If the chemistry is right..
... free fatty acids don't stand a chance. The caustic soda added to the crude oil reacts with the FFAs to form sodium soaps. Centrifugal separators then remove the soaps from the crude oil. The neutral oil is subsequently bleached and deodorized. This method can be used for reliably refining virtually all crude oils, including oils of low quality, with the exception of castor oil.
In chemical refining caustic soda is used to neutralize free fatty acids.
The standard neutralization process is called exactly this, Standard Neutralization. It is the most common method to neutralize pre-degummed oils or oils with only a low phosphatide content.
Feedstock: Virtually all oils, including and especially low quality oils, except castor oil.
What to consider:
Benefits:
Cold refining
Feedstock: for oils that contain waxes and have relatively low FFA contents, e.g. sunflower oil
What to consider
Benefits:
Soapstock splitting