[Environment] What is COD and BOD?

In recent years, environmental requirements have become increasingly strict, and air pollution and wastewater pollution have been listed as one of the key management projects. Here we will briefly explain the meanings of COD and BOD that are often heard in wastewater.

COD chemical oxygen demand

Chemical Oxygen Demand

COD is used to indicate the content of organic matter in water that can be chemically oxidized. The COD value is based on the use of potassium dichromate as an oxidant and heating in the presence of strong acid to oxidize organic matter in the water into carbon dioxide and water. The consumed potassium dichromate is converted into an equivalent amount of oxygen, which is COD. For general industrial wastewater (such as detergents, etc.) or wastewater containing substances that are not easily decomposed by organisms (such as electroplating solutions), COD is used to indicate the degree of pollution. The higher the value, the more serious the pollution.

National regulations database discharge water standards (updated on April 29, 2018) COD required value: less than 100 PPM (chemical industry discharge water category)

BOD biochemical oxygen demand

Biochemical Oxygen Demand

BOD refers to the amount of oxygen consumed by the decomposition and oxidation of organic matter in water that is easily decomposed by microorganisms at a specific time and temperature. Generally called BOD, it refers to the result measured after incubation at 20℃ for 5 days, also called BOD5. BOD can represent the content of biodegradable organic matter in the water, and indirectly also represents the degree of organic matter pollution in the water body.

National regulations database discharge water standards (updated on April 29, 2018) BOD required value: less than 30 PPM (chemical industry discharge water category)