Method and apparatus for harvesting aquatic plants

• US 5,197,263 A
• Filed: 09/13/1991
• Issued: 03/30/1993
• Est. Priority Date: 09/13/1991
• Status: Expired due to Fees

• Current Assignee: The Lemna Corporation
• Original Assignee: The Lemna Corporation
• Inventors: DeVore, Lawrence J., Midtling, Brian J., Sygen, Victor V.
• Primary Examiner(s): Bagnell, David J.
• Application Number:
  US07/759,488
• Time in Patent Office: 564 Days
• Field of Search: 56/8, 56/9, 210/242.1, 210/242.2, 210/433.1, 210/456, 210/242.3
• US Class Current: 56/8
• CPC Class Codes: A01D 44/00 Harvesting of underwater plants, e.g. harvesting of seaweed

Abstract

A duckweed slurry is recovered from a body of water. The duckweed slurry includes duckweed and water from the body of water. The duckweed slurry is transported to a dewatering station. A majority of the water from the duckweed slurry is removed at the dewatering station. Water removed from the duckweed slurry is returned to the body of water.

Claims

1. A method of harvesting duckweed from a body of water, the method comprising:

recovering a duckweed slurry from the body of water by adjusting a feed head having a mixing chamber, the feed head being proximate the surface of the body of water so duckweed from the surface of the body of water, and water from the body of water flow into the feed head and the mixing chamber, producing the duckweed slurry comprising duckweed and water from the body of water;

transporting the duckweed slurry to a land-based dewatering station;

removing a majority of the water from the duckweed slurry at the dewatering station; and

returning the water removed from the duckweed slurry to the body of water.

2. The method of claim 1 wherein the step of transporting the duckweed slurry comprises:

pumping the duckweed slurry from the feed head to the land-based dewatering station.

3. The method of claim 1 wherein the step of removing a majority of the water from the duckweed slurry comprises:

causing the duckweed slurry to move over a screen so that water from the slurry passes through the screen while substantially all of the duckweed is retained by the screen.

4. The method of claim 3 wherein the step of returning the water comprises:

providing a return flow path, beginning below the screen, so the water that passes through the screen flows along the return flow path to the body of water.

5. The method of claim 1 and further comprising:

removing the duckweed from the dewatering station; and

collecting the duckweed.

6. The method of claim 5 wherein the step of removing the duckweed comprises:

providing a directional chute for directing duckweed removal from the dewatering station and to a collection location.

7. A method of harvesting duckweed from a body of water, the method comprising:

recovering a duckweed slurry, comprising duckweed and water, from the body of water wherein the step of recovering a duckweed slurry comprises;

adjusting a feed head having a mixing chamber, the feed head being proximate the surface of the body of water so duckweed from the surface of the body of water, and water from the body of water flow into the feed head and the mixing chamber;

pumping the duckweed slurry to a land-based dewatering station; and

removing a majority of the water from the duckweed slurry at the land-based dewatering station.

8. The method of claim 7 and further comprising:

returning the water removed from the duckweed slurry to the body of water.

9. The method of claim 7 wherein the step of pumping the duckweed slurry comprises:

pumping the duckweed slurry from the feed head to the land-based dewatering station.

10. The method of claim 7 wherein the step of removing a majority of the water from the duckweed slurry comprises:

causing the duckweed slurry to move over a screen so that water from the slurry passes through the screen while substantially all of the duckweed is retained by the screen.

11. The method of claim 7 and further comprising:

removing the duckweed from the dewatering station; and

collecting the duckweed.

12. The method of claim 11 wherein the step of removing the duckweed comprises:

providing a directional chute for directing duckweed removal from the dewatering station and to a collection location.

13. An apparatus for harvesting duckweed from a pond, comprising:

recovering means for recovering a duckweed slurry from the pond, the duckweed slurry comprising duckweed and water from the pond, the recovering means comprising;

an adjustable feed head having a mixing chamber, the feed head being adjustable to various depths proximate the surface of the pond, and positioned under the surface of the pond so duckweed from the surface of the pond and water from the pond flow into the feed head;

a land-based dewatering station for removing a majority of the water from the duckweed slurry;

pumping means, coupled to the recovering means and the land-based dewatering station, for pumping the duckweed slurry from the recovering means to the dewatering station; and

means for returning the water removed from the duckweed slurry to the pond.

14. The apparatus of claim 13 wherein the mixing chamber includes:

an inlet opening toward the surface of the pond and an outlet coupled to the pumping means; and

wherein the adjustable feed head further comprises;

adjustable means for variably holding the inlet of the mixing chamber a predetermined distance below the surface of the pond.

15. The apparatus of claim 14 wherein the pumping means comprises:

a first hose coupled to the outlet of the mixing chamber and sized to permit passage of the duckweed slurry through the first hose;

a pump, coupled to the first hose, for drawing the duckweed slurry from the outlet of the mixing chamber through the first hose; and

a second hose, coupled to the pump and the land-based dewatering station and sized to permit passage of the duckweed slurry through the second hose, the pump being coupled to pump the duckweed slurry from the mixing chamber through the first hose and to the land-based dewatering station through the second hose.

16. The apparatus of claim 13 wherein the land-based dewatering station comprises:

a screen, coupled to the pumping means so that the duckweed slurry pumped by the pumping means passes over the screen and water from the slurry passes through the screen while substantially all of the duckweed is retained by the screen.

17. The apparatus of claim 16 wherein the land-based dewatering station further comprises:

an input reservoir having an inlet portion coupled to the pumping means for receiving the duckweed slurry, and an outlet portion, the screen being mounted proximate the outlet portion of the input reservoir and tilted downwardly from the outlet portion so that the duckweed slurry exiting the outlet portion of the input reservoir moves along the screen aided by gravitational force; and

an output reservoir below the screen located relative to the screen so that water passing through the screen enters the output reservoir.

18. The apparatus of claim 17 wherein the means for returning the water comprises:

a hose coupled to the output reservoir and providing a return flow path so the water that passes through the screen flows along the return flow path to the pond.

19. The apparatus of claim 13 and further comprising:

means for removing the duckweed from the dewatering station; and

means for collecting the duckweed.

20. The apparatus of claim 19 wherein the means for removing the duckweed comprises:

a directional chute for directing duckweed remaining after water is removed from the duckweed slurry for removal from the land-based dewatering station and to a collection location.

21. A method of harvesting aquatic vegetation from a body of water, the method comprising:

recovering an aquatic vegetation slurry, comprising aquatic vegetation and water, from the body of water wherein the step of recovering an aquatic vegetation slurry comprises;

adjusting a feed head having a mixing chamber, the feed head being proximate the surface of the body of water so aquatic vegetation from the surface of the body of water, and water from the body of water flow into the feed head and the mixing chamber;

pumping the aquatic vegetation slurry to a land-based dewatering station; and

removing a majority of the water from the aquatic vegetation slurry at the land-based dewatering station.

22. The method of claim 21 wherein the step of removing a majority of the water from the aquatic vegetation slurry comprises:

causing the aquatic vegetation slurry to move over a screen so that water from the slurry passes through the screen while substantially all of the aquatic vegetation is retained by the screen.

23. The method of claim 21 and further comprising:

removing the aquatic vegetation from the dewatering station; and

collecting the aquatic vegetation.

24. An apparatus for harvesting aquatic vegetation from a pond, comprising:

recovering means for recovering an aquatic vegetation slurry form the pond, the aquatic vegetation slurry comprising aquatic vegetation and water from the pond, the recovering means comprising;

an adjustable feed head having a mixing chamber, the feed head being adjustable to various depths proximate the surface of the pond, and positioned under the surface of the pond so aquatic vegetation from the surface of the pond and water from the pond flow into the feed head;

a land-based dewatering station for removing a majority of the water from the aquatic vegetation slurry;

pumping means, coupled to the recovering means and the land-based dewatering station, for pumping the aquatic vegetation slurry from the recovering means to the dewatering station; and

means for returning the water removed from the aquatic vegetation slurry to the pond.

25. The apparatus of claim 24 wherein the mixing chamber further includes:

an inlet opening toward the surface of the pond and an outlet coupled to the pumping means; and

wherein the adjustable feed head further comprises;

adjustable means for variably holding the inlet of the mixing chamber a predetermined distance below the surface of the pond.

26. The apparatus of claim 24 wherein the land-based dewatering station comprises:

a screen, coupled to the pumping means so that the aquatic vegetation slurry pumped by the pumping means passes over the screen and water from the slurry passes through the screen while substantially all of the aquatic vegetation is retained by the screen.

27. The apparatus of claim 24 wherein the land-based dewatering station further comprises:

an input reservoir having an inlet portion coupled to the pumping means for receiving the aquatic vegetation slurry, and an outlet portion, the screen being mounted proximate the outlet portion of the input reservoir and tilted downwardly from the outlet portion so that the aquatic vegetation slurry exiting the outlet portion of the input reservoir moves along the screen aided by gravitational force; and

an output reservoir below the screen located relative to the screen so that water passing through the screen enters the output reservoir.

28. The apparatus of claim 24 wherein and further comprising:

means for removing the aquatic vegetation from the dewatering station; and

means for collecting the aquatic vegetation.