Chemical oxygen demand (COD) is commonly used to represent the amount of organic materials in the water which can be chemically oxidized. Under acidic conditions, with potassium dichromate as the oxidizing agent, the water is heated and organic compounds can be fully oxidized to carbon dioxide and water. The amount of potassium dichromate consumed could be used to calculate the amount of oxygen required which is namely COD. COD is commonly used to represent the degree of pollution in industrial wastewater.