With extraction by pressure and centrifugation, water remains in the oil and it must be eliminated before reaching the packaging phase. This process can take place in two ways: by decantation and by vertical centrifugation.
Decantation is the traditional method of separation, based on the principle that oil and water do not mix. The oil must is made to rest in masonry tanks, so that the oil rises to the surface, separating from the water. This process takes quite a long time and the extracted oil quality is not optimal, which is why it has been almost completely abandoned.
The vertical centrifugation system is the one used in all plants to separate the oil from the water. The centrifugal separator is formed by a tank which contains the rotating drum, formed by a series of perforated and superimposed conical discs. The oil must enters the drum from above and is centrifuged at a speed of 6000/6500 rpm. As a result of the different densities and centrifugal force, the water and the oil separate and flow out separately. Both the oil must and the vegetation water obtained during horizontal centrifugation are subjected to this process.