U.S. patent application number 14/245624 was filed with the patent office on 2014-09-18 for revolving algal biofilm photobioreactor systems and methods.
The applicant listed for this patent is Martin Anthony Gross, Zhiyou Wen. Invention is credited to Martin Anthony Gross, Zhiyou Wen.
Application Number | 20140273174 14/245624 |
Document ID | / |
Family ID | 51528825 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140273174 |
Kind Code |
A1 |
Gross; Martin Anthony ; et
al. |
September 18, 2014 |
REVOLVING ALGAL BIOFILM PHOTOBIOREACTOR SYSTEMS AND METHODS
Abstract
An algal growth system can include a vertical reactor that can
include a flexible sheet material, where the flexible sheet
material can be configured to facilitate the growth and attachment
of algae. The vertical reactor can include a shaft, where the shaft
can be associated with and can supports the flexible sheet material
and a drive motor, where the drive motor can be coupled with the
shaft such that the flexible sheet material can be selectively
actuated. The algal growth system can include a raceway pond, where
the vertical reactor can be positioned at least partially within
the raceway pond, where the raceway pond can include a fluid
reservoir, where the flexible sheet material can be configured to
pass through the fluid reservoir during operation of the algal
growth system, a contacting liquid, where the contacting liquid can
be retained within the fluid reservoir and can includes nutrients
that facilitate the growth of the algae, and a liquid phase and a
gaseous phase, where the liquid phase can include rotating the
flexible sheet material through the contacting liquid retained in
the fluid reservoir and the gaseous phase can include rotating the
flexible sheet material through gaseous carbon dioxide.
Inventors: |
Gross; Martin Anthony;
(Ames, IA) ; Wen; Zhiyou; (Ames, IA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gross; Martin Anthony
Wen; Zhiyou |
Ames
Ames |
IA
IA |
US
US |
|
|
Family ID: |
51528825 |
Appl. No.: |
14/245624 |
Filed: |
April 4, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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14212479 |
Mar 14, 2014 |
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14245624 |
|
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61783737 |
Mar 14, 2013 |
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Current U.S.
Class: |
435/257.1 ;
435/292.1 |
Current CPC
Class: |
C12N 11/02 20130101;
C12M 25/02 20130101; C12N 11/14 20130101; C12M 27/14 20130101; C12M
21/02 20130101; C12N 1/12 20130101 |
Class at
Publication: |
435/257.1 ;
435/292.1 |
International
Class: |
C12N 1/12 20060101
C12N001/12 |
Claims
1. An algal growth system comprising: (a) a vertical reactor
comprising; (i) a flexible sheet material, the flexible sheet
material being configured to facilitate the growth and attachment
of algae; (ii) a shaft, wherein the shaft is associated with and
supports the flexible sheet material; and (iii) a drive motor, the
drive motor being coupled with the shaft such that the flexible
sheet material is selectively actuated; (b) a raceway pond, the
vertical reactor being positioned at least partially within the
raceway pond, the raceway pond comprising; (i) a fluid reservoir,
wherein the flexible sheet material is configured to pass through
the fluid reservoir during operation of the algal growth system;
and (ii) a contacting liquid, wherein the contacting liquid is
retained within the fluid reservoir and includes nutrients that
facilitate the growth of the algae; and (c) a liquid phase and a
gaseous phase, wherein the liquid phase comprises rotating the
flexible sheet material through the contacting liquid retained in
the fluid reservoir and the gaseous phase comprises rotating the
flexible sheet material through gaseous carbon dioxide.
2. The algal growth system of claim 1, further comprising a
harvesting mechanism.
3. The algal growth system of claim 1, wherein the harvesting
mechanism is a squeegee.
4. The algal growth system of claim 1, wherein the flexible sheet
material is selected from the group consisting of cheesecloth,
fiberglass, porous PTFE coated fiberglass, chamois, vermiculite,
microfiber, synthetic chamois, burlap, cotton duct, velvet, vinyl
laminated nylon, polyester, wool, acrylic, lanolin, woolen,
cashmere, leather, silk, lyocell, hemp fabric, polyurethane, olefin
fiber, polylactide, and carbon fiber.
5. The algal growth system of claim 1, wherein the algae is
selected from the group consisting of Nannochloropsis, Scenedesmus,
Haematococcus, Botryococcus, Spirulina, Dunaliella, Arthrospira,
Porphyridium, Phaeodactylum, Nitzschia, Crypthecodinium and
Schizochytrium.
6. The algal growth system of claim 1, further comprising an
enclosed greenhouse.
7. The algal growth system of claim 6, wherein the enclosed
greenhouse has a higher carbon dioxide concentration than the
atmosphere.
8. The algal growth system of claim 1, wherein the drive motor is
configured to rotate the flexible sheet material on a predetermined
schedule.
9. The algal growth system of claim 1, wherein the flexible sheet
material is a biofilm.
10. The algal growth system of claim 1, wherein the flexible sheet
material is configured to grow and retain the algae until the algae
is physically removed.
11. The algal growth system of claim 1, wherein the algal growth
system is configured for industrial use.
12. A method of growing algae comprising the steps of: providing an
algal growth system comprising; (a) a vertical reactor comprising;
(i) a flexible sheet material, the flexible sheet material being
configured to facilitate the growth and attachment of algae; (ii) a
shaft, wherein the shaft is associated with and supports the
flexible sheet material; and (iii) a drive motor, the drive motor
being coupled with the shaft such that the flexible sheet material
is selectively actuated; and (b) a raceway pond, the vertical
reactor being positioned at least partially within the raceway
pond, the raceway pond comprising; (i) a fluid reservoir, wherein
the flexible sheet material is configured to pass through the fluid
reservoir during operation of the algal growth system; and (ii) a
contacting liquid, wherein the contacting liquid is retained within
the fluid reservoir and includes nutrients that facilitate the
growth of the algae; rotating the flexible sheet material of the
algal growth system through a liquid phase such that the flexible
sheet material passes through the contacting liquid retained in the
fluid reservoir; rotating the flexible sheet material of the algal
growth system through a gaseous phase such that the flexible sheet
material passes through gaseous carbon dioxide; and harvesting the
algae from the flexible sheet material.
13. The method of growing algae of claim 12, wherein the algal
growth system further comprises an enclosed greenhouse.
14. The method of growing algae of claim 12, wherein the algae is
selected from the group consisting of Nannochloropsis, Scenedesmus,
Haematococcus, Botryococcus, Spirulina, Dunaliella, Arthrospira,
Porphyridium, Phaeodactylum, Nitzschia, Crypthecodinium and
Schizochytrium.
15. The method of growing algae of claim 12, wherein the flexible
sheet material is selected from the group consisting of
cheesecloth, fiberglass, porous PTFE coated fiberglass, chamois,
vermiculite, microfiber, synthetic chamois, burlap, cotton duct,
velvet, vinyl laminated nylon, polyester, wool, acrylic, lanolin,
woolen, cashmere, leather, silk, lyocell, hemp fabric,
polyurethane, olefin fiber, polylactide, and carbon fiber.
16. The method of growing algae of claim 12, wherein the algal
growth system is configured for industrial use.
17. The method of growing algae of claim 12, further comprising the
step of rotating the algal growth system according to a
predetermined schedule.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
non-provisional patent application Ser. No. 14/212,479, filed Mar.
14, 2014, which claims the priority benefit of U.S. provisional
patent application Ser. No. 61/783,737, filed Mar. 14, 2013, and
hereby incorporates the same applications herein by reference in
their entirety.
TECHNICAL FIELD
[0002] Embodiments of the technology relate, in general, to biofilm
technology, and in particular to a revolving algal biofilm
photobioreactor (RABP) for simplified biomass harvesting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The present disclosure will be more readily understood from
a detailed description of some example embodiments taken in
conjunction with the following figures:
[0004] FIG. 1 depicts a flow chart illustrating considerations that
may need to be addressed by example embodiments described
herein.
[0005] FIG. 2 depicts a top view of microalgae being grown on
polystyrene foam.
[0006] FIG. 3 depicts a perspective view of an example embodiment
of a revolving algal biofilm photobioreactor.
[0007] FIG. 4 depicts a schematic front view of the revolving algal
biofilm photobioreactor shown in FIG. 3.
[0008] FIG. 5 depicts a top view of microalgae being grown on a
variety of materials.
[0009] FIG. 6 depicts a bar chart of harvesting frequencies for an
algal strain.
[0010] FIG. 7 depicts a perspective view of a straight vertical
reactor according to one embodiment.
SUMMARY
[0011] An algal growth system can include a vertical reactor that
can include a flexible sheet material, where the flexible sheet
material can be configured to facilitate the growth and attachment
of algae. The vertical reactor can include a shaft, where the shaft
can be associated with and can supports the flexible sheet material
and a drive motor, where the drive motor can be coupled with the
shaft such that the flexible sheet material can be selectively
actuated. The algal growth system can include a raceway pond, where
the vertical reactor can be positioned at least partially within
the raceway pond, where the raceway pond can include a fluid
reservoir, where the flexible sheet material can be configured to
pass through the fluid reservoir during operation of the algal
growth system, a contacting liquid, where the contacting liquid can
be retained within the fluid reservoir and can includes nutrients
that facilitate the growth of the algae, and a liquid phase and a
gaseous phase, where the liquid phase can include rotating the
flexible sheet material through the contacting liquid retained in
the fluid reservoir and the gaseous phase can include rotating the
flexible sheet material through gaseous carbon dioxide.
[0012] A method of growing algae can include the step of providing
an algal growth system that can include a vertical reactor that can
include a flexible sheet material, where the flexible sheet
material can be configured to facilitate the growth and attachment
of algae. The vertical reactor can include a shaft, where the shaft
can be associated with and can supports the flexible sheet material
and a drive motor, where the drive motor can be coupled with the
shaft such that the flexible sheet material can be selectively
actuated. The algal growth system can include a raceway pond, where
the vertical reactor can be positioned at least partially within
the raceway pond, where the raceway pond can include a fluid
reservoir, where the flexible sheet material can be configured to
pass through the fluid reservoir during operation of the algal
growth system, a contacting liquid, where the contacting liquid can
be retained within the fluid reservoir and can includes nutrients
that facilitate the growth of the algae. The method of growing
algae can include rotating the flexible sheet material of the algal
growth system through a liquid phase such that the flexible sheet
material passes through the contacting liquid retained in the fluid
reservoir, rotating the flexible sheet material of the algal growth
system through a gaseous phase such that the flexible sheet
material passes through gaseous carbon dioxide, and harvesting the
algae from the flexible sheet material.
DETAILED DESCRIPTION
[0013] Various non-limiting embodiments of the present disclosure
will now be described to provide an overall understanding of the
principles of the structure, function, and use of the proficiency
tracking systems and processes disclosed herein. One or more
examples of these non-limiting embodiments are illustrated in the
accompanying drawings. Those of ordinary skill in the art will
understand that systems and methods specifically described herein
and illustrated in the accompanying drawings are non-limiting
embodiments. The features illustrated or described in connection
with one non-limiting embodiment may be combined with the features
of other non-limiting embodiments. Such modifications and
variations are intended to be included within the scope of the
present disclosure.
[0014] Reference throughout the specification to "various
embodiments," "some embodiments," "one embodiment," "some example
embodiments," "one example embodiment," or "an embodiment" means
that a particular feature, structure, or characteristic described
in connection with any embodiment is included in at least one
embodiment. Thus, appearances of the phrases "in various
embodiments," "in some embodiments," "in one embodiment," "some
example embodiments," "one example embodiment," or "in an
embodiment" in places throughout the specification are not
necessarily all referring to the same embodiment. Furthermore, the
particular features, structures or characteristics may be combined
in any suitable manner in one or more embodiments.
[0015] Traditionally, algae are grown in open raceway ponds or
enclosed photobioreactors, where algae cells are in suspension and
are harvested through sedimentation, filtration, or centrifugation.
Due to the small size (3-30 .mu.m) of algae cells and the dilute
algae concentration (<1% w/v), gravity sedimentation of
suspended cells often takes a long time in a large footprint
settling pond. Filtration of algal cells from the culture broth can
result in filter fouling. Centrifugation can achieve high harvest
efficiency; however, the capital investment and operational cost
for a centrifugation system can be prohibitively expensive. Due to
these drawbacks, an alternative method for harvesting and
dewatering algae biomass may be advantageous.
[0016] Described herein are example embodiments of revolving algal
biofilm photobioreactor systems and methods that can simplify
biomass harvesting. In one example embodiment, systems and methods
can provide cost effective harvesting of algae biomass. In some
embodiments, systems and methods can be used to produce algae for
both biofuel feedstock and aquacultural feed sources. In some
embodiments, algal cells can be attached to a material that can be
rotated between a nutrient-rich liquid phase and a carbon dioxide
rich gaseous phase such that alternative absorption of nutrients
and carbon dioxide can occur. The algal cells can be harvested by
scrapping from the surface to which they are attached, which can
eliminate harvest procedures commonly used in suspension
cultivation systems, such as sedimentation or centrifugation. It
will be appreciated that systems and methods described herein can
be combined with sedimentation, centrifugation, or any other
suitable processes.
[0017] The examples discussed herein are examples only and are
provided to assist in the explanation of the apparatuses, devices,
systems and methods described herein. None of the features or
components shown in the drawings or discussed below should be taken
as mandatory for any specific implementation of any of the
apparatuses, devices, systems or methods unless specifically
designated as mandatory. For ease of reading and clarity, certain
components, modules, or methods may be described solely in
connection with a specific figure. Any failure to specifically
describe a combination or sub-combination of components should not
be understood as an indication that any combination or
sub-combination is not possible. Also, for any methods described,
regardless of whether the method is described in conjunction with a
flow diagram, it should be understood that unless otherwise
specified or required by context, any explicit or implicit ordering
of steps performed in the execution of a method does not imply that
those steps must be performed in the order presented but instead
may be performed in a different order or in parallel.
[0018] Example embodiments described herein can mitigate air and
water pollution while delivering high value bio-based products and
animal feeds from microalgae. Example embodiments of RABP
technology can play a critical role in creating an algal culture
system that can economically produce algae biomass for, for
example, biofuel production and aquacultural feed production.
Microalgae may have a significant impact in the renewable
transportation fuels sector. Example embodiments can grow
microalgae that can be used in biofuel production with a low
harvest cost. Algae, if produced economically, may also serve as a
primary feed source for the US aquaculture industry.
[0019] Example systems and methods can include developing a
biofilm-based microalgae cultivation system (RABP) that could be
widely adapted by the microalgae industry for producing, for
example, fuels and high value products. Over the past few years
microalgae has been rigorously researched as a promising feedstock
for renewable biofuel production. Microalgae use photosynthesis to
transform carbon dioxide and sunlight into energy. This energy is
stored in the cell as oils, which have a high energy content. The
oil yield from algae can be significantly higher than that from
other oil crops. Algae oil can generally be easily converted to
biodiesel and could replace traditional petroleum-based diesel. In
addition to fuel production, microalgae have also been rigorously
researched for the potential to produce various high value products
such as animal feed, omega-3 polyunsaturated fatty acids, pigments,
and glycoproteins.
[0020] Referring to FIG. 1, in spite of the strong potential of
microalgae in various applications, the high cost of algae
production can still be the major limitation in industrial scale
operation. According to the United States Department of Energy's
final report on the Aquatic Species Program and the recent National
Algal Biofuel Technology Roadmap, there are three main areas that
may need to be focused on in order to make algae cultivation
economically viable, including strain development, control of
contamination by native species, and reducing the high cost of
biomass harvesting and dewatering. Example embodiments may minimize
the cost associated with biomass harvesting and dewatering of algal
cells from an aqueous culture system.
[0021] Generally, research on algae cultivation is done using
suspended algae culture. This culture method can have drawbacks
including the issue with harvesting. Example embodiments can
promote a simple economical harvesting method. Example embodiments
can include a mechanized harvesting system, which can remove
concentrated algae in-situ from an attachment material and can
minimize the amount of de-watering needed post-harvest. Example
embodiments can optimize gas mass transfer, where growth in an
enclosed greenhouse 40 may provide the ability to increase CO2
concentration inside the reactor. Generally, at higher CO2
concentrations, the growth rate of algae will increase. Example
embodiments can utilize minimal growth medium, where the triangular
design in example embodiments may reduce the chemical costs of
growth medium and may reduce the total water needed for the growth.
In one embodiment, such advantages may be accomplished by
submerging only the lowest elevated corner of a triangle system
needs into the medium.
[0022] Referring to FIG. 2, microalgae can be grown on the surface
of polystyrene foam. FIG. 2 illustrates how algae can be harvested
by scraping the surface of the foam. The mechanical separation can
result in biomass with water content similar to centrifuged samples
and the residual biomass left on the surface can serve as an ideal
inoculum for subsequent growth cycles. However, such systems can be
limited by the use of polystyrene foam which is not a renewable and
environmental friendly material. The rigidity of the styrene foam
may also limit its application in embodiments of rotational systems
and methods described herein.
[0023] Referring to FIGS. 3 and 4, an example embodiment of a
revolving algal biofilm Photobioreactor (RABP) 10, in which the
algal cells 18 can be attached to a solid surface of a supporting
material 12, is disclosed. The system can keep the algal cells
fixed in place and can bring nutrients to the cells, rather than
suspend the algae in a culture medium. As shown in FIGS. 3 and 4,
algal cells can be attached to a material 12 that is rotating
between a nutrient-rich liquid phase 15 and a CO2-rich gaseous
phase 16 for alternative absorption of nutrients and CO2. The algal
biomass can be harvested by scrapping the biomass from the attached
surface with a harvesting squeegee 20 (FIG. 4) or other suitable
device or system. In example embodiments, the naturally
concentrated biofilm can be in-situ harvested during the culture
process, rather than using an additional sedimentation or
flocculation step for harvesting, for example. The culture can
enhance the mass transfer by directly contacting algal cells with
CO2 molecules in gaseous phase, where traditional suspended culture
systems may have to rely on the diffusion of CO2 molecules from
gaseous phase to the liquid phase, which may be limited by low
gas-liquid mass transfer rate. Example embodiments may only need a
small amount of water by submerging the bottom of the triangle 22
in liquid 14 while maximizing surface area for algae to attach.
Example embodiments can be scaled up to an industrial scale because
the system may have a simple structure and can be retrofit on
existing raceway pond systems 102 (FIG. 7). Example embodiments can
be used in fresh water systems and can be adapted to saltwater
culture systems. For example, embodiments of this system can be
placed in the open ocean instead of in a raceway pond reactor. In
this example application, the ocean can naturally supply the algae
with sufficient sunlight, nutrient, water, and CO2, which in turn
may decrease operational costs.
[0024] Still referring to FIGS. 3 and 4, embodiments of the system
can include a drive motor 24, a gear system 26 that can rotate
drive shafts 28, drive shafts 28 that can rotate a flexible
material 12, a flexible sheet material 12 that can rotate into
contact with liquid 14 and can allow algae 18 to attach thereto.
The motor 24 can include a gear system 26 or pulley system that can
drive one or a plurality of shafts 28, where the shafts 28 can
rotate the flexible sheet material 12 in and out of a contacting
liquid 14, for example. Embodiments can also include a liquid
reservoir 30, mister, water dripper, or any other suitable
component or mechanism that can keep algae, which can be attached
to the flexible sheet material 12, moist. Embodiments can include
any suitable scraping system, vacuum system or mechanism for
harvesting the algae 18 from the flexible sheet material 12.
[0025] In an example embodiment, a generally triangular system 22
can be provided. Such a configuration can be beneficial in
maximizing the amount of sunlight algae is exposed to. However
versions of the system can be designed, for example, in any
configuration that includes a "sunlight capture" part 32 which can
be exposed to air and sunlight, and a "nutrient capture" part 34
which can be submerged into a nutrient solution. A straight
vertical design is contemplated, which may be the simplest and most
cost efficient design because such a system may minimize the amount
of wasted space and may maximize the amount of algae produced in a
small area by growing this system vertically. Alternative designs
can include a straight vertical reactor 100, a reactor that is
straight but slightly angled to provide more surface area for
sunlight to hit, a cylindrical reactor, or a square shaped
reactor.
[0026] Referring to FIG. 5, any suitable material 12, such as any
suitable flexible fabric, can be used with the systems and methods
described herein to grow any suitable material. For example, the
microalga Chlorella, such as Chlorella vulgaris can be grown on
materials such as, muslin cheesecloth, armid fiberglass, porous
PTFE coated fiberglass, chamois, vermiculite, microfiber, synthetic
chamois, fiberglass, burlap, cotton duct, velvet, Tyvek, polylactic
acid, abrased polylactic acid, vinyl laminated nylon, polyester,
wool, acrylic, lanolin, woolen, cashmere, leather, silk, lyocell,
hemp fabric, Spandex, polyurethane, olefin fiber, polylactide,
Lurex, carbon fiber, and combinations thereof.
[0027] It will be appreciated that any suitable algal strain 18
(including cyanobacteria) as well as fungal strains, such as
strains that can be used in aquaculture feed, animal feed,
nutraceuticals, or biofuel production can be used. Such strains can
include Nannochloropsis sp., which can be used for both biofuel
production and aquacultural feed; Scenedesmus sp., a green
microalga that can be used in wastewater treatment as well as for
fuel production feedstock; Haematococcus sp, which can produce a
high level of astaxanthin; Botryococcus sp. a green microalga with
high oil content; Spirulina sp. a blue-green alga with high protein
content; Dunaliella sp. a green microalga containing a large amount
of carotenoids; a group of microalgae species producing a high
level of long chain polyunsaturated fatty acids can include
Arthrospira, Porphyridium, Phaeodactylum, Nitzschia,
Crypthecodinium and Schizochytrium. Any suitable parameter,
including gaseous phase CO2 concentration, harvesting frequency,
the rotation speed of the RABP reactor, the depth of the biofilm
harvested, the ratio of submerged portion to the air-exposure
portion of the RABP reactor, or the gap between the different
modules of the RABP system can be optimized for any suitable
species.
[0028] Referring to FIG. 6, any harvesting schedule can be used in
accordance with example embodiments described herein. The mechanism
of harvesting biomass from the biofilm can be, for example,
scraping or vacuum. Biomass productivity may vary by species and
any suitable harvesting time is contemplated to maximize such
productivity. For example, as shown in FIG. 6, of this specific
species as a function of harvesting time by growing the algae on a
RABP system then harvesting the cells at different durations. As
shown in FIG. 6, for Chlorella the optimal harvest frequency may be
every 7 days. In example embodiments, managing other parameters
such as CO2 concentration and nutrient loading may also impact
algal growth performance.
[0029] In various embodiments disclosed herein, a single component
can be replaced by multiple components and multiple components can
be replaced by a single component to perform a given function or
functions. Except where such substitution would not be operative,
such substitution is within the intended scope of the
embodiments.
[0030] Some of the figures can include a flow diagram. Although
such figures can include a particular logic flow, it can be
appreciated that the logic flow merely provides an exemplary
implementation of the general functionality. Further, the logic
flow does not necessarily have to be executed in the order
presented unless otherwise indicated. In addition, the logic flow
can be implemented by a hardware element, a software element
executed by a computer, a firmware element embedded in hardware, or
any combination thereof.
[0031] The foregoing description of embodiments and examples has
been presented for purposes of illustration and description. It is
not intended to be exhaustive or limiting to the forms described.
Numerous modifications are possible in light of the above
teachings. Some of those modifications have been discussed, and
others will be understood by those skilled in the art. The
embodiments were chosen and described in order to best illustrate
principles of various embodiments as are suited to particular uses
contemplated. The scope is, of course, not limited to the examples
set forth herein, but can be employed in any number of applications
and equivalent devices by those of ordinary skill in the art.
Rather it is hereby intended the scope of the invention to be
defined by the claims appended hereto.
* * * * *