U.S. patent application number 13/752853 was filed with the patent office on 2013-09-12 for v-trough photobioreactor system and method of use.
This patent application is currently assigned to HELIAE DEVELOPMENT, LLC. The applicant listed for this patent is HELIAE DEVELOPMENT, LLC. Invention is credited to Jason D. LICAMELE, Carl L. WHITE.
Application Number | 20130232866 13/752853 |
Document ID | / |
Family ID | 44814573 |
Filed Date | 2013-09-12 |
United States Patent
Application |
20130232866 |
Kind Code |
A1 |
LICAMELE; Jason D. ; et
al. |
September 12, 2013 |
V-Trough Photobioreactor System and Method of Use
Abstract
Disclosed herein are photobioreactor systems for high
productivity aquaculture or aquafarming for growing of algae or
other organisms in an aquatic environment featuring aspects that
favor improved growth rates by achieving control over the contents
of the growth medium, including carbon source, nitrogen source, and
essential trace elements necessary for growth.
Inventors: |
LICAMELE; Jason D.;
(Scottsdale, AZ) ; WHITE; Carl L.; (Gilbert,
AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HELIAE DEVELOPMENT, LLC |
Gilbert |
AZ |
US |
|
|
Assignee: |
HELIAE DEVELOPMENT, LLC
Gilbert
AZ
|
Family ID: |
44814573 |
Appl. No.: |
13/752853 |
Filed: |
January 29, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13149463 |
May 31, 2011 |
8365462 |
|
|
13752853 |
|
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|
Current U.S.
Class: |
47/1.4 |
Current CPC
Class: |
C12M 21/02 20130101;
C12M 23/34 20130101; C12M 31/02 20130101; Y02A 40/80 20180101; C12M
29/00 20130101; A01G 33/00 20130101; C12M 29/24 20130101; C12M
23/02 20130101; C12M 27/00 20130101; C12M 31/10 20130101; Y02A
40/88 20180101 |
Class at
Publication: |
47/1.4 |
International
Class: |
A01G 33/00 20060101
A01G033/00 |
Claims
1. A photobioreactor, comprising: a) a cavity defined by: i) a
substantially V-shaped base comprising two base walls, said base
walls meeting proximate to an axis defining an interior angle, each
base wall comprising: 1) a sloped portion and a substantially
vertical portion; 2) a proximal end and a distal end; and 3) a
length extending along said axis and a width extending
perpendicular to said axis; ii) a proximal side wall adjacent to
said proximal end; and iii) a distal side wall adjacent to said
distal end; b) at least one gas delivery system disposed within
said cavity and extending parallel to said axis; and c) at least
one carbon dioxide delivery system disposed within said cavity and
extending parallel to said axis.
2. The photobioreactor of claim 1, wherein said base walls comprise
a curved transition between said sloped portion and said
substantially vertical portion.
3. The photobioreactor of claim 1, further comprising a liner
disposed within said cavity.
4. The photobioreactor of claim 1, wherein said interior angle is
between about 60 and about 140 degrees.
5. The photobioreactor of claim 1, further comprising a harvesting
aperture through at least a portion of said proximal side wall.
6. The photobioreactor of claim 1, further comprising a nutrient
injection system.
7. The photobioreactor of claim 1, wherein said gas delivery system
comprises a line comprising a plurality of disposed orifices along
its length to provide congruent pressure for even gas
dispersion.
8. The photobioreactor of claim 1, wherein said gas delivery system
comprises a line comprising a plurality of orifices disposed along
its length, said orifices comprising a major dimension ranging
between about 1 mm and about 5 mm.
9. The photobioreactor of claim 1, wherein said carbon dioxide
delivery system comprises a line comprising a plurality of orifices
disposed along its length, said orifices comprising a major
dimension ranging between about 0.001 microns and about 1 mm.
10. The photobioreactor of claim 1, further comprising a slope from
said proximal end to said distal end.
11. The photobioreactor of claim 1, further comprising a cover.
12. The photobioreactor of claim 1, further comprising a support
structure, wherein at least a portion of said base walls and/or
said side wall are disposed on top of said support structure.
13. The photobioreactor of claim 1, further comprising a culture
medium comprising biomaterials disposed within said cavity.
14. The photobioreactor of claim 7, wherein said orifices comprise
at least one of perforations, pores, injection points, or
apertures.
15. The photobioreactor of claim 8, wherein said orifices comprise
at least one of perforations, pores, injection points, or
apertures.
16. The photobioreactor of claim 9, wherein said orifices comprise
at least one of perforations, pores, injection points, or
apertures.
17. The photobioreactor of claim 11, said cover further comprising
a glazing material fabricated from a material selected from the
group consisting of polyethylene, lexan, polycarbonate, clear
vinyl, clear polyvinyl chloride, glass, or a combination
thereof.
18. The photobioreactor of claim 12, wherein said support structure
comprises HDPE.
19. The photobioreactor of claim 12, wherein said support structure
comprises foam.
20. The photobioreactor of claim 12, wherein said support structure
is capable of disassembly and stacking.
21. The photobioreactor of claim 12, further comprising foam
insulation disposed adjacent to at least a portion of said base
walls and/or said side walls on a side opposite said cavity.
22. The photobioreactor of claim 12, wherein said support structure
is installed in the ground.
23. The photobioreactor of claim 13, wherein said culture medium
has a stable pH.
24. The photobioreactor of claim 13, wherein said biomaterials are
harvested from said culture medium via a gravity line.
25. The photobioreactor of claim 13, wherein a flow of gas exiting
said gas delivery system provides for a mixing rate of said culture
medium.
26. The photobioreactor of claim 13, wherein said culture medium is
driven from said proximal end to said distal end.
27. The photobioreactor of claim 13, wherein said gas and carbon
dioxide delivery systems are used in conjunction with pH buffers
for stabilizing the pH of said culture medium.
28. The photobioreactor of claim 21, wherein said foam insulation
comprises said support structure.
29. The photobioreactor of claim 25, further comprising a slope
from said proximal end to said distal end, wherein said slope and
said mixing rate drive said culture medium in a direction from said
proximal end to said distal end.
30. A kit for assembling a photobioreactor, comprising: a) two base
walls; b) a proximal side wall; c) a distal side wall; and d) a
first liner capable of being folded, collapsed, or rolled up;
which, when assembled into a photobioreactor, comprises a cavity
defined by: i) a substantially V-shaped base comprising said base
walls, said base walls meeting proximate to an axis defining an
interior angle, each base wall comprising: 1) a sloped portion and
a substantially vertical portion; 2) a proximal end and a distal
end; and 3) a length extending along said axis and a width
extending perpendicular to said axis; ii) said proximal side wall,
disposed adjacent to said proximal end; and iii) said distal side
wall, disposed adjacent to said distal end.
31. The kit of claim 30, wherein said base walls and side walls
comprise foam blocks.
32. The kit of claim 30, further comprising a second liner which,
when assembled, at least partially contains said base walls and
said side walls.
33. The kit of claim 31, wherein said first and said second liners
are folded, collapsed, or rolled up, and said support structure is
disassembled.
34. The kit of claim 31, wherein said first and said second liners
are secured to one another.
35. A method of producing a biomass comprising: a) dispensing a
biomass culture medium in a photobioreactor, the photobioreactor
comprising: i) a cavity defined by: 1) a substantially V-shaped
base comprising two base walls, said base walls meeting proximate
to an axis defining an interior angle, each base wall comprising:
A) a sloped portion and a substantially vertical portion; B) a
proximal end and a distal end; and C) a length extending along said
axis and a width extending perpendicular to said axis; 2) a
proximal side wall adjacent to said proximal end; 3) a distal side
wall adjacent to said distal end; ii) at least one gas delivery
system disposed within said cavity and extending parallel to said
axis; and iii) at least one carbon dioxide delivery system disposed
within said cavity and extending parallel to said axis. b)
supplying a gas through said gas delivery system, producing bubbles
having diameters between about 1 and about 3 mm; and c) supplying
carbon dioxide through said carbon dioxide delivery system,
producing bubbles having diameters between about 0.001 and about
500 microns.
36. The method of claim 35, wherein solids are substantially
prevented from settling by flow of gas exiting said gas delivery
system.
37. The method of claim 35, further comprising operating an ozone
sensor and control system such that ozone levels in said culture
medium are maintained between about 0.5 and about 1 mg/mL.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of and claims the benefit
of priority of U.S. patent application Ser. No. 13/149,463, filed
May 31, 2011, now U.S. Pat. No. 8,365,462, and is related to U.S.
patent application Ser. No. 13/249,426, filed Sep. 30, 2011, now
U.S. Pat. No. 8,341,877, and International Patent Application No.
PCT/US2012/040157, filed May 31, 2012, published as International
Patent Application Publication No. WO 2012/166883 on Dec. 6, 2012,
the entire disclosures of which are incorporated by reference
herein.
FIELD OF THE INVENTION
[0002] Disclosed herein are photobioreactor systems for high
productivity aquaculture or aquafarming for growing of algae or
other organisms in an aquatic environment featuring aspects that
favor improved growth rates by achieving efficient mixing rates,
control over the contents of the growth medium, including carbon
source, nitrogen source, and essential trace elements necessary for
growth.
BACKGROUND
[0003] Algae have gained significant importance in recent years
given their advantage in solving several critical global issues
such as the production of renewable fuels and animal feedstock,
reducing global climate change via carbon dioxide remediation,
wastewater treatment, and sustainability. Algae farming is also
used for the production of food, feed, nutraceuticals, chemicals,
biofuels, pharmaceuticals, and other products that can be extracted
from algae.
[0004] Algae's superiority as a biofuel feedstock arises from a
number of factors such as high per-acre productivity when compared
to typical terrestrial oil crop plants, non-food based feedstock
resources, and its ability to be cultivated on otherwise
non-productive, non-arable land.
[0005] Several thousand species of algae have been screened and
studied for lipid production worldwide over the past several
decades, of which about 300 species rich in lipid production have
been identified. The lipids produced by algae are similar in
composition when compared to other contemporary oil sources such as
oil seeds, cereals, and nuts.
[0006] As the United States has already consumed over 80% of its
proven oil reserves, it currently imports more than 60% of its oil.
It is anticipated that within 20 years the United States will be
importing in the range of 80-90% of its oil. Much of this imported
oil is supplied by nations in politically volatile regions of the
world, a fact which poses a constant threat to a stable oil supply
for the United States. Although the United States can continue to
increasingly import foreign oil, global oil supplies are not
infinite and importation continues to increase the United States
trade deficit and create an increasing burden on the economy.
[0007] Commercial cultivation of lipid-producing algae provides a
solution to the growing problem of oil shortages and increases in
cost of importation. Algae oil can be used to replace
petroleum-based products. Algae can be used to generate oil of
varying lipid profiles for use in a variety of applications,
including, but not limited to, the generation of diesel, gasoline,
kerosene, and jet fuel.
[0008] Algae farming typically uses photobioreactors (PBRs), such
as flat panel PBRs and tubular PBRs, which are small in volume in
order to improve the amount of light utilized by the algae. These
devices have high productivity, but not high enough to make up for
the loss in volume. Other PBR systems, such as ponds, raceways or
troughs are used to provide larger scale production, but these
systems suffer from low productivity. Current PBR systems are
typically designed with flat bottoms where solids settle out, and
over time potentially lead to bacterial and fungal growth. Such
unwanted growth potentially decreases the productivity and growth
of algae. Additionally, pond systems are large systems (half acre,
acre, or hectare size) with minimal mixing. Mixing in these systems
is often accomplished by way of paddle wheels or air lines, which
are not optimal for algae growth, and do not develop a systematic
pattern of mixing within the system to keep solids from settling
out. Optimal mixing of such systems require large amounts of
energy, reducing overall cost efficiency. Pond or raceway systems
also require maintenance such as draining, harvesting, and cleaning
to maintain optimal productivity levels for algae growth. This
results in downtime of the system, labor to clean, and large
amounts of water to refill these systems.
[0009] The present disclosure provides V-shaped PBR systems
designed for optimal productivity at large volumes in order to
deliver a high yield per acre. These systems produces large volumes
of algae in a highly productive and cost efficient manner.
BRIEF SUMMARY OF THE INVENTION
[0010] In one aspect, a photobioreactor is disclosed which
comprises a cavity defined by: a substantially V-shaped base
comprising: two base walls, said base walls meeting proximate to an
axis defining an interior angle, each base wall comprising: a
sloped portion and a substantially vertical portion, a proximal end
and a distal end, and a length extending along said axis and a
width extending perpendicular to said axis; the cavity being
further defined by: a proximal side wall adjacent to said proximal
end, and a distal side wall adjacent to said distal end; and the
photobioreactor system further comprising: at least one gas
delivery system disposed within said cavity and extending parallel
to said axis, and at least one carbon dioxide delivery system
disposed within said cavity and extending parallel to said
axis.
[0011] In another aspect, a kit for assembling a photobioreactor is
disclosed which comprises two base walls, a proximal side wall, a
distal side wall and a first liner capable of being folded,
collapsed, or rolled up, which, when assembled into a
photobioreactor, comprises a cavity defined by: a substantially
V-shaped base comprising: said base walls, said base walls meeting
proximate to an axis defining an interior angle, each base wall
comprising: a sloped portion and a substantially vertical portion,
a proximal end and a distal end, and a length extending along said
axis and a width extending perpendicular to said axis; and the
cavity being further defined by: said proximal side wall, disposed
adjacent to said proximal end, and said distal side wall, disposed
adjacent to said distal end.
[0012] In another aspect, a method of producing a biomass is
disclosed which comprises dispensing a biomass culture medium in a
photobioreactor, the photobioreactor comprising: a cavity defined
by: a substantially V-shaped base comprising: two base walls, said
base walls meeting proximate to an axis defining an interior angle,
each base wall comprising: a sloped portion and a substantially
vertical portion, a proximal end and a distal end, and a length
extending along said axis and a width extending perpendicular to
said axis; the cavity being further defined by: a proximal side
wall adjacent to said proximal end, and a distal side wall adjacent
to said distal end; the photobioreactor system further comprising:
at least one gas delivery system disposed within said cavity and
extending parallel to said axis, and at least one carbon dioxide
delivery system disposed within said cavity and extending parallel
to said axis; and the method further comprising supplying a gas
through said gas delivery system, producing bubbles having
diameters between about 1 and about 3 mm, and supplying carbon
dioxide through said carbon dioxide delivery system, producing
bubbles having diameters between about 0.001 and about 500
microns.
[0013] The V-trough PBR systems disclosed herein concentrate
settleable material at an axis, and apply gas at the same point for
mixing and keeping materials and algae in suspension. This system
of agitation also serves to bring algae to the surface, where light
penetration may be focused for increased productivity. The
geometric shape of the V defines the axis where solids would
otherwise concentrate. These V-trough PBR systems are more
efficient and require less energy for mixing because the culture
medium is concentrated along the axis at the bottom of the V,
creating a specific location where application of agitation is most
efficient. This allows the system to be run in a semi-continuous or
continuous mode, which decreases downtime, labor and energy that
would otherwise be required to keep the system running efficiently,
and thus resulting in improved total annual productivity.
Glossary
[0014] As used herein, the term "productivity" refers to a standing
biomass concentration for a batch harvest, or the daily biomass
generated per given volume for a semi-continuously or continuously
operated PBR. Productivity is a function of the amount of light,
carbon dioxide, and nutrients that the biomaterials receive.
[0015] As used herein, the term "light" generally refers to
photosynthetically active radiation (PAR). This can come in the
form of unseparated wavelengths of light (such as sunlight), or
selected wavelengths of light. Light can be natural or supplied by
other means, such as light emitting diodes (LEDs).
BRIEF DESCRIPTION OF THE FIGURES
[0016] Like numerals indicate like features in the Figures included
herein.
[0017] FIG. 1 shows a perspective view schematic of an illustrative
embodiment of the V-trough PBR systems disclosed herein.
[0018] FIG. 2 shows a bird's eye view of an additional illustrative
embodiment of the V-trough PBR systems disclosed herein.
[0019] FIG. 3 shows an end-on view of the proximal side wall of an
illustrative embodiment of the V-trough PBR systems disclosed
herein.
[0020] FIG. 4 shows an end-on view of the distal side wall of an
illustrative embodiment of the V-trough PBR systems disclosed
herein.
[0021] FIG. 5 shows a flowchart of an illustrative embodiment of
the method for growing a biomass using the V-trough PBR systems
disclosed herein.
[0022] FIG. 6 shows an end-on view of the proximal side wall of an
illustrative embodiment of the V-trough PBR systems disclosed
herein.
[0023] FIG. 7 shows an exploded aspected view of an illustrative
embodiment of the V-trough PBR systems disclosed herein, where the
system is disassembled.
DETAILED DESCRIPTION
[0024] In one aspect, a photobioreactor is disclosed which
comprises a cavity defined by: a substantially V-shaped base
comprising: two base walls, said base walls meeting proximate to an
axis defining an interior angle, each base wall comprising: a
sloped portion and a substantially vertical portion, a proximal end
and a distal end, and a length extending along said axis and a
width extending perpendicular to said axis; the cavity being
further defined by: a proximal side wall adjacent to said proximal
end, and a distal side wall adjacent to said distal end; and the
photobioreactor system further comprising: at least one gas
delivery system disposed within said cavity and extending parallel
to said axis, and at least one carbon dioxide delivery system
disposed within said cavity and extending parallel to said
axis.
[0025] In another aspect, a kit for assembling a photobioreactor is
disclosed which comprises two base walls, a proximal side wall, a
distal side wall and a first liner capable of being folded,
collapsed, or rolled up, which, when assembled into a
photobioreactor, comprises a cavity defined by: a substantially
V-shaped base comprising: said base walls, said base walls meeting
proximate to an axis defining an interior angle, each base wall
comprising: a sloped portion and a substantially vertical portion,
a proximal end and a distal end, and a length extending along said
axis and a width extending perpendicular to said axis; and the
cavity being further defined by: said proximal side wall, disposed
adjacent to said proximal end, and said distal side wall, disposed
adjacent to said distal end.
[0026] In another aspect, a method of producing a biomass is
disclosed which comprises dispensing a biomass culture medium in a
photobioreactor, the photobioreactor comprising: a cavity defined
by: a substantially V-shaped base comprising: two base walls, said
base walls meeting proximate to an axis defining an interior angle,
each base wall comprising: a sloped portion and a substantially
vertical portion, a proximal end and a distal end, and a length
extending along said axis and a width extending perpendicular to
said axis; the cavity being further defined by: a proximal side
wall adjacent to said proximal end, and a distal side wall adjacent
to said distal end; the photobioreactor system further comprising:
at least one gas delivery system disposed within said cavity and
extending parallel to said axis, and at least one carbon dioxide
delivery system disposed within said cavity and extending parallel
to said axis; and the method further comprising supplying a gas
through said gas delivery system, producing bubbles having
diameters between about 1 and about 3 mm, and supplying carbon
dioxide through said carbon dioxide delivery system, producing
bubbles having diameters between about 0.001 and about 500
microns.
Shape of the V-Trough
[0027] The V-shaped base of the V-trough PBR systems disclosed
herein comprises an inner dimension that tapers substantially to a
V at the bottom. In some embodiments, the bottom of the trough is a
point (i.e. meeting of two flat elements). In further embodiments,
the bottom of the trough is rounded. This property results in
reduced dead space as compared to a flat-bottomed tank, allows for
increased mixing rate of the culture medium, improved turnover of
the medium and biomass within the PBRs and overall high volume,
high productivity PBR systems. Absent this V-shaped base, the
propensity of solids to settle at the bottom of the PBR is
increased.
[0028] The V-shaped base defines an interior angle less than about
180.degree. and more than about 45.degree.. In some embodiments,
the angle is between about 34.degree. and about 140.degree.. In
some embodiments, the angle is between about 60.degree. and about
140.degree.. In some embodiments, the angle is between about
34.degree. and about 120.degree.. In some embodiments, the angle is
between about 60.degree. and about 120.degree.. In some
embodiments, the angle is between about 80.degree. and about
112.degree.. In some embodiments, the angle is between about
800.degree. and about 100.degree.. The angle depends on light
source, geographic location of the PBR, the targeted biological
materials, standing biomaterial concentration, and desired
productivity. As the angle decreases, the total volume of the PBR
decreases, assuming all other dimensions are held constant. The
substantially vertical portions of the base walls can extend
vertically to compensate for loss in volume as the angle
decreases.
[0029] Side walls extend upward from the V-shaped base to increase
the total volume of the PBR. As the side walls extend, the volume
of the PBR increases while maintaining the same footprint, given
that all other dimensions are held constant. In some embodiments,
the side walls extend vertically upwards. In some embodiments, the
side walls extend upwards at an angle. In some embodiments, the
side walls range in thickness from between about 2 to about 10
inches. In further embodiments, the side walls range in thickness
from between about 4 to about 6 inches. In some embodiments, the
side walls are straight. In further embodiments, the side walls are
curved. In some embodiments, the side walls and V-shaped base curve
such that they form a single wall, with no discernible separation.
In some embodiments, the cavity is a single formed unit.
[0030] The desired length and volume of the V-trough PBR systems
disclosed herein is determined by the efficiency of heating and/or
cooling capacity, and retention time of the biomaterials. The
volumes of the systems are designed to harvest biomaterials before
growth and productivity drop off as a function of cell longevity
and cell vigor. Cell longevity and cell vigor is a function of the
nature of the biomaterials, contamination in the culture,
environmental parameters applied to the culture, and water
chemistry parameters. In some embodiments, the V-trough PBR system
is between about 15 feet and about 100 feet long. In further
embodiments, the system is over 100 feet long.
[0031] The volume of the V-trough PBR systems disclosed herein are
determined by a number of factors, including the angle of the
V-shaped base, the dimensions of the side walls, and the overall
length and width of the V-trough. Generally, for light-dependent
biomaterials, productivity is increased as the volume of the PBR
system decreases, due to increased mixing and exposure of the
biomaterials to light. The V-trough is designed to mitigate the
loss in productivity that occurs when the volume of a vessel is
increased. The surface area to volume ratio of the V-trough is such
that the biomaterials have a greater exposure to light, as
biomaterials circulating through the PBR system will receive
differing amounts of light depending on whether they are proximate
to an illuminated surface or distal from it (in a "dark zone")
during circulation.
[0032] The reduction of settleable solids in the V-trough PBR
systems disclosed herein provides a significant advantage over
existing devices. First, the systems disclosed herein can be run in
a continuous or semi-continuous mode, while existing devices
require downtime and maintenance costs to remove settled solids.
Further, because the system does not need to be stopped
periodically, or with the frequency of existing systems, the
biomass shows an improved probability of surviving at the desired
productivity for a longer period of time than existing devices.
Gas Delivery System
[0033] The gas delivery systems of the V-trough PBR systems
disclosed herein can be used, inter alia, for efficient mixing of
the culture medium. The gas delivery systems are placed
strategically along or near the axis defined by the bottom of the V
to keep solids in suspension, and to provide improved mixing of the
culture medium. Mixing rate of the culture medium can be controlled
by the gas delivery system alone, or in combination with other
agitation means. Control of mixing rate and retention time of the
culture medium is important so that these parameters can be varied
depending on the concentration of the medium. Rate of gas
injection, combined with the V-shaped design drives the mixing
efficiency of the system. Generally, for light-dependent
biomaterials, a higher rate of mixing is desired to increase the
amount of biomaterials coming into contact with the light,
resulting in greater productivity. In some embodiments, the gas
comprises air. In further embodiments, the gas comprises ozone.
[0034] The gas delivery systems disclosed herein can produce gas
bubbles of varying size. Bubble size affects several factors
relevant to the V-trough PBR systems disclosed herein. First,
larger bubbles result in more efficient mixing, while smaller
bubbles mix the culture medium less efficiently. Second, larger
bubbles have reduced surface area compared to smaller bubbles,
resulting in less gas exchange with the culture medium. Larger
bubbles thus can have less of an effect on the pH of the system,
while smaller bubbles can be utilized for more efficient gas
diffusion into the system. In some embodiments, bubble size is
controlled by the type of gas delivery system, the pressure of the
gas applied, the density of the gas being introduced into the
system, and the perforation, pore, injection point, aperture or
orifice size through which the gas is introduced into the culture
medium. In some embodiments, the bubbles are between about 1 and
about 3 mm in diameter. In some embodiments, the bubbles are
between about 1 and about 3 mm in diameter, and are used primarily
for mixing the culture medium. In further embodiments, the bubbles
are less than about 1 mm in diameter (i.e. micro bubbles). In some
embodiments, the bubbles are less than about 1 mm in diameter and
are used primarily for gas diffusion into the culture medium. In
still further embodiments, the bubbles are between about 0.001 and
about 500 microns in diameter. In some embodiments, the gas
delivery systems operate at a pressure between about 1 and about 50
psi, and generate bubble size of between about 1 and about 3 mm in
diameter. In some embodiments, air is applied at a bubble size of
about 1 to about 3 mm to aid in mixing the medium.
[0035] In some embodiments, the culture medium in the V-trough
photobioreactor systems disclosed herein is mixed or circulated by
the gas delivery system. In some embodiments, the gas exiting from
the gas delivery system generates an upward movement of biomass and
liquid phase from the axis towards the top of the system. In some
embodiments, the biomass is exposed to light near the top of the
circulation or mixing path. In some embodiments, the medium then
circulates outwards towards the substantially vertical portions of
the base walls, which in some embodiments provides for additional
exposure to light. In some embodiments, the culture medium then
moves down the base walls and back towards the axis, where the
process is repeated continuously or semi-continuously. Further
description of this type of circulation is found in U.S. Pat. No.
5,846,816 to Forth, the contents of which are incorporated herein
by reference in their entireties.
[0036] In some embodiments, the gas delivery system uses positive
pressure to prevent infiltration of water and other components into
the gas delivery system. In further embodiments, perforation, pore,
injection point, aperture or orifice size is selected to prevent
infiltration of molecules, such as proteins, having molecular
weights less than about 30,000 Daltons.
[0037] The gas delivery systems are made of any suitable materials.
In some embodiments, the gas delivery systems comprise ceramic,
stainless steel, rubber, glass, or polyethylene. In some
embodiments, the gas delivery system comprises a line running along
the axis of the V-shaped base, perforated with perforations, pores,
injection points, apertures or orifices along its length. In some
embodiments, the gas delivery system comprises a gas sparging line.
In some embodiments, bubbles are sparged into the medium through
stainless steel, membrane and other materials having the desired
perforation, pore, injection point, aperture or orifice size range.
In some embodiments, the gas delivery system comprises a Graver
Technologies, Glasgow, Del. sintered metal filter with a 1 micron
pore size that is adapted to sparging carbon dioxide into growth
medium. In some embodiments, the perforations, pores, injection
points, apertures or orifices comprise holes and/or slots. In some
embodiments, the holes and/or slots are oriented vertically. In
further embodiments, the holes and/or slots are oriented at an
angle to improve mixing of the medium. In some embodiments, the
holes and/or slots are arranged uniformly along the gas delivery
system. In further embodiments, the holes and/or slots are arranged
randomly along the gas delivery system. In some embodiments, holes
and/or slots are oriented both vertically and at an angle. In some
embodiments, the line or lines comprise perforations, pores,
injection points, apertures or orifices strategically placed along
their length to achieve consistent and congruent pressure along the
line for even gas dispersion. In some embodiments, the gas delivery
systems comprise micro-pore diffusers. In some embodiments, the
perforations, pores, injection points, apertures or orifices
comprise gas injection ports.
[0038] In some embodiments, a single gas delivery system is present
in each V-trough PBR system. In some embodiments, the system
comprises a single line perforated with perforations, pores,
injection points, apertures or orifices. In further embodiments,
the V-trough PBR systems disclosed herein comprise multiple gas
delivery systems. In some embodiments, the system comprises an
array of lines perforated with perforations, pores, injection
points, apertures or orifices. In some embodiments, the gas
delivery system comprises at least one terminal through at least a
portion of one of the side walls defining the cavity of the
V-trough PBR systems disclosed herein.
[0039] In some embodiments where ozone is delivered to the V-trough
PBR systems disclosed herein, ozone is provided at levels that do
not harm the biomass, but kill or inhibit the growth of
contaminants or predators. In some embodiments, ozone is delivered
by a separate line than other gases. In some embodiments, ozone is
delivered by the same line as other gases. In some embodiments,
ozone is applied constantly. In further embodiments, ozone is
applied prophylactically, to prevent contamination rates reaching
detrimental levels in the culture. The amount and timing of the
ozone application for sterilization of the culture is determined by
the contaminant in question. In some embodiments, ozone is applied
at levels between about 0.5 and about 1 mg/L for sterilizing viable
cultures without effecting the targeted biomass.
Carbon Dioxide Delivery System
[0040] The carbon dioxide delivery systems of the V-trough PBR
systems disclosed herein are separated from the gas delivery
systems. Carbon dioxide is required for the growth of many culture
media, such as algae, and thus serves as a carbon source. The
separation of carbon dioxide and gas delivery systems have the
advantage over, e.g., a single system which delivers carbon
dioxide-enriched air, by being able to optimize mixing and carbon
source separately.
[0041] The carbon dioxide delivery systems disclosed herein can
produce carbon dioxide bubbles of varying size. As with other
gasses, carbon dioxide bubble size affects several factors relevant
to the V-trough PBR systems disclosed herein. First, carbon dioxide
bubbles can contribute to mixing of the system, and, as with other
gasses, larger bubbles result in more efficient mixing, while
smaller bubbles mix the culture medium less efficiently. Second,
smaller carbon dioxide bubbles have increased surface area compared
to larger bubbles, resulting in more gas exchange with the culture
medium and more efficient delivery of the carbon source to the
culture medium. This can also affect the pH of the system. In some
embodiments, bubble size is controlled by the type of gas delivery
system, the pressure of the gas applied, the density of the gas
being introduced into the system, and the perforation, pore,
injection point, aperture or orifice size of the through which the
gas is introduced into the culture medium. In some embodiments, the
bubbles are between about 1 and about 3 mm in diameter. In some
embodiments, the bubbles are between about 1 and about 3 mm in
diameter, and are used primarily for mixing the culture medium. In
further embodiments, the bubbles are less than about 1 mm in
diameter (i.e. micro bubbles). In some embodiments, the bubbles are
less than about 1 mm in diameter and are used primarily for gas
diffusion into the culture medium. In still further embodiments,
the bubbles are between about 0.001 and about 500 microns in
diameter for high efficiency gas exchange. In some embodiments, the
gas delivery systems operate at a pressure between about 1 and
about 50 psi, and generate bubble size of between about 1 and about
3 mm in diameter.
[0042] In some embodiments, carbon dioxide is applied at a bubble
size of less than about 1 mm for efficient gas exchange for
enhancing photosynthesis. In some embodiments, carbon dioxide
bubbles are presented in the micron to sub-micron range. For
example, the surface area of ten 100 micron diameter bubbles is
1,000 times the surface area of a bubble having a diameter of 1 mm.
The result is an exponential increase in dissolved carbon dioxide
into the surrounding liquid medium as bubble size reduces.
[0043] In some embodiments, carbon dioxide is applied at a rate and
bubble size, relative to the concentration of carbon
dioxide-consuming biomaterials in the system. In these embodiments,
carbon dioxide is supplied relative to the biomass concentration in
the system for maximum efficiency. In some embodiments, as the
standing biomass concentration increases, the amount of carbon
dioxide required for beneficial growth also increases.
[0044] In some embodiments, the carbon dioxide delivery systems are
disposed adjacent to the gas delivery systems. In further
embodiments, the carbon dioxide delivery systems are disposed at a
different location. In some embodiments, the carbon dioxide
delivery systems are disposed away from the axis to provide
additional mixing along the side walls.
[0045] In some embodiments, the carbon dioxide delivery system uses
positive pressure to prevent infiltration of water and other
components into the carbon dioxide delivery system. In further
embodiments, perforation, pore, injection point, aperture or
orifice size is selected to prevent infiltration of molecules, such
as proteins, having molecular weights less than about 30,000
Daltons.
[0046] The carbon dioxide delivery systems are made of any suitable
materials. In some embodiments, the carbon dioxide delivery system
comprises a line running along the axis of the V-shaped base,
perforated with perforations, pores, injection points, apertures or
orifices distributed along its length. In some embodiments, the gas
delivery system comprises a gas sparging line. In some embodiments,
bubbles are sparged into the medium through stainless steel,
membrane and other materials having the desired perforation, pore,
injection point, aperture or orifice size range. In some
embodiments, the gas delivery system comprises a Graver
Technologies, Glasgow, Del. sintered metal filter with a 1 micron
pore size that is adapted to sparging carbon dioxide into growth
medium. In some embodiments, the perforations, pores, injection
points, apertures or orifices comprise holes and/or slots. In some
embodiments, the holes and/or slots are oriented vertically. In
further embodiments, the holes and/or slots are oriented at an
angle to improve mixing of the medium or more efficient gas
dissolution. In some embodiments, the holes and/or slots are
arranged uniformly along the carbon dioxide delivery system. In
further embodiments, the holes and/or slots are arranged randomly
along the carbon dioxide delivery system. In some embodiments,
holes and/or slots are oriented both vertically and at an angle. In
some embodiments, the line or lines comprise perforations, pores,
injection points, apertures or orifices strategically placed along
their length to achieve consistent and congruent pressure along the
line for even gas dispersion. In some embodiments, the carbon
dioxide delivery systems comprise micro-pore diffusers.
[0047] In some embodiments, a single carbon dioxide delivery system
is present in each V-trough PBR system. In some embodiments, the
system comprises a single line perforated with holes and/or slots.
In further embodiments, the V-trough PBR systems disclosed herein
comprise multiple sources of carbon dioxide for injection into the
culture medium. In some embodiments, the carbon dioxide delivery
system comprises one line perforated with holes and/or slots on
either side of the gas delivery system. In some embodiments, the
system comprises an array of lines perforated with holes and/or
slots. In some embodiments, the carbon dioxide delivery system
comprises at least one terminal through at least a portion of one
of the side walls defining the cavity of the V-trough PBR systems
disclosed herein.
[0048] The ability to independently change the bubble size of the
gas and carbon dioxide delivery systems in the V-trough PBR systems
disclosed herein allows for beneficial productivity of the biomass,
and represents a significant advantage over existing systems.
pH Stabilizers
[0049] As disclosed above, gas and carbon dioxide affect the pH of
the system. To customize and stabilize the pH of the system, pH
buffers are used. The use of pH stabilizers allows gas to be used
at a constant and beneficial flow rate and bubble size for maximum
efficiency in mixing, while carbon dioxide is used at a constant
and beneficial flow rate and bubble size to provide maximum
efficiency in supplying a carbon source to the system, without the
need to vary these parameters to affect the pH.
[0050] In some embodiments, the biomaterials in the V-trough PBR
systems disclosed herein undergo photosynthesis, consuming carbon
dioxide and producing oxygen as a byproduct, consequently affecting
the pH of the system. pH stabilizers serve to stabilize the pH of
the system such that the effects on pH of changing carbon dioxide
and oxygen concentrations are reduced or eliminated. Exemplary pH
stabilizers include calcium carbonate, magnesium, dolomite Ag,
Baker's Lime, limestone, magnesium carbonate, potassium hydroxide,
sodium hydroxide.
[0051] One advantage of the V-trough PBR systems disclosed herein
is that there are multiple methods to control the pH of the system,
including carbon dioxide flow rate and bubble size, mixing gas flow
rate and bubble size, and pH buffers. This allows for an increase
in, for example, carbon dioxide flow rate to provide additional
carbon source to the biomass to improve productivity without the
risk of a detrimental change in pH, since control of pH stabilizers
allows precise control of the pH of the system. Likewise, mixing
rate of the culture medium can be optimized by adjusting the flow
rate and/or bubble size of the gas delivery system without the risk
of a detrimental change in pH as discussed above.
Harvesting Aperture
[0052] In some embodiments, the V-trough PBR systems disclosed
herein further comprise a harvesting aperture for removal of all or
a portion of the biomass from the cavity. In some embodiments, the
harvesting aperture is located through at least a portion of the
distal side wall.
[0053] In some embodiments, harvesting is accomplished by automated
injection of nutrients, trace elements, pH stabilizers and/or water
into the system by the nutrient injection system described below.
In some embodiments, harvesting is accomplished by gravity
drainage. In further embodiments, harvesting is accomplished by a
pumping system. In some embodiments, the pumping system further
comprises pumping into a protein skimmer for further harvesting and
dewatering.
Nutrient Injection System
[0054] In some embodiments, the V-trough PBR systems disclosed
herein further comprise injection pumps for the addition of water,
nutrients, pH stabilizers, trace elements, pH stabilizers, and/or
other components into the system. In illustrative implementations,
the nutrient injection system comprises a dosing pump, a tank for
supplying nutrients, and an inlet port supplied on one of the walls
of the PBR. In some embodiments, the inlet port is supplied through
at least a portion of the proximal side wall. In some embodiments,
the nutrients are supplied via gravity flow into the V-Trough. In
some embodiments where the V-trough system is in the ground, the
nutrient holding containers are at ground level and gravity feed
into the V-trough. In some embodiments where the V-trough system is
above ground, the nutrient holding containers are placed above the
level of the V-Trough for gravity feeding nutrients.
[0055] In some embodiments, the nutrient injection system provides
a means for introducing nutrients, trace elements, water, pH
stabilizers, and/or other components into the system. One skilled
in the art is familiar with these techniques. In some embodiments,
macro and micro nutrients are added to the system at rates
determined by the biomass concentration of the system and the
available light. Exemplary macronutrients are known to those
skilled in the art, and include, but are not limited to, nitrogen,
phosphorus, potassium, calcium, magnesium, and sulfur. Exemplary
micronutrients are also known to those skilled in the art, and
include, but are not limited to, boron, copper, iron chlorine,
manganese, molybdenum, and zinc. Exemplary trace elements include,
but are not limited to, iron, magnesium, and manganese. In some
embodiments, the nutrient injection system feeds from a source
containing a mixture of water, nutrients, pH stabilizers and/or
trace elements customized to the particular biomass being grown. In
further embodiments, the nutrient injection system feeds from
multiple sources containing multiple different mixtures. This
allows for the separation of elements which might demonstrate
undesired reactivity or physical properties, such as chemical
reactions, coagulation, and/or precipitation. In some embodiments,
the nutrient injection system is controlled such that the addition
of water or other liquid, nutrients, pH stabilizers, trace
elements, and/or other components can be independently controlled
to improve the productivity of the biomass.
[0056] In some embodiments, the nutrient injection system comprises
an aperture in at least a portion of the proximal side wall. In
some embodiments, the nutrient injection system comprises a line
comprising perforations, pores, injection points, apertures or
orifices. In some embodiments, the nutrient injection system does
not extend to the distal side wall. In some embodiments, the
nutrient injection system extends less than about half the length
of the cavity. In embodiments where the nutrient injection system
extends less than about half the length of the cavity and comprises
an aperture in at least a portion of the proximal side wall,
harvesting through a distally-located harvesting aperture reduces
the removal of newly or recently injected nutrients, water or pH
buffers during harvest compared to harvesting through a
proximally-located harvesting aperture.
Light Source
[0057] Many biomaterials used in the V-trough PBR systems disclosed
herein require light to grow and produce the desired product. For
light-dependent biomaterials, the amount of light received is a
function of the surface area of the medium exposed to light, volume
of the PBR system, and mixing of the medium within the PBR system.
Consequently, a smaller angle of the V-shaped base may result in a
greater exposure to light, due to decreased volume and increased
mixing. However, a larger angle of the V-shaped base may also
result in greater to exposure to light due to increased surface
area. The fluid dynamics in the V-trough PBR system creates a
mixing of the medium so that the biomaterials are brought to the
light for growth.
Materials
[0058] The V-trough PBR systems disclosed herein can be made from
any suitable materials, of any appropriate thickness. Materials and
thickness can depend on the desired application, particular
biomaterials, growing medium, location and geographic area for
production. In some embodiments, the V-trough PBR systems disclosed
herein comprise plastic liners. In some embodiments, the plastic
liner is high density polyethylene (HDPE), low density polyethylene
(LDPE), polyvinyl chloride (PVC), or ethylene propylene diene
monomer (EPDM). In some embodiments, the plastic liner is between
about 5 to about 60 mm in thickness. In some embodiments, the
liners are semi-rigid. In further embodiments, the liners are
completely rigid. In still further embodiments, the liners are
flexible. In some embodiments, the liners are capable of being
folded, collapsed, or rolled up. In some embodiments, the liners
are formed in a desired shape and have resiliency to form that
molded shape, but still exhibit overall flexibility.
[0059] In some embodiments, the V-trough PBR systems disclosed
herein further comprise foam insulation adhered to the outside of
the PBR. In some embodiments, the foam insulation provides
structural support. In further embodiments, the foam insulation
provides insulation which aids in the maintenance of optimum and
consistent temperatures required for desired productivity of the
biomass. In further embodiments, the V-trough PBR systems disclosed
herein are structurally supported by metal, wood, or earth.
[0060] In some embodiments, the V-trough PBR systems disclosed
herein comprise containers at least partially transparent to light,
and/or which are translucent. In further embodiments, the V-trough
PBR systems disclosed herein comprise PBRs with open tops to allow
light to enter.
Covered V-Trough PBR System
[0061] In some embodiments, the V-trough PBR systems disclosed
herein further comprise a cover for the cavity. In some
embodiments, the cover comprises a greenhouse manifold. In further
embodiments, the greenhouse manifold further comprise glazing
material. In some embodiments, the glazing material is fabricated
from polyethylene, lexan, polycarbonate, clear vinyl, clear
polyvinyl chloride, glass or any other material used for covering
greenhouses and/or growth chambers, which are known to those
skilled in the art. In some embodiments, the cover is affixed to
the cavity. In further embodiments, the cover is held to the cavity
by gravity. In some embodiments, the cover is made of a flexible
material, such that gas evolution can at least partially inflate
the cover, creating a positive pressure system.
[0062] In some embodiments, the cover defines an air volume present
in the system. In these embodiments, the air volume affects the
amount of solar irradiance, relative and absolute humidities, and
ambient temperature of the air in the system. Air volume will
depend on several factors, including, but not limited to,
geographic location and elevation of the system. The air volume is
also dependent on the relationship between the volume of water mass
within the covered system, the water temperature, the air
temperature outside the covered system and the air temperature
inside the covered system. The air volume can be manipulated by
altering the height of the covered system to meet the thermal
demands of the targeted biomass to be grown, or by adjusting the
flexibility of the cover.
[0063] In some embodiments, the cover comprises a flexible sheet,
corrugated rigid panels, corrugated rigid multi-panels, multi-layer
flexible sheets, a combination of corrugated rigid sheets and
flexible films, a combination of flexible and/or rigid glazing
materials that can be used for covering greenhouse and/or growth,
and/or a mixture of the above. In some embodiments, the cover
comprises a single layer glazing material and/or a double layer
glazing material. In some embodiments, the space between the double
layer glazing material comprises air or water which serves as a
means of thermal insulation. In some embodiments, the space between
the double layer glazing material comprises a chemical constituent
that is manipulated via electrical or chemical means to change the
insulation and light transmission properties of the cover.
[0064] In some embodiments, the cover comprises infrared
reflective, infrared absorptive, infrared transmitting materials,
and/or a combination of the foregoing for managing heat generated
from thermal stress. In further embodiments, the cover comprises
wavelength-selective reflective, absorptive, transmitting materials
and/or a combination of the foregoing for manipulation of the
wavelengths of light that enter the system. The selection of the
covering material is dependent on, inter alia, the targeted biomass
and geographic location of the system.
[0065] In some embodiments, the cover comprises the shape of a
loop, A-frame or any other version of greenhouse structures known
to those skilled in the art.
[0066] In some embodiments, the covered V-trough PBR systems
disclosed herein have improved capability to maintain temperature,
pH, and concentrations of nutrients, trace elements and/or other
components of the system.
[0067] In some embodiments, the cover comprises at least one
opening or vent.
[0068] In some embodiments, the covered V-trough PBR systems
disclosed herein provide improved biosecurity by isolating the
biomass production system from potential vectors of contamination,
such as those that can occur from the exposure to the natural
elements. In embodiments where the covered PBR system is a positive
pressure system, contaminants such as dust are preventing from
entering the system through apertures or vents.
Other Features
[0069] In some embodiments, the V-trough PBR systems disclosed
herein further comprise a harvesting aperture. In some embodiments,
the harvesting aperture is disposed through at least a portion of
the distal side wall.
[0070] In some embodiments, the V-trough PBR systems disclosed
herein are level along their lengths, i.e. having a slope of 0. In
further embodiments, the systems are off-level or sloped along
their lengths to increase the ease of harvesting the desired
product at the low end, to drive biomass from one end to a
harvesting end, to assure mixing and turnover within the system, to
skim the top of the culture out of the system, or to allow spill
over for ease of harvesting. In some embodiments, the slope or
leveling of the system is modified by grading of the land on which
the system sits, or by modifying the dimensions of the structural
support on which the system sits. In some embodiments, the offset
of one end of the system to the other is between about 0.5 and
about 6 inches. In some embodiments, a system comprising a cavity
length of about 15 feet comprises an offset of about 0.5 inches. In
further embodiments, a system comprising a cavity length of about
10 feet comprises an offset of about 4 to about 6 inches.
[0071] In some embodiments, the V-trough PBR systems disclosed
herein further comprise temperature and/or pH sensors.
[0072] In some embodiments, the V-trough PBR systems disclosed
herein further comprise controls to add water, nutrients, pH
stabilizers, and further biomass to the system. In some
embodiments, these controls are automated in conjunction with
sensors such that productivity is optimized and held roughly
constant.
[0073] In some embodiments, the V-trough PBR systems disclosed
herein further comprise cooling and/or heating means. In some
embodiments, the cooling and/or heating means comprise at least one
heat exchanger. In further embodiments, the cooling and/or heating
means comprise pan and fan evaporative cooling systems. Such
systems are known to those of skill in the art, and are described
in Bucklin, et al., Fan and Pad Greenhouse Evaporative Cooling
Systems, Univ. of Fla. Dept. of Agric. and Biological Eng'g, Fla.
Coop. Extension Serv., Inst. of Food and Agric. Sci. Circular 1135,
December 1993, available at http://edis.ifas.ufl.edu/ae069 or
http://edis.ifas.ufl.edu/pdffiles/AE/AE06900.pdf, which is
incorporated herein by reference in its entirety. In some
embodiments, the cooling and/or heating means comprise cooling by
water mist sprayed to cool the air surrounding the systems. In some
embodiments where the V-trough PBR systems disclosed herein are in
an enclosed structure, such as a greenhouse or the covered V-trough
PBR systems disclosed herein, further cooling is achieved by
natural or mechanical ventilation of the structure. In some
embodiments, use of the preceding heating and/or cooling means
improves and reduces the operational costs of maintaining the
temperature of the culture medium in the systems disclosed herein.
In some embodiments, the cooling and/or heating means comprise
heating systems and/or covering materials which retain heat loss
via black body radiation. In further embodiments, the V cooling
and/or heating means comprise geothermal heating and/or cooling,
subterranean heating and/or cooling, gas burners, air conditioners,
waste heating and/or cooling from industrial sources, and/or a
combination of the foregoing. In some embodiments, a combination of
foam structural insulation and covering materials is utilized for
maintaining diurnal temperature fluctuation.
[0074] In some embodiments, the V-trough PBR systems disclosed
herein are stand-alone units. In further embodiments, the systems
are dug into the ground for added stability and improved insulation
for maintaining optimum and consistent temperatures required for
desired productivity of the biomass.
[0075] In some embodiments, the V-trough PBR systems disclosed
herein further comprise a drain for harvesting biomaterials. In
some embodiments, the drain is opposite controls such that as
water, nutrients, pH stabilizers and biomass are added to the
system, water is forced out of the drain. In some embodiments, the
drain is on the proximal wall, while the controls are on the distal
wall. In further embodiments, the drain is on the distal wall,
while the controls are on the proximal wall.
[0076] In some embodiments, airlift technology is used to pump
water into or out of the system via the gas and carbon dioxide
delivery systems. In further embodiments, airlift technology is
used to pump water into or out of the system via a separate system.
As known by those skilled in the art, airlift technology is a
process used in aquaculture for moving water via air. The concept
behind the process is to inject air into water at a point in a pipe
and/or vessel where the buoyancy of the bubble lifts the water to
the desired area. The rate of flow is determined by the air flow
into the vessel, the density of the air or gas used, the density of
the water, and the diameter or size of the vessel. Air lift pumping
can be more energy efficient and economical when compared to
conventional means of pumping such as by centrifugal pumps.
[0077] In some embodiments, the V-trough PBR systems disclosed
herein breaks down into small pieces for efficient shipping. In
some embodiments, the system is a turnkey system that can be
delivered to a site, set up, and retrofitted with necessary
components. In some embodiments, the V-trough PBR systems disclosed
herein comprise a structural support, and a first liner disposed on
top of the structural support which comprises the cavity of the
system. In some embodiments, the support structure is foam. In some
embodiments, the support structure comprises stackable pieces which
can be broken down to facilitate shipment. In some embodiments, the
support structure comprises foam blocks. In further embodiments,
the system further comprises a second liner which at least
partially contains the support structure. In some embodiments, the
second liner helps maintain the shape of the support structure. In
some embodiments, the first and second liners are secured to one
another. In some embodiments, the liners are secured by friction.
In further embodiments, the liners are secured by mechanical means.
In still further embodiments, the liners are secured by chemical
means. In some embodiments, the liners are secured by clamps or
adhesives. In some embodiments, the liners are secured by heating.
In some embodiments, the support structure is broken down and
stacked, and the first and/or second liners are folded, collapsed,
or rolled up to facilitate shipment. The ability to break down and
fold, collapse or roll up the separate components of the V-trough
PBR systems disclosed herein facilitates more efficient shipment by
conventional means, where the structural support can be assembled
onsite, either by itself or at least partially contained within the
unrolled, uncollapsed or unfolded second liner to help maintain its
shape, and the first liner placed on the support to form the
cavity.
[0078] In some embodiments, the V-trough PBR systems disclosed
herein further comprise light reflecting means which increase the
amount of light directed into the system.
[0079] In some embodiments, the V-trough PBR systems disclosed
herein further comprise gravity lines. In some embodiments, the
gravity lines are used for harvesting biomass or introducing water,
nutrients, trace elements and/or pH stabilizers without the use of
a pump. In the foregoing embodiments, biomass can be harvested
from, or water, nutrients, trace elements pH stabilizers and/or
other components can be introduced into the culture medium by
varying the elevation of the gravity line and/or fluid source with
respect to the PBR system.
Automated Sensor and Control Systems
[0080] Some embodiments of the V-trough PBR systems disclosed
herein further comprise a sensor and control system for maintaining
and modifying conditions within the V-trough PBR system. Such
systems are known by those skilled in the art. In some embodiments,
the sensor and control system monitors the conditions in the PBR
system and controls various components of the PBR system via
computer, data logger, programmable logic control, any other type
of real time monitoring and control system, or any combination
thereof. In some embodiments, the sensor and control systems
disclosed herein comprise at least one sensor and/or at least one
control.
[0081] In some embodiments, the sensor and control system comprises
a data logging system that is equipped with sensors and controls
which monitor and control various aspects of the V-trough PBR
systems disclosed herein. In some embodiments, the data logging
system comprises a National Instruments, Campbell Scientific,
and/or Allen-Bradley product, or a combination of the
foregoing.
[0082] In some embodiments of the V-trough PBR systems disclosed
herein, the sensors disclosed herein comprise temperature, carbon
dioxide, ozone, dissolved oxygen, light, relative humidity, air
speed, pH, chlorophyll A, phycobilins, turbidity, optical density
and/or electrical conductivity sensors, or any combination of the
foregoing. In some embodiments, the sensors comprise Campbell
Scientific, Honeywell, YSI, National Instruments, and/or Hanna
Instruments products, or a combination of the foregoing. In some
embodiments, real-time feedback from the sensors is analyzed by
software uploaded to the data logger equipment. In some
embodiments, real-time feedback from the sensors is processed and
control systems are adjusted according to set points and
applications set forth in the software program. In some
embodiments, environmental set points are determined with reference
for favorable growing conditions of the targeted biomass. In some
embodiments, the senor systems are wireless systems, reducing the
need for wires and other materials.
[0083] In some embodiments, the sensor and control system is run in
a continuous or semi-continuous mode. In further embodiments, the
sensor and control system is run to adjust and maintain selected
parameters within predetermined limits to provide a beneficial
environment for the selected biomass. In some embodiments, the
sensor and control system controls the amount of light and standing
biomass concentration in the system to improve the productivity of
the system.
[0084] In some embodiments, the sensors disclosed herein monitor
air temperature and humidity and the controls disclosed herein
adjust these properties using cooling and/or heating means. In some
embodiments, the sensors disclosed herein monitor the temperature
of the culture medium and the controls disclosed herein control the
heating and/or cooling system to maintain and/or control the
temperature.
[0085] In some embodiments where the V-trough PBR system is
covered, the sensors disclosed herein monitor the carbon dioxide
and dissolved oxygen in the air space to determine the amount of
gas that leaves the system.
[0086] In some embodiments, the sensors disclosed herein monitor
the pH of the culture medium and the controls disclosed herein
maintain and/or adjust desired pH thresholds of the culture medium
for the targeted biomass. In some embodiments, the controls
disclosed herein maintain or adjust desired pH thresholds by
stabilizing or adjusting the pH of the culture medium by adjusting
or maintaining a combination of the flow rate and bubble size of
gas and carbon dioxide introduced into the system, the addition of
pH stabilizers, and/or other factors, or a combination of the
foregoing.
[0087] In some embodiments, the sensors disclosed herein monitor
chlorophyll A and/or phycobilin concentration in the culture medium
to determine the amount of biomass in the system. Chlorophyll A and
phycobilins are photo-harvesting pigments in algae and
cyanobacteria. If cyanobacteria is not the biomass that is targeted
for production, then the phycobilin concentration can be used to
determine the amount of cyanobacteria contamination within the
system.
[0088] In some embodiments, the sensors disclosed herein monitor
the amount of light entering the PBR system, and the controls
disclosed herein adjust or maintain the harvest rate to compensate
for the amount of light that is entering the system. In some
embodiments, light sensors and controls enable the operation of the
PBR system at a desired productivity as determined by the light
level.
[0089] In some embodiments, the sensors disclosed herein comprise
one or more turbidity sensors, chlorophyll A sensors and/or optical
density sensors. In these embodiments, the foregoing sensors are
utilized individually or in conjunction with one another to measure
real-time biomass concentrations in the system. In some
embodiments, the controls disclosed herein utilize the real-time
biomass concentration measurements determined by the sensors
disclosed herein to control the harvest rate, nutrient injection
rate, contamination rate, or a combination of the foregoing. In
these embodiments, the controls disclosed herein initiate nutrient
injection and/or harvesting depending on the productivity in the
system. In some embodiments, electrical conductivity sensors
measure the salt content of the water, and the controls disclosed
herein provide salinity and fertilizer salts in the system to
adjust to the desired concentration. In some embodiments, the
controls disclosed herein maintain or adjust the nutrient injection
rate based on electrical conductivity measurements made by the
sensors disclosed herein. In these embodiments, a desired or target
electrical conductivity level is determined relative to the
targeted biomass for production.
[0090] In some embodiments, sensors disclosed herein measure
contamination of the medium by the productivity rate of the PBR
system and the difference between the turbidity and chlorophyll A
concentration in the system. In some embodiments, contamination is
monitored by one or more phycobilin sensors, where the targeted
biomass is not a cyanobacteria. In some embodiments, the controls
disclosed herein apply contamination treatments the PBR system to
maintain desired productivity by killing, inhibiting or reducing
the concentration of potential contaminants that inhibit or effect
biomass productivity. In some embodiments, ozone is applied to the
system to prevent contamination. In further embodiments, ozone is
applied prophylactically, to prevent contamination rates reaching
detrimental levels in the culture. The amount and timing of the
ozone application for sterilization of the culture is determined by
the contaminant in question. In some embodiments, ozone is applied
at levels between about 0.5 and about 1 mg/L for sterilizing viable
cultures without effecting the targeted biomass. In some
embodiments, the sensor and control system comprises an ozone
sensor and control for ozone application, wherein ozone is adjusted
and maintained within a predetermined range to prevent
contamination rates from reaching detrimental levels in the
culture. In some embodiments, ozone is adjusted and maintained
between about 0.5 and about 1 mg/L of culture. In some embodiments,
ozone levels between about 0.5 and about 1 mg/L are sufficient to
kill or prevent the growth of contaminants, but will not harm
biomaterials such as Nannochloropsis.
[0091] The Figures that follow demonstrate how the full spectrum of
solar radiation can be used by splitting the full spectrum into
selected and non-selected wavelengths of radiation.
[0092] FIG. 1 shows an illustrative embodiment of the V-trough PBR
systems disclosed herein, where substantially V-shaped base 100
(comprising two base walls 125 with sloped portions 135 and
substantially vertical portions 140), proximal side wall 130 and
distal side wall 160 define cavity 145. FIG. 1 also shows sloped
portions 135 of base walls 125 meeting proximate to axis 190, along
which gas delivery system 170 lies, which base walls further define
interior angle 195. FIG. 1 further shows two carbon dioxide
delivery systems 150 disposed parallel to axis 190 and gas delivery
system 170. FIG. 1 still further shows carbon dioxide delivery
systems 150 comprising carbon dioxide terminals 120 through
proximal side wall 130, and gas delivery system 170 comprising gas
delivery terminal 110 also through proximal side wall 130. FIG. 1
also shows that the system further comprises apertures 180 through
proximal side wall 130, which may be apertures for a nutrient
injection system.
[0093] FIG. 2 shows another illustrative embodiment of the V-trough
PBR systems disclosed herein, where nutrient injection system 260
feeds from nutrient solutions 200 and 210, as well as pH stabilizer
220 to inject these components through proximal side wall 130. FIG.
2 shows that the system further comprises gas delivery system 170,
carbon dioxide delivery systems 150, sensors 230 (distributed at
three different positions along base wall 125), and a harvesting
aperture 240 trough distal side wall 160, feeding to harvesting
receptacle 250.
[0094] FIG. 3 shows another illustrative embodiment of the V-trough
PBR systems disclosed herein, looking end on at proximal side wall
130, where sloped portions 135 and substantially vertical portions
140 of base walls 125, proximal side wall 130 and the distal side
wall (not pictured) define cavity 145. FIG. 3 also shows sloped
portions 135 of base walls 125, which define interior angle 195,
cover 300, and culture medium 310. FIG. 3 also shows carbon dioxide
delivery systems 150, separated from gas delivery system 170, and
nutrient injection apertures 180 through proximal side wall 130.
Further, FIG. 3 shows support structure 320.
[0095] FIG. 4 shows another illustrative embodiment of the V-trough
PBR systems disclosed herein, looking end on at distal side wall
160, where sloped portions 135 and substantially vertical portions
140 of base walls 125, the proximal side wall (not pictured) and
distal side wall 160 define cavity 145. FIG. 4 further shows sloped
portions 135 of base walls 125 defining interior angle 195, and
also shows harvesting aperture 240 through distal side wall 160.
Further, FIG. 4 shows support structure 320.
[0096] FIG. 5 shows a flowchart of an illustrative embodiment of
the method for growing a biomass using the V-trough PBR systems
disclosed herein wherein biomass is dispensed into a PBR 500, gas
is supplied for mixing 510 via a gas delivery system, carbon
dioxide is supplied 520 through a carbon dioxide delivery system,
light is delivered 530for biomass growth, and the biomass is
harvested 540.
[0097] FIG. 6 shows an end-on view of the proximal side wall of an
illustrative embodiment of the V-trough PBR systems disclosed
herein which illustrates the circulation pattern 620 on one side of
the system (circulation pattern on the other side not shown). FIG.
6 shows gas bubbles 610 as the major contributor to circulation,
with carbon dioxide bubbles 600 additionally contributing, but less
significantly.
[0098] FIG. 7 shows an exploded aspected view of an illustrative
embodiment of the V-trough PBR systems disclosed herein, where
disassembled system comprises a molded liner 700 defining cavity
145, which is ready for assembly with proximal side wall 130,
distal side wall 160 and base walls 125.
EQUIVALENTS
[0099] Those skilled in the art will recognize, or be able to
ascertain, using no more than routine experimentation, numerous
equivalents to the specific embodiments described specifically
herein. Such equivalents are intended to be encompassed in the
scope of the following claims.
* * * * *
References