Subcritical water extraction of lipids from wet algal biomass
Methods of lipid extraction from biomass, in particular wet algae, through conventionally heated subcritical water, and microwave-assisted subcritical water. In one embodiment, fatty acid methyl esters from solids in a polar phase are further extracted to increase biofuel production.
1. A method of lipid extraction from biomass, the biomass comprising algae and water, the method comprising:
feeding the biomass to a reactor;
pressurizing the biomass in the reactor to a pressure that is above atmospheric pressure;
heating the biomass to heat the water to a subcritical temperature and to lyse the algae in the reactor for a residency time in the reactor sufficient to lyse the algae; and
separating a non-polar phase comprising greater than about 29% total lipid with a FAME content in the total lipid that is greater than about 51% for biofuel production from a polar phase comprising water and solids.
2. The method of claim 1 wherein the heating is conventional heating assisted through microwaves.
3. The method of lipid extraction of claim 2 further comprising centrifuging the biomass before feeding it to the reactor to optimize water content.
4. The method of lipid extraction of claim 2 wherein the biomass has a solids load of between approximately 0.01 dry weight percent and approximately 45 dry weigh percent.
5. The method of lipid extraction of claim 2 wherein the biomass has a solids load of between approximately 5 dry weight percent and approximately 35 dry weigh percent.
6. The method of lipid extraction of claim 2 wherein the biomass has a solids load of between approximately 15 dry weight percent and approximately 30 dry weigh percent.
7. The method of lipid extraction of claim 2 wherein the biomass has a solids load of between approximately 20 dry weight percent and approximately 28 dry weigh percent.
8. The method of lipid extraction of claim 2 further comprising recycling the water.
9. The method of lipid extraction of claim 2 wherein the subcritical temperature in the reactor is between approximately 160° C. and approximately 400° C.
10. The method of lipid extraction of claim 2 wherein the subcritical temperature in the reactor is between approximately 180° C. and approximately 280° C.
11. The method of lipid extraction of claim 2 wherein the subcritical temperature in the reactor is between approximately 195° C. and approximately 230° C.
12. The method of lipid extraction of claim 2 wherein the subcritical temperature in the reactor is between approximately 200° C. and approximately 210° C.
13. The method of lipid extraction of claim 2 wherein the residency time in the reactor is between approximately 1 minute and approximately 60 minutes.
14. The method of lipid extraction of claim 2 wherein the residency time in the reactor is between approximately 10 minutes and approximately 40 minutes.
15. The method of lipid extraction of claim 2 wherein the residency time in the reactor is between approximately 20 minutes and approximately 30 minutes.
16. The method of lipid extraction of claim 2 further comprising agitating the biomass.
17. The method of claim 2 further comprising separating fatty acid methyl esters from the solids in the polar phase.
18. The method of claim 17 wherein the fatty acid methyl esters are separated through pressurizing the biomass in a reactor to a pressure that is above atmospheric pressure and heating the biomass to heat the water to a subcritical temperature and to lyse the algae in the reactor.
19. The method of claim 18 wherein the heating is assisted through microwaves.
20. The method of claim 2 wherein a solvent is used for separating the polar and non-polar phases.
21. The method of claim 20 wherein the solvent is non-polar.
22. The method of claim 20 further comprising reusing the solvent.
23. The method of claim 2 wherein the pressure is between approximately 6 and approximately 221 bar.
24. The method of claim 2 wherein the pressure is between approximately 15 and approximately 83 bar.
25. The method of claim 2 wherein the pressure is between approximately 18 and approximately 26 bar.
26. The method of claim 1 wherein the heating is microwave heating alone.
27. The method of claim 1 further comprising separating fatty acid methyl esters from the solids in the polar phase for biofuel production.
28. The method of lipid extraction of claim 27 further comprising centrifuging the biomass before feeding it to the reactor to optimize water content.
29. The method of lipid extraction of claim 27 wherein the biomass has a solids load of between approximately 0.01 dry weight percent and approximately 40 dry weigh percent.
30. The method of lipid extraction of claim 27 wherein the biomass has a solids load of between approximately 1 dry weight percent and approximately 20 dry weigh percent.
31. The method of lipid extraction of claim 27 wherein the biomass has a solids load of between approximately 5 dry weight percent and approximately 10 dry weigh percent.
32. The method of lipid extraction of claim 27 wherein the water is recycled.
33. The method of lipid extraction of claim 27 wherein the subcritical temperature in the reactor is between approximately 160° C. and approximately 400° C.
34. The method of lipid extraction of claim 27 wherein the subcritical temperature in the reactor is between approximately 200° C. and approximately 300° C.
35. The method of lipid extraction of claim 27 wherein the subcritical temperature in the reactor is between approximately 210° C. and approximately 230° C.
36. The method of lipid extraction of claim 27 wherein the subcritical temperature in the reactor is between approximately 210° C. and approximately 230° C.
37. The method of lipid extraction of claim 27 wherein the residency time in the reactor is between approximately 1 minute and approximately 60 minutes.
38. The method of lipid extraction of claim 27 wherein the residency time in the reactor is between approximately 10 minute and approximately 40 minutes.
39. The method of lipid extraction of claim 27 wherein the residency time in the reactor is between approximately 20 minute and approximately 30 minutes.
40. The method of lipid extraction of claim 27 further comprising agitating the biomass.
41. The method of claim 27 wherein the fatty acid methyl esters are separated through pressurizing the biomass in a reactor to a pressure that is above atmospheric pressure and heating the biomass to heat the water to a subcritical temperature and to lyse the algae in the reactor.
42. The method of claim 41 wherein the heating is assisted through microwaves.
43. The method of claim 27 wherein a solvent is used for separating the polar and non-polar phases.
44. The method of claim 43 wherein the solvent is non-polar.
45. The method of claim 43 further comprising reusing the solvent.
46. The method of claim 27 wherein the pressure is between approximately 6 and approximately 221 bar.
47. The method of claim 27 wherein the pressure is between approximately 15 and approximately 83 bar.
48. The method of claim 27 wherein the pressure is between approximately 18 and approximately 26 bar.