Methods of dewatering algae for diesel blend stock production

• US 8,308,950 B2
• Filed: 05/17/2012
• Issued: 11/13/2012
• Est. Priority Date: 04/06/2010
• Status: Expired due to Fees

• Current Assignee: Heliae Development, LLC (PT Perusahaan Perkebunan London Sumatra Indonesia Tbk)
• Original Assignee: Heliae Development, LLC (PT Perusahaan Perkebunan London Sumatra Indonesia Tbk)
• Inventors: Kale, Aniket
• Primary Examiner(s): Drodge, Joseph
• Application Number:
  US13/473,912
• Publication Number:
  US 20120228224A1
• Time in Patent Office: 180 Days
• Field of Search: 443/05, 443/07, 446/05, 47/14, 210/632, 210/634, 210/638, 210/639, 210/656, 210/749, 210/770, 210/774, 210/806, 435/134, 435/262, 435/267, 435/271, 435/272, 554/12, 554/20, 554/21, 554/174, 554/175
• US Class Current: 210/634
• CPC Class Codes: A61P 7/00 Drugs for disorders of the blood or the extracellular fluid
• CPC Class Codes: B01D 11/04 of solutions which are liquid
• CPC Class Codes: C11B 1/10 by extracting
• CPC Class Codes: C11B 1/108 after-treatment, e.g. of miscellae
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel

Abstract

Methods for selective extraction and fractionation of algal lipids and algal products are disclosed. A method of selective removal of products from an algal biomass provides for single and multistep extraction processes which enable efficient separation of algal components. Among these components are neutral lipids synthesized by algae, which are extracted by the methods disclosed herein for the production of renewable fuels.

Claims

1. A method of dewatering a wet algal cell culture, comprised of intact algal cells and water, and producing a diesel blend stock comprising:

a. removing a portion of the water from a wet algal cell culture to obtain a first wet algal biomass fraction having a lower water content than the algal cell culture, and a first liquid fraction, the algal cells of the first wet algal biomass fraction having a quantity of chlorophyll;

b. mixing a first water miscible solvent set, comprising one or more solvents, with the first wet algal biomass fraction to generate a first dewatering mixture comprised of a second liquid fraction and a second wet algal biomass fraction, wherein the second wet algal biomass fraction comprises intact algal cells, and the algal cells of the second wet algal biomass fraction contain about the same quantity of chlorophyll as the algal cells of the first wet algal biomass fraction, and the second wet algal biomass fraction has a lower water content than the wet algal cell culture;

c. separating the second liquid fraction from the second wet algal biomass fraction;

d. mixing a second water miscible solvent set, comprising one or more solvents, with the second wet algal biomass fraction to generate a second dewatering mixture comprised of a third liquid fraction and a third wet algal biomass fraction;

e. separating the third liquid fraction from the third wet algal biomass fraction, wherein the third wet algal biomass has a lower water content than the second wet algal biomass and comprises intact algal cells;

f. combining the third wet algal biomass with a first amphiphilic solvent set, the solvent set comprising one or more amphiphilic solvents, to make a first extraction mixture, wherein the weight of the amphiphilic solvent set is about the same as the weight of the third wet algal biomass;

g. separating the first extraction mixture into a first liquid phase comprising proteins and a first solid phase;

h. combining the first solid phase with a second amphiphilic solvent set to make a second extraction mixture, wherein the weight of the amphiphilic solvent set is about the same as the weight of the first solid phase;

i. separating the second extraction mixture into a second liquid phase comprising polar lipids and a second solid phase;

j. combining the second solid phase with a third amphiphilic solvent set to make a third extraction mixture, wherein the weight of the amphiphilic solvent set is about the same as the weight of the second solid phase;

k. separating the third extraction mixture into a third liquid phase comprising neutral lipids and a third solid phase, wherein the first liquid phase has a higher protein concentration than the second and third liquid phases, the second liquid phase has a higher polar lipids concentration than the first and third liquid phases, and the third liquid phase has a higher neutral lipids concentration than the first and second liquid phases;

l. hydrolyzing the neutral lipids into fatty acids and glycerol;

m. hydrogenating and deoxygenating the fatty acids to form a fuel blend stock; and

n. isomerizing the fuel blend stock to form a biofuel.

2. The method of claim 1, further comprising heating at least one of the first, second, or third extraction mixtures to a temperature below the boiling point of the extraction mixture.

3. The method of claim 1, further comprising recovering a first extraction product from the first liquid phase.

4. The method of claim 1, further comprising recovering a second extraction product from the second liquid phase.

5. The method of claim 1, further comprising recovering a third extraction product from the third liquid phase.

6. The method of claim 1, wherein at least one of the first, second or third extraction mixture is held under a pressure greater than or equal to atmospheric pressure for a period of time.

7. The method of claim 6 wherein the period of time is at least 45 minutes.

8. The method of claim 1, wherein at least one of the solvent sets comprises methanol, ethanol, isopropanol, acetone, ethyl acetate, acetonitrile, or any combinations thereof.

9. The method of claim 1, wherein the algal biomass is unfrozen.

10. The method of claim 1, further comprising adjusting the pH of at least one of the extraction mixtures to optimize protein extraction.

11. The method of claim 1 further comprising repeating the sequence of combining and separating steps at least one more time.

12. The method claim 1, wherein at least one of the first, second or third solvent sets comprises two water miscible or two water immiscible solvents.

13. The method of claim 1, wherein at least one of the first, second or third solvent sets comprises one or more water miscible solvents and one or more water immiscible solvents.

14. The method of claim 1, further comprising adjusting the pH of the first extraction mixture to optimize protein extraction.

15. The method of claim 1, wherein the algal biomass is simultaneously at least partially dewatered while products are selectively extracted from the algal biomass.

16. The method of claim 1, further comprising recycling at least one of the first substantially liquid fraction comprising proteins, the second substantially liquid fraction comprising polar lipids, and the third substantially solid biomass fraction comprising carbohydrates into at least one of an animal feed, a human food, and a nutraceutical product.

17. The method of claim 1, further comprising growing the algal cells to produce the neutral lipids by providing carbon dioxide to the algal cells as a carbon source.

18. The method of claim 1, further comprising growing the algal cells to produce the neutral lipids during bioremediation of wastewater by the algal cells.

19. The method of claim 18, wherein the bioremediation is integrated into a wastewater treatment plant.