of the water (of the Sewage) with Organic Compounds. This also takes account of the quantity of oxygen required for the oxidation of the Organic Compounds. Potassium dichromate is used as a general rule as the chemical oxidizing agent. The COD generally produces higher values than the Biological Oxygen Demand, since it also takes account of substances which do not readily decompose. Chlorinated Hydrocarbons A designation used for Organic Compounds which contain one or more Chlorine atoms. Chlorinated Hydrocarbons are of very considerable importance industrially as the raw materials for plastics (e.g. vinyl chloride used in the manufacture of PVC), as synthetic Solvents (e.g. trichlorethane, trichlorethylene, chloroform), as Insecticides (e.g. chlordane, lindane, DDT) and many other, even mor desirable products. Certain chlorinated Hydrocarbons are included in in the highly dangereous Environmental Poisons. Their danger can be expressed in terms of both their considerable chemical stability, which obstructs their rapid Decomposition into harmless substances, their high liposolubility, which favours good reception and accumulation in living organisms, and their high Toxicity. Moreover, a considerable proportion of the chlorinated Hydrocarbons also have Cancer-producing characteristics. |