Photobioreactor

• US 9,738,868 B2
• Filed: 07/04/2012
• Issued: 08/22/2017
• Est. Priority Date: 07/19/2011
• Status: Active Grant

• Current Assignee: National Research Council Canada
• Original Assignee: National Research Council Canada
• Inventors: Bensebaa, Farid
• Primary Examiner(s): Hobbs, Michael
• Application Number:
  US14/232,006
• Publication Number:
  US 20140170726A1
• Time in Patent Office: 1,875 Days
• Field of Search: 4352921, 47 14
• CPC Class Codes: C12M 21/02 Photobioreactors culturing algae A01G33/00, A01H4/001, C12N1/12
• CPC Class Codes: C12M 23/06 Tubular C12M23/08, C12M23/16 take precedence
• CPC Class Codes: C12M 23/20 Material Coatings immunocoatings C12M25/00
• CPC Class Codes: C12M 23/22 Transparent or translucent parts glassware for laboratory use B01L3/00
• CPC Class Codes: C12M 33/00 Means for introduction, transport, positioning, extraction, harvesting, peeling or sampling of biological material in or from the apparatus chemical or physical laboratory apparatus in general B01L, devices for taking cell samples A61B10/0045, withdrawing or distributing predetermined quantities of fluid B01L99/00
• CPC Class Codes: C12M 47/02 Separating microorganisms from the culture medium; Concentration of biomass separating microorganisms from their culture media C12N1/02
• CPC Class Codes: C12N 1/12 Unicellular algae; Culture media therefor as new plants A01H13/00

Abstract

In the present invention, a photobioreactor and process for producing and harvesting microalgae involves a vessel for cultivating microalgae that is at least partially transparent to admit light into the vessel. At least a portion of the transparent part of the vessel is coated with a transparent conductive oxide (TCO) layer. The TCO layer is transparent to visible light necessary for algae growth, but is opaque to infrared light thereby reducing thermal heating load in the photobioreactor. The TCO layer also acts as an electrode, which when combined with a counter-electrode can provide a potential difference across at least a portion of the interior of the vessel between the TCO layer and the counter-electrode. The electrode arrangement can be utilized in an electrochemical process (e.g. electrodeposition and/or electroflotation) to dewater and harvest the microalgae in the same apparatus as the microalgae was cultivated.

Claims

1. A photobioreactor for producing and harvesting microalgae, the photobioreactor comprising:

a vessel for cultivating microalgae, the vessel having at least one wall and an interior, at least a portion of the at least one wall being transparent to permit light of a frequency necessary to promote microalgae growth to enter into the interior of the vessel, an electrode consisting of at least part of the transparent portion of the at least one wall, said electrode comprising a layer of transparent conductive oxide selected from the group consisting of indium doped tin oxide, fluorine doped tin oxide, antimony doped tin oxide, zinc doped tin oxide, aluminum doped zinc oxide and a mixture thereof, the layer of transparent conducting oxide being transparent to light of the frequency necessary to promote microalgae growth and opaque to light of an infrared frequency range; and

,

a counter-electrode within the interior of the vessel, the counter-electrode being electrically connected to the layer of transparent conductive oxide for providing a potential difference across at least a portion of the interior of the vessel between the layer of transparent conductive oxide and the counter-electrode, with the proviso that the counter electrode is not a coating on a wall of the vessel.

2. The photobioreactor according to claim 1, wherein the counter-electrode comprises a metal, a conductive carbon, a transparent conducting oxide or a mixture thereof.

3. The photobioreactor according to claim 1, wherein the counter-electrode comprises aluminum, stainless steel or a transparent conducting oxide.

4. The photobioreactor according to claim 1, wherein the counter-electrode is an anode.

5. The photobioreactor according to claim 1 which is a tubular photobioreactor, wherein the vessel is cylindrical and the layer of transparent conducting oxide is coated on a curved surface of the cylindrical vessel.

6. The photobioreactor according to claim 1, wherein the vessel comprises glass, plastic, fiberglass or mixture thereof.

7. The photobioreactor according to claim 1, wherein the layer of transparent conductive oxide for use as an electrode is oriented vertically or horizontally and the counter-electrode is oriented vertically or horizontally.

8. The photobioreactor of claim 1 wherein the layer of transparent conductive oxide is applied at a thickness from about 0.01 μ

m to about 100 μ

m to said at least part of the transparent portion of the at least one wall.

9. The photobioreactor according to claim 1, wherein the counter-electrode comprises an inert coating.

10. The photobioreactor according to claim 1, wherein the counter-electrode is moveable.

11. The photobioreactor according to claim 1, which further comprises an electrical power source that is external of the interior of the vessel and that is electrically connected to the layer of transparent conductive oxide and to the counter electrode for providing a potential difference across at least a portion of the interior of the vessel between the layer of transparent conductive oxide and the counter-electrode.

17. A method for producing and harvesting microalgae, the method comprising providing the photobioreactor of claim 1, introducing a cell culture medium and microalgae within the photobioreactor, growing the microalgae within the cell culture medium, and dewatering the microalgae electrochemically by applying a potential difference across at least a portion of the interior of the vessel of the photobioreactor between the layer of transparent conductive oxide and the counter-electrode.

18. The method according to claim 17, wherein applying the potential difference results in one electrode being a cathode and the other being an anode, and dewatering is accomplished by electroflotation in which the microalgae are floated to a surface of the cell culture medium by formation of gas bubbles at the anode due to electrolysis of water.

19. The method according to claim 17, wherein the dewatered microalgae is collected mechanically or chemically.

12. A photobioreactor for producing and harvesting microalgae, the photobioreactor comprising:

a vessel for cultivating microalgae, the vessel having at least one wall and an interior, at least a portion of the at least one wall being transparent to permit light of a frequency necessary to promote microalgae growth to enter into the interior of the vessel, an electrode consisting of at least part of the transparent portion of the at least one wall, said electrode comprising a layer of transparent conductive oxide selected from the group consisting of indium doped tin oxide, fluorine doped tin oxide, antimony doped tin oxide, zinc doped tin oxide, aluminum doped zinc oxide and a mixture thereof, the layer of transparent conducting oxide being transparent to light of the frequency necessary to promote microalgae growth and opaque to light of an infrared frequency range;

a counter-electrode; and

an electrical power source that is external of the interior of the vessel and that is electrically connected to the layer of transparent conductive oxide and to the counter electrode for providing a potential difference across at least a portion of the interior of the vessel between the layer of transparent conductive oxide and the counter-electrode.

13. The photobioreactor according to claim 12 which is a flat plate photobioreactor, wherein the vessel comprises a transparent first outer wall having the layer of transparent conductive oxide coated thereon and an opposed second outer wall having, the counter-electrode coated thereon.

14. The photobioreactor according to claim 13, wherein the counter-electrode is a layer of transparent conducting oxide coated on the second outer wall and the second outer wall is transparent.

15. The photobioreactor according to claim 12, wherein the counter-electrode comprises a metal, a conductive carbon, a transparent conducting oxide or a mixture thereof.

16. The photobioreactor according to claim 12, wherein the counter-electrode comprises aluminum, stainless steel or a transparent conducting oxide.