FLOATING HORIZONTAL TUBULAR PHOTOBIOREACTOR SYSTEM WITH INTEGRATED MANIFOLDS FOR HOUSING PUMPING AND PROCESS MONITORING AND CONTROL DEVICES

Abstract

This invention relates to a floating horizontal tubular photobioreactor system comprising a photosynthetically active area made of flexible tubes connected to rigid manifolds with an integrated system for mixing, aeration and degassing. This invention further relates to methods of using the floating photobioreactor system.

Claims

1. A floating, horizontal tubular photobioreactor system to grow a photosynthetic or mixotrophic microorganism comprising: a photosynthetically active area made of clear tubes; and two manifolds connecting to the ends of the photosynthetically active area.

2. The floating photobioreactor system according to claim 1, wherein the tubes comprise a flexible material.

3. The floating photobioreactor system according to claim 1, wherein the manifolds comprise a rigid material.

4. The floating photobioreactor system according to any one of claims 1 to 3, wherein the photobioreactor is substantially horizontal.

5. The floating photobioreactor system according to any one of claims 1 to 4, further comprising a microorganism solution, which comprises a photosynthetic or mixotrophic microorganism and a growth medium.

6. The floating photobioreactor system according to claim 5, wherein the manifolds contain integrated means to mix, aerate and degas the microorganism solution.

7. The floating photobioreactor system according to claim 6 wherein the manifold contains an integrated means to mix the algae culture

8. The floating photobioreactor system according to claim 7 wherein the means to mix the algae culture is an axial flow pump or other positive displacement pump which can be driven internally or externally from the manifold.

9. The floating photobioreactor system according to claim 6, further comprising a means for introducing gas into the manifolds.

10. The floating photobioreactor system according to claim 9, wherein the means for introducing gas is a perforated hose or a porous stone

11. The floating photobioreactor system according to claim 10, further the location of the aeration introduction being behind the flow of the stirring mechanism

12. The floating photobioreactor system according to claim 6, wherein the manifolds contain an integrated means to degas the culture

13. The floating photobioreactor system according to claim 12, wherein the method to degas the culture is a system which separates the exhaust gas from the remaining algae culture using gravity

14. The floating photobioreactor system according any of the claims 1 to 7, wherein the manifolds are directly connected to the photosynthetically active area without a hose or tube in between.

15. The floating photobioreactor system according to any one of claims 1 to 12, wherein the tubes in the photosynthetically active area are connected to the manifolds via glue, clamps or the like.

16. The floating photobioreactor system according to any of claims 1 to 3, wherein the level of the microorganism solution inside the manifolds are substantially the same as that inside the photosynthetically active area.

17. The floating photobioreactor system according to any of claims 1-14, floating on a supporting water body.

18. The floating photobioreactor system according to any one of claims 1 to 8, wherein the manifolds are connected to a fixed object.

19. The floating photobioreactor system according to claim 18, wherein the fixed object is the ground of the water body, a wall or a surrounding floating structure which could itself be attached to the ground of the water body.

20. The floating photobioreactor system wherein an autonomous culture density estimating system is comprised of light emitting sources passing light through the culture and then capturing the refracted light at sensors which creates a feedback loop for adjusting the operation of the photobioreactor.

21. A method of growing a photosynthetic or mixotrophic organism comprising: (a) introducing a suspension comprising the photosynthetic or mixotrophic organism and growth medium into the floating photobioreactor system of any one of claims 1-20, wherein the photobioreactor is located in a surrounding water body; (b) exposing the suspension to light; and (c) contacting the suspension with a gas mixture comprising CO.sub.2.

22. A method of producing a biomass comprising: (a) growing a photosynthetic or mixotrophic organism in a growth medium in the floating photobioreactor system of any of claims 1-21, wherein the photobioreactor is surrounded by a water body; (b) harvesting the biomass.

23. A method of producing a biofuel comprising: (a) growing a photosynthetic or mixotrophic organism in a growth medium in the floating photobioreactor system of any one of claims 1-22, wherein the photobioreactor is surrounded by a water body; (b) harvesting the organism; and (c) converting one or more selected from the group consisting of lipids, carbohydrates, proteins, vitamins, or antioxidants from the organism, and components of the organism into the biofuel.

24. A method for producing a product comprising: (a) growing a photosynthetic or mixotrophic organism in a growth medium in the floating photobioreactor system of any one of claims 1-23, wherein the photobioreactor is surrounded by a water body; (b) harvesting the organism; and (c) converting one or more selected from the group consisting of lipids, carbohydrates, proteins, vitamins, or antioxidants from the organism and components of the organism into the product, wherein the product is selected from the group consisting of biochemicals, amino acids, fine chemicals, nutriceuticals, pharmaceuticals, energy products, protein, feed for cattle or other species, fish feed, protein source for human nutrition and mineral rich food for human consumption.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0016] FIG. 1 is a three-dimensional view of a floating tubular photobioreactor system with two rigid manifolds integrated on the ends

[0017] FIG. 2 is a cross section of a cutout of a manifold with integrated stirring, aeration, degassing, and process monitoring and control sensors and probes

[0018] FIG. 3 is a cross section of a manifold illustrating the flow of liquid through the de-gassing chamber

DETAILED DESCRIPTION OF THE INVENTION

[0019] In order that the invention herein described may be fully understood, the following detailed description is set forth.

[0020] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as those commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. The materials, methods and examples are illustrative only, and are not intended to be limiting. All publications, patents and other documents mentioned herein are incorporated by reference in their entirety.

[0021] Throughout this specification, the word comprise or variations such as comprises or comprising will be understood to imply the inclusion of a stated integer or groups of integers but not the exclusion of any other integer or group of integers.

[0022] The term a or an may mean more than one of an item.

[0023] The terms and and or may refer to either the conjunctive or disjunctive and mean and/or.

[0024] The term about means within plus or minus 10% of a stated value. For example, about 100 would refer to any number between 90 and 110.

[0025] The term aeration includes the addition of CO.sub.2 and the removal of oxygen at the same time, even if not both functions are always mentioned explicitly.

[0026] The present invention provides a floating horizontal tubular photobioreactor system comprised of a photosynthetically active area made of flexible tubes connected to two rigid manifolds on the ends with an integrated system for mixing, aeration and degassing.

[0027] The present invention introduces two rigid manifolds into the floating horizontal tubular photobioreactor system as a technology enabler that helps provide adequate mixing and aeration to the algae culture, helps the system float, and houses within the system all the essential peripheral equipment, including pumps, aeration and degassing areas, and process monitoring and control sensors and probes. The rigid manifolds provide an integrated solution for mixing, aeration, degassing, and process monitoring and control. In addition, the rigid manifold's height out of the water can be adjusted to increase pressure inside the tubes to the appropriate level.

[0028] The advantages of integrating all functions into rigid manifolds at the ends of the floating, flexible reactor are multiple: [0029] The integrated pump provides an energy-efficient means of mixing the media in the floating low cost reactor. [0030] The integrated pump represents a means to achieve a good mass transfer between gas and liquid phase, especially for CO.sub.2 and oxygen. [0031] By integrating the stirring mechanism into the reactor fewer parts will be required, thus lowering the capital and maintenance costs. [0032] By integrating the manifolds into the reactor the algae suspension does not need to be transported out of and into the reactor, thus saving energy and cost. [0033] The manifolds are built from a rigid material can serve as an anchor to fix the position of the floating flexible reactor.

[0034] The benefits of the algae running through the tubes which make up the photobioreactor are significant: [0035] Instead of uncontrolled expansion under pressure caused by the culture movement, the tubes will expand to their limit and become fully rigid and hold their shape [0036] This rigidity will a) keep the algae culture at the waterline and b) keep the tube fully stretched out along its axis which will keep the ends of the reactor (the manifolds) from coming together [0037] The curvature in the tubes means that there will be more photosynthetically active surface area when combining all the tubes than if the tubes were one piece of plastic film

[0038] These tubes together form one photobioreactor. The tubes are directly connected to the manifolds via direct physical contact which could be using clamps or other restraints.

[0039] Since the tubes are made of very light plastic film, the tube section of the photobioreactor will float in water of salinity greater than or equal to the algae culture. The manifolds will be heavier than water which will require that they be supported through a flotation unit attached to it such as pontoons.

[0040] The tubes and the manifold might have a similar shape at least in one dimension and might be made from different material with even very different characteristics, e.g. flexible material vs. rigid material. The connection between the flexible and rigid part might be created by gluing together the two parts or by using clamps or any other connection.

[0041] The tubes of the photobioreactor and the manifolds might have a different life-time. The connection between them might be constructed in such a way that the part with the shorter life-time, e.g., the tubes, can be replaced easily.

[0042] In order to operate a number of photobioreactors together, being able to autonomously estimate the density of the algae culture in each photobioeactor is important. The present invention accomplishes this via a system of light emitting points which shine light through the algae culture and then sensors which collect the refracted light. Based on the refraction rate, the culture density of the specific algae organism is estimated.

[0043] The photosynthetically active area absorbs sufficient sunlight that if there is not a good heat dispersion mechanism, the temperature inside the photobioreactor reactor rises beyond what is optimal growing conditions. The present invention attaches a heat exchanger made of the same flexible material as the photobioreactor to the photosynthetically active area. This could be attached inside or outside the flexible area, in both the top or bottom sheet. By passing cool water through this heat exchanger, the temperature of the culture inside the reactor will decline.

[0044] The present invention provides methods of growing photosynthetic or mixotrophic organisms. According to the method, a suspension comprising the organism is introduced into one of the floating photobioreactor systems of the present invention. The photobioreactor is located in a surrounding water body. The suspension is exposed to light and brought into contact with a gas mixture comprising CO.sub.2 and other nutrients.

[0045] The present invention also provides methods of producing biomass. According to this method, a suspension comprising the photosynthetic or mixotrophic organisms is introduced into one of the floating photobioreactor systems of the present invention. The photobioreactor is located in a surrounding water body. The organisms are grown in a suspension in the photobioreactor. The suspension is exposed to light and brought into contact with a gas mixture comprising CO.sub.2 and other nutrients. The organisms produce biomass, which is then harvested. The biomass may be harvested by methods known in the art.

[0046] The present invention also provides methods of producing biofuel. According to this method, a suspension comprising the photosynthetic or mixotrophic organisms is introduced into one of the floating photobioreactor systems of the present invention. The photobioreactor is placed (operated in?) in a surrounding water body. The organisms are grown in a suspension in the photobioreactor. The suspension is exposed to light and brought into contact with a gas mixture comprising CO.sub.2 and other nutrients. The organisms produce biomass, which is then harvested. Lipids, carbohydrates, proteins, vitamins, antioxidants, components from the photosynthetic or mixotrophic organism, and other components from the biomass are converted into biofuel. The conversion may be performed by methods known in the art.

[0047] The present invention also provides methods of producing a product selected from the group consisting of biochemicals, amino acids, fine chemicals, nutriceuticals, pharmaceuticals, energy products (ethanol, methane, hydrogen, fatty acids, fats and other lipids, highly energetic compound, propanol, butanol, gasoline-like fuel, diesel-like fuel, alkanes, alkenes, alcohols, organic acids, aromatic compounds), protein, feed for cattle or other species, fish feed, including feed for fish larvae and feed for other potential aquaculture uses, e.g., food for shrimps, crabs, oysters and their larvae, protein source for human nutrition and mineral rich food for human consumption. According to this method, a suspension comprising the photosynthetic or mixotrophic organisms is introduced into one of the floating photobioreactor systems of the present invention. The photobioreactor is operated in a surrounding water body. The organisms are grown in a suspension in the photobioreactor. The suspension is exposed to light and brought into contact with a gas mixture comprising CO.sub.2 and other nutrients. The organisms produce biomass, which is then harvested. Lipids, carbohydrates, proteins, vitamins, antioxidants, components from the photosynthetic or mixotrophic organism, and other components from the biomass are converted into the desired product. The conversion may be performed by methods known in the art.

[0048] While particular materials, formulations, operational sequences, process parameters, and end products have been set forth to describe this invention, they are not intended to be limiting. Rather, it should be noted by those ordinarily skilled in the art that the written disclosures are exemplary only and that various other alternatives, adaptations, and modifications may be made within the scope of the present invention. Accordingly, the present invention is not limited to the specific embodiments illustrated herein.