episode 5 >> FINAL SEPARATION OF OIL FROM WATER
This is the final step. Depending on what equipment was used in the extraction process, this may be unnecessary. When a hydraulic press is used and the liquid output is a mix of oil and water, with microscopic bits of olives, this final separation of oil from water is obviously required. In the case of separation with a centrifuge, when the product is almost completely oil, this step can still be beneficial (especially in the case of very ripe, overwatered olives when the oil has not separated perfectly in the first centrifugation), but it is not always an absolute necessity.
Separation by Gravity: The oil and water are put into tanks where they separate by gravity. This method is not used in any modern facility. It is inexpensive from an equipment point of view but very time-consuming, bulky, and leads to wasted oil if the separation is incomplete. It can also lead to a deterioration of the oil.
Like a cream separator in a dairy, the liquid is spun, separating the heavier water from the oil. Vertical centrifuges with perforated conical discs can act as either:
- Purifier: they take a little water out from mostly oil. This is the most common case.
- Skimmer: they take a little oil from a lot of water (if the goal is to scavenge the wastewater).
- Clarifier: removes a little solid from a liquid phase (removes microscopic particles from the oil).
- It is a quick step.
- The process is continuous.
- It is very efficient and results in higher yield than gravity separation.