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

The present technology provides a method that includes contacting a composition with a caustic solution to produce a caustic-treated composition; 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 includes one or more of animal fats, animal oils, plant fats, plant oils, vegetable fats, vegetable oils, greases, and used cooking oil and the composition includes: at least about 10 wppm of total metals, at least about 8 wppm of phosphorus, at least about 10 wppm of chlorine, at least about 10 wppm of sulfur, at least about 20 wppm of nitrogen, at least about 5 wt. % of free fatty acids; and has an acid number from about 10 mg KOH/g to about 150 mg KOH/g, and the silica particles has a particle size from about 10 microns to about 50 microns, a BET surface area from about 200 m2/g to about 1000 m2/g.