Method for the pretreatment of a biofuel feedstock

1. A method comprising

contacting a composition with an aqueous solution to yield a mixture, 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 5 wt. % or more of free fatty acids,

about 10 wppm or more of total metals,

about 8 wppm or more phosphorus,

about 20 wppm or more of nitrogen, and

the aqueous solution comprises diammonium dihydrogen ethylenediaminetetraacetate (“(NH 4 ) 2 H 2 EDTA”), tetraammonium ethylenediaminetetraacetate (“(NH 4 ) 4 EDTA”), a monoammonium salt of diethylenetriaminepentaacetic acid, a diammonium salt of diethylenetriaminepentaacetic acid, a triammonium salt of diethylenetriaminepentaacetic acid, a tetraammonium salt of diethylenetriaminepentaacetic acid, pentaammonium diethylenetriaminepentaacetate (“(NH 4 ) 5 DTPA”), a combination of citric acid and tetrasodium ethylenediaminetetraacetate (“Na 4 EDTA”), a combination of citric acid and disodium ethylenediaminetetraacetate (“Na 2 H 2 EDTA”), a combination of citric acid and a monosodium salt of diethylenetriaminepentaacetic acid, a combination of citric acid and a disodium salt of diethylenetriaminepentaacetic acid, a combination of citric acid and a trisodium salt of diethylenetriaminepentaacetic acid, a combination of citric acid and a tetrasodium salt of diethylenetriaminepentaacetic acid, a combination of citric acid and pentasodium diethylenetriaminepentaacetate (“Na 5 DTPA”), or a combination of any two or more thereof; and

centrifuging the mixture to yield a first treated composition, wherein the first treated composition has less total metals and less phosphorus than the composition.

2. The method of claim 1 , wherein, prior to centrifuging, a caustic solution is added to the mixture.

3. The method of claim 2 , wherein the caustic solution comprises an aqueous ammonium hydroxide solution, aqueous potassium hydroxide solution, aqueous sodium hydroxide solution, or a combination of any two or more thereof.

4. The method of claim 1 , wherein, prior to centrifuging, water is added to the mixture.

5. The method of claim 1 , wherein the method further comprises

combining the first treated composition with an adsorption media to generate a slurry; and

separating a second treated composition from the slurry;

wherein the second treated composition has an amount of total metals and an amount of phosphorus that is about 20% or less than the amount of total metals and an amount of phosphorus in the composition.

6. The method of claim 5 , wherein the adsorption media comprises one or both of silica and diatomaceous earth.

7. The method of claim 6 , wherein the adsorption media comprises both silica and diatomaceous earth, and the adsorption media has a weight ratio of diatomaceous earth to silica of about 0.1:1 to about 1.5:1.

8. The method of claim 1 , wherein during the contacting, a weight ratio of the composition to (NH 4 ) 2 H 2 EDTA in the aqueous solution is about 50:1 to about 500:1.

9. The method of claim 1 , wherein during the contacting, a weight ratio of the composition to (NH 4 ) 4 EDTA is about 50:1 to about 500:1.

10. The method of claim 1 , wherein during the contacting, a weight ratio of the composition to Na 4 EDTA in the aqueous solution is about 50:1 to about 500:1.

11. The method of claim 1 , wherein the combination of citric acid and Na 4 EDTA comprises a molar ratio of citric acid to Na 4 EDTA of about 1:3 to about 3:1.

12. The method of claim 1 , wherein the combination of citric acid and Na 2 H 2 EDTA comprises a molar ratio of citric acid to Na 2 H 2 EDTA of about 1:3 to about 3:1.

13. The method of claim 1 , wherein during the contacting, a weight ratio of the composition to (NH 4 ) 5 DTPA in the aqueous solution is about 50:1 to about 500:1.

14. The method of claim 1 , wherein during the contacting, a weight ratio of the composition to Na 5 DTPA in the aqueous solution is about 50:1 to about 500:1.

15. The method of claim 1 , wherein the combination of citric acid and Na 5 DTPA comprises a molar ratio of citric acid to Na 5 DTPA of about 1:3 to about 3:1.

16. The method of claim 1 , wherein composition comprises about 5 wt. % to about 15 wt. % free fatty acids.

17. The method of claim 1 , wherein the contacting comprises high shear mixing of the composition and the aqueous solution.

18. The method of claim 1 , wherein the first treated composition comprises about 1 wppm or less of sodium soaps.

19. The method of claim 1 , wherein the method further comprises hydroprocessing the first treated composition.

20. The method of claim 5 , wherein the method further comprises hydroprocessing the second treated composition.