Chemical oxygen demand

Chemical oxygen demand

In chemistry, COD stands for Chemical Oxygen Demand.
Its value, expressed in milligrams of oxygen per liter (mgO2/L), represents the quantity of oxygen necessary for the complete chemical oxidation of the organic and inorganic compounds present in a water sample.
Together with BOD and TOC it represents one of the parameters commonly used for the indirect measurement of the content of organic substances present in water.
The term “COD” is a measurement used to quantify the amount of oxygen required to oxidize chemicals present in an aqueous solution. In other words, COD is a measure of water pollution caused by chemicals that can be oxidized through chemical reactions. It is often used as an indicator of the amount of organic and inorganic pollutants present in a water sample, such as industrial waste, wastewater or environmental samples.
The determination of COD involves a series of chemical reactions that oxidize the substances present in the water, using a strong solution of potassium dichromate in an acidic environment. The amount of potassium dichromate that is reduced during this reaction is directly proportional to the COD of the water sample. The result is expressed in milligrams of oxygen per liter (mg/L) or parts per million (ppm) and provides an indication of the “chemical oxygen demand” due to the presence of pollutants.
COD is an important measurement in the environmental field and in water management, as it allows us to evaluate the effect of chemical pollution on the aquatic ecosystem and to monitor the effectiveness of wastewater treatment processes to remove pollutants.