System and Method for Using a Pulse Flow Circulation for Algae Cultivation

• US 20130029403A1
• Filed: 07/25/2011
• Published: 01/31/2013
• Est. Priority Date: 07/25/2011
• Status: Active Grant

• Current Assignee: General Atomics, Inc.
• Original Assignee: General Atomics, Inc.
• Inventors: Hazlebeck, David A., Zhang, Jiping, Wu, Xiaoxi
• Granted Patent: US 8,541,225 B2
• Time in Patent Office: Days
• US Class Current: 435/257.1
• CPC Class Codes: C12M 21/02 Photobioreactors culturing algae A01G33/00, A01H4/001, C12N1/12
• CPC Class Codes: C12M 23/02 Form or structure of the vessel large containers B65D88/00
• CPC Class Codes: C12M 29/12 Pulsatile flow
• CPC Class Codes: C12N 1/12 Unicellular algae; Culture media therefor as new plants A01H13/00

Abstract

A system and method for using a pulse flow to circulate algae in an algae cultivation apparatus are provided. In order to counteract the negative effects of biofouling on algae cultivation equipment, a pulse flow is created to periodically move through an algae cultivation apparatus. The pulse flow will dislodge algae cells adhering to various surfaces of the apparatus, and it will also create turbulence to stir up any algae cells which may have settled onto the bottom of the apparatus. To produce an increased fluid flow rate required to create an effective pulse flow, a sump, which is periodically filled with drawn algal culture from the apparatus, is located at an elevated position above the apparatus. When released, the algal culture travels through a transfer pipe and into the apparatus with gravity causing the algal culture to flow at a very high rate.

Claims

1. A system for using a pulse flow to circulate algae in an algae cultivation apparatus comprises:

an algae cultivation apparatus for growing an algal culture containing a biomass;

a flush tank positioned at an elevation above the algae cultivation apparatus for receiving an effluent of the algal culture to be used to create a pulse flow into the algae cultivation apparatus;

a circulation pump connected to the algae cultivation apparatus, wherein the circulation pump draws the effluent of the algal culture from the algae cultivation apparatus and transfers the effluent to the flush tank via a conduit and wherein the conduit has a first end in contact with the algae cultivation apparatus and a second end connected to the circulation pump; and

an activator, wherein the activator is selectively activated to release the effluent from the flush tank into the conduit to create a pulse flow of effluent through the algae cultivation apparatus.

2. A system as recited in claim 1 further comprising:

a gate valve connected between the flush tank and the algae cultivation apparatus for controlling the release of the effluent from the flush tank to the algae cultivation apparatus; and

a transfer pipe having an inlet and an outlet, wherein the inlet is connected to the flush tank and the outlet is connected to the algae cultivation apparatus.

3. A system as recited in claim 1 wherein the algae cultivation apparatus is a photobioreactor.

4. A system as recited in claim 1 wherein the algae cultivation apparatus is a sloped cultivation pond.

5. A system as recited in claim 4 wherein the cultivation pond includes a device selected from a group comprising a paddle and a circulation pump to keep the algae in continuous motion.

6. A system as recited in claim 1 wherein the activator is a timer, wherein the timer is set to a predetermined time interval used to govern the release of the algal effluent from the flush tank.

7. A system as recited in claim 1 wherein the activator is a level switch, wherein the level switch is activated when the effluent in the flush tank reaches a predetermined level.

8. A system as recited in claim 4 further comprising:

a plurality of flush gates, wherein the area between consecutive flush gates defines a flush segment; and

a main pump for circulating algal culture through the cultivation pond.

9. A system as recited in claim 8 wherein the plurality of flush gates are opened simultaneously.

10. A system as recited in claim 8 wherein the plurality of flush gates are opened sequentially.

11. A system as recited in claim 1 further comprising:

a gas exchange tank in fluid communication with the algae cultivation apparatus for receiving a portion of the effluent from the algae cultivation apparatus, wherein the gas exchange tank enriches the effluent with CO₂;

a diverting valve connected between the gas exchange tank and the algae cultivation apparatus, wherein the diverting valve controls the flow of effluent from the algae cultivation apparatus to the gas exchange tank; and

a return pipe connected between the gas exchange tank and the algae cultivation apparatus for returning the CO₂-enriched effluent back to the algae cultivation apparatus.

12. A method for using a pulse flow to circulate algae in an algae cultivation apparatus which comprises the steps of:

cultivating an algal culture in an algae cultivation apparatus;

circulating the algal culture using the algae cultivation apparatus;

transferring a portion of algal culture to a flush tank using a circulation pump, wherein the portion of algal culture being transferred is an effluent; and

flushing the effluent from the flush tank into the algae cultivation apparatus by initiating an activator to allow for gravity flow of the effluent from the flush tank into the algae cultivation apparatus via a transfer pipe having a first end and a second end, wherein the first end of the transfer pipe connects to the flush tank and the second end of the transfer pipe is positioned in the algae cultivation apparatus.

13. A method as recited in claim 12 wherein the activator comprises a device selected from a group comprising a timer and a level switch, wherein the device is connected to the flush tank, to open a gate valve to allow the effluent to enter the transfer pipe.

14. A method as recited in claim 12 wherein the cultivating step is accomplished using a sloped pond, wherein the sloped pond is constructed with a plurality of flush gates.

15. A method as recited in claim 14 further comprising the step of activating the flush gates in sequence.

16. A method as recited in claim 14 further comprising the step of activating the plurality of flush gates simultaneously.

17. A system for using a pulse flow to circulate algae in an algae cultivation system which comprises:

a cultivation pond for cultivating an algal culture;

a main pump for circulating the algal culture through the cultivation pond;

a sump, wherein the sump is used to store the algal culture, wherein the algal culture is forcibly released from the sump to create a pulse flow of algal culture through the cultivation pond; and

an activator for initiating the release of the algal culture from the surnp to the sloped pond.

18. A system as recited in claim 17 wherein the sloped pond is constructed with a plurality of flush gates, wherein the area between the flush gates is a flush segment, and wherein the pulse flow travels one segment at a time when the flush gates are opened in sequential order.

19. A system as recited in claim 18 wherein the activator comprises a timer, wherein the timer is electrically connected to each flush gate to control the opening of each flush gate according to a predetermined time interval.

20. A system as recited in claim 18 wherein the activator comprises a level switch to measure the amount of algal culture in the sump, wherein the level switch can initiate the release of algal culture from the flush tank when the amount of algal culture reaches a predetermined level in the flush tank.