Method for upgrading low-value and waste fats, oils, and greases

A method comprising:

• free fatty acid (FFA) stripping of a starting composition to provide a composition comprising about 5 wt. % to about 15 wt. % free fatty acids;
• subsequent to FFA stripping, contacting the composition with a caustic solution to produce a first mixture;
• separating from the first mixture a caustic-treated composition and producing an aqueous waste with a pH from about 2.0 to about 5.0;
• combining the caustic-treated composition with silica particles to produce a slurry;
• and
• removing the silica particles from the slurry to produce a treated composition;
• wherein:
• the composition comprises:
• one or more of animal fats, animal oils, plant fats, plant oils, vegetable fats, vegetable oils, greases, and used cooking oil,
• about 10 wppm or more of total metals;
• about 8 wppm or more of phosphorus;
• about 10 wppm or more of sulfur;
• about 20 wppm or more of nitrogen;
• and
• has an acid number from about 10 mg KOH/g to about 150 mg KOH/g;
• the treated composition comprises:
• a wt. % of free fatty acids about that of the composition;
• and
• less total metals, phosphorus, sulfur, and nitrogen than the composition;
• and
• the silica particles have an average particle size from about 10 microns to about 50 microns and a BET surface area from about 200 m2/g to about 1000 m2/g.