Well, cannot be calculated, each one measured alone.

An oxygen component is important for the oxidation of many compounds containing iron, copper, manganese, etc., or other nitrogenous or sulfuric compounds. These compounds consume oxygen in the water for the purpose of conversion to oxides.

The amount of oxygen consumed by these compounds can be measured during Chemical transformation, which in itself is a basic measurement and important in determining the quality of water and is known as the chemical demands of oxygen and may be called sometimes the chemical demand for oxygen and known as the symbol (COD) (Chemical oxygen demand) and known as the amount of oxygen required to complete The chemical oxidation of chemically oxidizable substances in water is expressed in units of mg (oxygen) / liter of water. This measurement is actually indicative of the total amount of chemical compounds dissolved in water as contaminants and chemically oxidizable. The greater the value of oxygen consumed, This means that the concentration of these pollutants is higher.

Sincerely

you have to measure the COD firstly with a spectrophotometer , then you will use the value of CDO to determine the volume of samples you need to measure the BOD

BOD is a subset of COD. The COD analysis oxidizes organic matter that is both chemically and biologically oxidizable. If a reliable correlation between COD and BOD can be established at @a particular site, the simpler COD test may be used in place of the more complicated BOD analysis.