High yield algal biomass production without concentrated CO2 supply under open pond conditions

Patent metadata

Field	Value
Publication number	US-10457909-B2
Application number	US-201715498621-A
Country	US
Kind code	B2
Filing date	Apr 27, 2017
Priority date	Apr 27, 2016
Publication date	Oct 29, 2019
Grant date	Oct 29, 2019

Abstract

Methods and systems for efficient culturing of algae in open ponds. Further, the methods include a method for culturing algae in an open pond medium that is free of any concentrated supply of CO2, and no concentrated source of CO2 is used to supply carbon for culturing the algae. Also, the algae are cultured in the open pond which has a pH above 9.5. In addition, the open pond medium has incorporated therein an inorganic carbon buffer at a specified concentration under conditions for obtaining an increased biomass. Also, the pH above 9.5 permits sufficient increased fixation of atmospheric CO2 into the open pond medium.

First claim

What is claimed is:

1. A method for culturing algae, the method comprising:
culturing alkaliphilic algae in an open pond medium having a pH above 9.5, sufficient to allow increased fixation of atmospheric CO 2 into the open pond medium; and
incorporating into the open pond medium an inorganic carbon buffer, wherein the inorganic carbon buffer comprises HCO 3 − present at a concentration ranging from 4.5 mM to 60 mM and the open pond medium has a salinity in the range of from about 10 g/L to about 30 g/L and an alkalinity of up to about 1 M;
wherein the open pond medium is free of any concentrated supply of CO 2 , and no concentrated source of CO 2 is used to supply carbon for culturing the alkaliphilic algae.

2. The method of claim 1 , wherein the inorganic carbon buffer comprises either a NaHCO 3 /Na 2 CO 3 mixture or a KHCO 3 /K 2 CO 3 mixture.

3. The method of claim 2 , wherein the NaHCO 3 /Na 2 CO 3 mixture or the KHCO 3 /K 2 CO 3 mixture is incorporated into the open pond medium at a concentration ranging from about 7 mM to about 60 mM.

4. The method of claim 1 , wherein the pH of the open pond medium is at least about 9.9.

5. The method of claim 1 , further comprising incorporating glucose or other sugars or carboxylic acids into the open pond medium.

6. The method of claim 1 , wherein the algae comprise a Chlorella sp., Dunaliella sp., Synechocystic sp., Cyanothece sp., Microcoleus sp., Euhalothece sp., or Spirulina sp. strain.

7. The method of claim 1 , further comprising incorporating Ca and/or Mg into the open pond medium at a concentration of less than 7 mg/L.

8. The method of claim 7 , wherein the Ca is incorporated into the open pond medium at a concentration of less than 1.5 mg Ca/L.

9. The method of claim 7 , wherein the Mg is incorporated into the open pond medium at a concentration of less than 0.5 mg Mg/L.

10. The method of claim 1 , further comprising circulating the algae within the open pond medium.

11. The method of claim 1 , further comprising harvesting biomass from the cultured algae and recovering remnant media.

12. The method of claim 11 , further comprising recycling the remnant media in a second open pond medium.

13. The method of claim 11 , further comprising converting the harvested biomass to one or more fuels.

14. The method of claim 13 , wherein the converting comprises hydrothermal liquefaction to produce biocrude having a N content of less than 4%.

15. The method of claim 1 , further comprising regulating nitrogen input in the open pond medium, in a range from about 5 mg/L to about 27 mg/L, so as to modulate the biochemical composition of the algae.

16. The method of claim 1 , wherein the pH of the open pond medium is greater than 10.0.

17. The method of claim 1 , wherein the alkaliphilic algae comprise eukaryotic microalgae.

18. A method for culturing algae, the method comprising:
culturing alkaliphilic algae in an open pond medium having a pH above 9.5, sufficient to allow increased fixation of atmospheric CO 2 into the open pond medium; and
incorporating into the open pond medium an inorganic carbon buffer, wherein the inorganic carbon buffer comprises HCO 3 − present at a concentration ranging from 4.5 mM to 60 mM and the open pond medium has a salinity in the range of from about 10 g/L to about 30 g/L and an alkalinity of up to about 1 M;
wherein the open pond medium is free of any concentrated supply of CO 2 , and no concentrated source of CO 2 is used to supply carbon for culturing the alkaliphilic algae, the method using atmospheric CO 2 alone.

19. A method for culturing an alkaliphilic algal strain, the method comprising:
culturing the alkaliphilic algal strain, the algal strain comprising microalgae or cyanobacteria, in an open pond medium having a pH above 9.5, sufficient to allow increased fixation of atmospheric CO 2 into the open pond medium, and a salinity in the range of from about 10 g/L to about 30 g/L, free of any concentrated supply of CO 2 , and no concentrated source of CO 2 is used to supply carbon for culturing the alkaliphilic algal strain;
incorporating into the open pond medium an inorganic carbon buffer at a total alkalinity ranging from about 3 mM to about 1 M;
regulating nitrogen input in the open pond medium, in a range from about 5 mg/L to about 25 mg/L; and
recovering the cultured algal strain.

Assignees

• Univ Toledo

Inventors

• Pendyala Brahmaiah
• Vadlamani Agasteswar
• Viamajala Sridhar
• Varanasi Sasidhar
• Hanifzadeh Mohammadmatin

Classifications

• C10L2290/04

  Gasification · CPC title

• A01G33/00

  Cultivation of seaweed {or algae} · CPC title

• C10L1/02

  essentially based on components consisting of carbon, hydrogen, and oxygen only · CPC title

• C10L2290/26

  Composting, fermenting or anaerobic digestion fuel components or materials from which fuels are prepared · CPC title

• C12M23/18

  Open ponds; Greenhouse type or underground installations · CPC title