Chemical oxygen demand (COD) is a measure of the sum of all substances present in water that can be oxidised under certain conditions. It indicates the amount of oxygen (in mg/l) that would be required for their oxidation if oxygen was the oxidant. The chemical oxygen demand serves in particular as a sum parameter for quantifying the pollution of wastewater with organic substances. It covers both biodegradable and non-biodegradable organic substances, but also some inorganic substances.  

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