Clarification and Purification Of Digesting and Pressing Palm Oil Mill Plant The Crude Oil extracted in the Twin Screw Press contains varying amounts of water together with impurities like sand, vegetable matter etc. in the form of insoluble solids, some of which is dissolved in the water. These impurities are now removed in the different steps in Clarification section. This involves separating the diluted crude oil in a continuous settling tank into a relatively clean and dry top oil fraction and and lower sludge fraction. Both these fractions are now centrifuged separately. The sludge water is sent to a Decanter to separate the solids and clear water+ oil. The oil layer is purified in a centrifuse to remove all dirt and fibre remaining. The oil will be dried in high vacuum driers before storage to prevent any FFA build-up, due to the presence on any dissolved water.