Palm Oil Production Process:
Several unit processes are involved in order to extract palm oil after the fresh fruit bunches (FFB) are transported to the palm oil mills. Two types of oils are produced from oil palm, one is the palm oil from the fibrous mesocarp and another is lauric oil produced from the palm kernel. The major steps of palm oil processing are shown in Figure 2.
Stripping or Threshing:
After sterilization process fruits are stripped and separated from the bunch in a rotary drum stripper. The fruits are lifted and dropped through the stripper in order to be knocked out of the bunches. The detached fruits fall through the space between the bars on the stripper and collected in a bucket conveyor and discharged into a digester. The resulting waste from this step is empty fruit bunches(EFB).
Sterilization:
The initial step in extraction of crude palm oil is sterilization. Fresh fruit bunches (FFB) are sterilized inside autoclave using steam at about 140°C for a period of 75-90 minutes. The purpose of sterilization process is to deactivate hydrolytic enzymes responsible for the breakdown of oil to free fatty acids and to loosen the fruits from bunches. The mucilage will be coagulated due to breaking of oil cells. One of the major sources of wastewater in this step is represented by the steam condensate coming out of the sterilizer.
Digestion:
Digestion process involves the mashing up the fruits under steam heated condition in a digester. The digester is a vertical cylindrical vessel fitted with rotating arms. The action of mashing the fruits under heating is to break the mesocarp oil-bearing cells. Hot w ater is added in digester to enhance the flow of the oils. No residue occurs in this step.
Plam oil Extraction:
Homogeneous oil mash coming out from the digester is passed through a screw press subsequently by a vibrating screen, a hydrocyclone and decanters to remove the fine solids and water. The oil is purified by using the centrifuge and vacuum drier ahead of sending it to the storage tank. The storage will maintain the temperature to 60°C with steam coil heating. The crude oil slurry is then fed into a clarification system for oil separation and purification. The fiber and nuts are separated by passing through the depericarper . The crude palm oil(CPO) contains a mixture of palm oil (35-45%), water (45-55%) and fibrous materials in different portions. After passing the CPO from the screw presser it will be pumped to a horizontal or vertical clarification tank to skim the oil from top of the clarification tank. The crude palm oil is then passed through a high speed centrifuge and a vacuum dryer before being sent to storage tanks. The major wastes of this stage are decanter wastewater and decanter cake.