BOD (Biochemical Oxygen Demand) Determination is a simple and easy way for monitoring the microorganisms’ activity in water samples with extremely reliable results. 

In particular, microorganisms present or inoculated in a water sample containing biodegradable organic substance, consume oxygen for their metabolic activity and produce a corresponding volume of carbon dioxide. 

The carbon dioxide get absorbed by a strong alkali positioned in the neck of the bottle. The result of this process is a decrease in gas pressure. The BOD measure this change in gas pressure between the beginning to the end of the analysis and give a result expressed in mg/l .