ALGAE BIOFUEL CARBON DIOXIDE DISTRIBUTION SYSTEM
FIELD OF THE INVENTION
The present invention pertains generally to processes for abating
pollution and for producing biofuel from algae. More particularly, the present
invention pertains to the supply of pollutants to algae cells for use as nutrients
to support growth. The present invention is particularly, but not exclusively,
useful as a system and method for producing biofuel from algae fed with
carbon dioxide distributed through the system.
BACKGROUND OF THE INVENTION
As worldwide petroleum deposits decrease, there is rising concern over
shortages and the costs that are associated with the production of
hydrocarbon products. As a result, alternatives to products that are currently
processed from petroleum are being investigated. In this effort, biofuel such
as biodiesel has been identified as a possible alternative to petroleum-based
transportation fuels. In general, a biodiesel is a fuel comprised of mono-alkyl
esters of long chain fatty acids derived from plant oils or animal fats. In
industrial practice, biodiesel is created when plant oils or animal fats react
with an alcohol, such as methanol.
For plant-derived biofuel, solar energy is first transformed into chemical
energy through photosynthesis. The chemical energy is then refined into a
usable fuel. Currently, the process involved in creating biofuel from plant oils
is expensive relative to the process of extracting and refining petroleum. It is
possible, however, that the cost of processing a plant-derived biofuel could be
reduced by maximizing the rate of growth of the plant source and by
minimizing the costs of feeds needed to support the plant growth. Because
algae is known to be one of the most efficient plants for converting solar
energy into cell growth, it is of particular interest as a biofuel source.
However, current algae processing methods have failed to result in a cost
effective algae-derived biofuel.
In overview, the biochemical process of photosynthesis provides algae
with the ability to convert solar energy into chemical energy. During cell
growth, this chemical energy is used to drive synthetic reactions, such as the
formation of sugars or the fixation of nitrogen into amino acids for protein
synthesis. Excess chemical energy is stored in the form of fats and oils as
triglycerides. Thus, the creation of oil in algae only requires sunlight, carbon
dioxide and the nutrients necessary for formation of triglycerides.
Nevertheless, with the volume requirements for a fuel source, the costs
associated with the inputs are high.
One possible source of carbon dioxide and other nutrients that support
cell growth is found in flue gases from power plants or other combustion
sources. Further, when present in flue gases, these nutrients are considered
pollutants that must be properly disposed of. Therefore, use of nutrients from
flue gases to support cell growth will abate pollution.
In light of the above, it is an object of the present invention to provide a
system and method for producing algae-derived biofuel which reduces input
costs. Another object of the present invention is to provide a system and
method for producing algae-derived biofuel that causes pollution abatement.
Still another object of the present invention is to provide a system for
supplying nutrients to algae cells in the form of pollutants scrubbed from flue
gases. Another object of the present invention is to provide a system for
recycling the effluent from a medium for growing algae as a scrubber solution.
Another object of the present invention is to provide a system for producing
algae-derived biofuel that defines a flow path for continuous movement of the
algae, its processed derivatives, and the medium fostering its growth. Yet
another object of the present invention is to provide a system and method for
producing biofuel from pollutant-fed algae that is simple to implement, easy to
use, and comparatively cost effective.
SUMMARY OF THE INVENTION
In accordance with the present invention, a system is provided for
producing high oil content biofuel from algae fed with pollutants. In this
manner, the system serves to produce an environmentally-friendly fuel while
abating pollution. Structurally, the system includes a scrubber having a
chamber for receiving a pollutant-contaminated fluid stream and a scrubber
solution. Typically, the fluid stream comprises flue gas from a combustion
source, such as a power plant, which is polluted with carbon dioxide, sulfur
oxides, and/or nitrogen oxides. Further, the scrubber solution is typically a
caustic or sodium bicarbonate.
For purposes of the present invention, the system also includes a
bioreactor for growing algae cells with high oil content. Structurally, the
bioreactor includes at least one chemostat and a plug flow reactor. More
particularly, the chemostat is a continuously-stirred flow reactor that has an
input port, a conduit, and an output port. Preferably, the conduit is formed by
an endless, open raceway that receives and holds a medium, and a
paddlewheel spanning the conduit is provided to circulate the medium through
the conduit. For purposes of the present invention, the plug flow reactor is
positioned relative to the chemostat to receive overflow medium containing
algae cells from the chemostat. Specifically, the plug flow reactor includes an
input port that receives the overflow medium from the output port of the
chemostat. Further, the plug flow reactor is in the form of an open raceway
that includes a conduit for continuously moving the medium downstream
under the influence of gravity.
In addition to the scrubber and bioreactor, the system includes an
algae separator. Specifically, the algae separator is positioned in fluid
communication with the plug flow reactor to remove the algae cells from the
plug flow reactor's conduit. Downstream of the algae separator, the system
includes a channel for recycling an effluence from the plug flow reactor to the
scrubber for reuse as the scrubber solution. Further, the system includes an
apparatus for lysing algae cells to unbind oil from the algae cells. For the
present invention, the lysing apparatus is positioned to receive algae cells
from the algae separator. Downstream of the lysing apparatus, the system
includes an oil separator that receives the lysed cells and withdraws the oil
from remaining cell matter. The oil separator has an outlet for the remaining
cell matter which is in fluid communication with the chemostat. Further, the
system may include a hydrolyzing device that is interconnected between the
oil separator and the chemostat. In addition to the cell matter outlet, the oil
separator includes an outlet for the oil in fluid communication with a biofuel
reactor. In a known process, the biofuel reactor causes an alcohol to react
with the oil to synthesize biofuel and, as a byproduct, glycerin. Structurally,
the biofuel reactor includes a glycerin exit that is in fluid communication with
the plug flow reactor.
In operation, the flue gas from the power plant is flowed through the
chamber of the scrubber. At the same time, the scrubber solution is sprayed
into the scrubber chamber to trap the pollutants in the flue gas. The scrubber
solution with the entrapped pollutants is then delivered to the chemostat
through its input port. Also, a nutrient mix may be fed into the chemostat
through the input port to form, along with the scrubber solution, a medium for
growing algae cells. As the paddlewheel circulates the medium through the
conduit of the chemostat, the algae cells grow using solar energy and
converting the pollutants and other nutrients to cell matter. Preferably, a
continuous flow of the medium washes the algae cells and constantly
removes them from the chemostat as overflow.
After the overflow medium is removed from the chemostat, it is
received in the plug flow reactor and is treated in order to trigger the
production of oil in the form of triglycerides in the algae cells. After passing
along the conduit of the plug flow reactor, the effluent, including algae cells,
passes through the algae separator which removes the algae cells from the
effluent. Thereafter, the effluent is recycled through a channel back to the
scrubber for reuse as the scrubber solution. At the same time, the algae cells
are delivered to the cell lysis apparatus. Then, the cell lysis apparatus lyses
the cells to unbind the oil from the remaining cell matter. This unbound cell
material is received by the oil separator from the cell lysis apparatus. Next,
the oil separator withdraws the oil from the remaining cell matter and
effectively forms two streams of material. The stream of remaining cell matter
is transferred to the hydrolysis apparatus where the cell matter is broken into
small units which are more easily absorbed by algae cells during cell growth.
Thereafter, the hydrolyzed cell matter is delivered to the chemostat to serve
as a source of nutrition for the algae cells growing therein. At the same time,
the stream of oil is transmitted from the oil separator to the biofuel reactor. In
the biofuel reactor, the oil is reacted with an alcohol to form biofuel and a
glycerin byproduct. The glycerin byproduct is fed back into the plug flow
reactor to serve as a source of carbon for the algae cells therein during the
production of intracellular oil.
BRIEF DESCRIPTION OF THE DRAWINGS
The novel features of this invention, as well as the invention itself, both
as to its structure and its operation, will be best understood from the
accompanying drawing, taken in conjunction with the accompanying
description, in which the Figure is a schematic view of the system for
producing biofuel from pollutant-fed algae in accordance with the present
invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the Figure, a system for producing biofuel from pollutantfed
algae in accordance with the present invention is shown and generally
designated 10. As shown, the system 10 includes a scrubber 12 for
scrubbing a pollutant-contaminated fluid stream. Specifically, the scrubber 12
includes a chamber 14 and an input port 16a for receiving flue gas from a
combustion source such as a power plant 18 and a scrubber solution 20.
Typically, the flue gas includes pollutants such as carbon dioxide, sulfur
oxides, and/or nitrogen oxides. Also, the scrubber solution 20 typically
comprises sodium hydroxide or sodium bicarbonate. As further shown, the
scrubber 12 includes a solution outlet 22 and a gas outlet 24. Also, the
system 10 includes an oxidation stage 26 for oxidizing pollutants in the flue
gas to facilitate their removal from the flue gas. As shown, the oxidation stage
26 is interconnected between the power plant 18 and the scrubber 12.
As further shown, the system 10 includes a bioreactor 28 comprised of
at least one chemostat 30 for growing algae cells (exemplary cells depicted at
32) and a plug flow reactor 34 for treating the algae cells 32 to trigger cell
production of triglycerides. Preferably, and as shown, both the chemostat 30
and the plug flow reactor 34 are open raceways, though closed systems are
also contemplated. Further, such open systems 10 can cover several acres
of land to optimize economies of scale. For purposes of the present
invention, the system 10 includes an algae separator 36 for removing the
algae cells 32 from the plug flow reactor 34.
As shown in the Figure, the chemostat 30 includes a conduit 38. As
further shown, the conduit 38 is provided with an input port 40 that is in fluid
communication with the solution outlet 22 of the scrubber chamber 14. For
purposes of the present invention, the input port 40 is also in communication
with a reservoir (not illustrated) holding a nutrient mix (indicated by arrow 42).
Preferably, the nutrient mix 42 includes phosphorous, nitrogen, sulfur and
numerous trace elements necessary to support algae growth that are not
provided to the bioreactor 28 by the scrubber solution 20. Further, the
chemostat 30 is provided with a paddlewheel 44 for causing the medium 46
formed by the scrubber solution 20 and the nutrient mix 42 to continuously
circulate around the conduit 38 at a predetermined fluid flow velocity. Also,
each conduit 38 is provided with an output port 48 in communication with the
plug flow reactor 34.
As shown, the plug flow reactor 34 includes an input port 50a for
receiving overflow medium (indicated by arrow 46') with algae cells 32 from
the output port 48 of the chemostat 30. As further shown, the plug flow
reactor 34 includes a conduit 52 for passing the medium 46" with algae cells
32 downstream. The flow rate of the medium 46" is due solely to gravity and
the force of the incoming overflow medium 46' from the chemostat 30.
Preferably, the plug flow reactor 34 has a substantially fixed residence time of
about one to four days. For purposes of the present invention, the system 10
is provided with a reservoir (not shown) that holds a modified nutrient mix
(indicated by arrow 54). Further, the conduit 52 is provided with an input port
50b for receiving the modified nutrient mix 54. In order to manipulate the
cellular behavior of algae cells 32 within the plug flow reactor 34, the modified
nutrient mix 54 may contain a limited amount of a selected constituent, such
as nitrogen or phosphorous. For instance, the nutrient mix 54 may contain no
nitrogen. Alternatively, the algae cells 32 may exhaust nutrients such as
nitrogen or phosphorous in the nutrient mix 42 at a predetermined point in the
plug flow reactor 34. By allowing such nutrients to be exhausted, desired
behavior in the algae cells 32 can be caused without adding a specific
modified nutrient mix 54. Further, simply water can be added through the
modified nutrient mix 54 to compensate for evaporation. In addition to input
ports 50a and 50b, the conduit 52 is further provided with an input port 50c to
receive other matter.
In the Figure, the algae separator 36 is shown in fluid communication
with the conduit 52 of the plug flow reactor 34. For purposes of the present
invention, the algae separator 36 separates the algae cells 32 from the
medium 46" and the remaining nutrients therein through flocculation and/or
filtration. As further shown, the algae separator 36 includes an effluence outlet
56 and an algae cell outlet 60. For purposes of the present invention, the
system 10 includes a channel 58 providing fluid communication between the
effluence outlet 56 and the scrubber 12 through a solution input port 16b in
the scrubber chamber 14.
Also, the system 10 includes a cell lysis apparatus 62 that receives
algae cells 32 from the algae outlet 60 of the algae separator 36. As shown,
the cell lysis apparatus 62 is in fluid communication with an oil separator 64.
For purposes of the present invention, the oil separator 64 is provided with
two outlets 66, 68. As shown, the outlet 66 is connected to a hydrolysis
apparatus 70. Further, the hydrolysis apparatus 70 is connected to the input
port 40 in the conduit 38 of the chemostat 30.
Referring back to the oil separator 64, it can be seen that the outlet 68
is connected to a biofuel reactor 72. It is further shown that the biofuel reactor
72 includes two exits 74, 76. For purposes of the present invention, the exit
74 is connected to the input port 50c in the conduit 52 of the plug flow reactor
34. Additionally or alternatively, the exit 74 may be connected to the input
port 40 in the chemostat 30. Further, the exit 76 may be connected to a tank
or reservoir (not shown) for purposes of the present invention.
In operation of the present invention, pollutant-contaminated flue gas
(indicated by arrow 78) is directed from the power plant 18 to the oxidation
stage 26. At the oxidation stage 26, nitrogen monoxide in the flue gas 78 is
oxidized by nitric acid or by other catalytic or non-catalytic technologies to
improve the efficiency of its subsequent removal. Specifically, nitrogen
monoxide is oxidized to nitrogen dioxide. Thereafter, the oxidized flue gas
(indicated by arrow 80) is delivered from the oxidation stage 26 to the
scrubber 12. Specifically, the oxidized flue gas 80 enters the chamber 14 of
the scrubber 2 through the input port 16a. Upon the entrance of the flue gas
80 into the chamber 14, the scrubber solution 20 is sprayed within the
chamber 14 to adsorb or otherwise trap the pollutants in the flue gas 80 as is
known in the field of scrubbing. With its pollutants removed, the clean flue
gas (indicated by arrow 82) exits the scrubber 12 through the gas outlet 24.
At the same time, the scrubber solution 20 and the pollutants exit the scrubber
2 through the solution outlet 22.
After exiting the scrubber 12, the scrubber solution 20 and pollutants
(indicated by arrow 84) enter the chemostat 30 through the input port 40.
Further, the nutrient mix 42 is fed to the chemostat 30 through the input port
40. In the conduit 38 of the chemostat 30, the nutrient mix 42, scrubber
solution 20 and pollutants form the medium 46 for growing the algae cells 32.
This medium 46 is circulated around the conduit 38 by the paddlewheel 44.
Further, the conditions in the conduit 38 are maintained for maximum algal
growth. For instance, in order to maintain the desired conditions, the medium
46 and the algae cells 32 are moved around the conduit 38 at a preferred fluid
flow velocity of approximately fifty centimeters per second. Further, the
amount of algae cells 32 in the conduit 38 is kept substantially constant.
Specifically, the nutrient mix 42 and the scrubber solution 20 with pollutants
are continuously fed at selected rates into the conduit 38 through the input
port 40, and an overflow medium 46' containing algae cells 32 is continuously
removed through the output port 48 of the conduit 38.
After entering the input port 50a of the plug flow reactor 34, the
medium 46" containing algae cells 32 moves downstream through the conduit
52 in a plug flow regime. Further, as the medium 46" moves downstream, the
modified nutrient mix 54 may be added to the conduit 52 through the input
port 50b. This modified nutrient mix 54 may contain a limited amount of a
selected constituent, such as nitrogen or phosphorous. The absence or small
amount of the selected constituent causes the algae cells 32 to focus on
energy storage rather than growth. As a result, the algae cells 32 form
triglycerides.
At the end of the conduit 52, the algae separator 36 removes the algae
cells 32 from the remaining effluence (indicated by arrow 86). Thereafter, the
effluence 86 is discharged from the algae separator 36 through the effluence
outlet 56. In order to recycle the effluence 86, it is delivered through channel
58 to the input port 16b of the scrubber 12 for reuse as the scrubber solution
20. Further, the removed algae cells (indicated by arrow 88) are delivered to
the cell lysis apparatus 62. Specifically, the removed algae cells 88 pass out
of the algae cell outlet 60 to the cell lysis apparatus 62. For purposes of the
present invention, the cell lysis apparatus 62 lyses the removed algae cells 88
to unbind the oil therein from the remaining cell matter. After the lysing
process occurs, the unbound oil and remaining cell matter, collectively
identified by arrow 90, are transmitted to the oil separator 64. Thereafter, the
oil separator 64 withdraws the oil from the remaining cell matter as is known
in the art. After this separation is performed, the oil separator 64 discharges
the remaining cell matter (identified by arrow 92) out of the outlet 66 of the oil
separator 64 to the input port 40 of the chemostat 30.
In the chemostat 30, the remaining cell matter 92 is utilized as a source
of nutrients and energy for the growth of algae cells 32. Because small units
of the remaining cell matter 92 are more easily absorbed or otherwise
processed by the growing algae cells 32, the remaining cell matter 92 may
first be broken down before being fed into the input port 40 of the chemostat
30. To this end, the hydrolysis apparatus 70 is interconnected between the oil
separator 64 and the chemostat 30. Accordingly, the hydrolysis apparatus 70
receives the remaining cell matter 92 from the oil separator 64, hydrolyzes the
received cell matter 92, and then passes hydrolyzed cell matter (identified by
arrow 94) to the chemostat 30.
Referring back to the oil separator 64, it is recalled that the remaining
cell matter 92 was discharged through the outlet 66. At the same time, the oil
withdrawn by the oil separator 64 is discharged through the outlet 68.
Specifically, the oil (identified by arrow 96) is delivered to the biofuel reactor
72. In the biofuel reactor 72, the oil 96 reacts with alcohol, such as methanol,
to create mono-alkyl esters, i.e., biofuel fuel. This biofuel fuel (identified by
arrow 98) is released from the exit 76 of the biofuel reactor 72 to a tank,
reservoir, or pipeline (not shown) for use as fuel. In addition to the biofuel fuel
98, the reaction between the oil 96 and the alcohol produces glycerin as a
byproduct. For purposes of the present invention, the glycerin (identified by
arrow 100) is pumped out of the exit 74 of the biofuel reactor 72 to the input
port 50c of the plug flow reactor 34.
In the plug flow reactor 34, the glycerin 100 is utilized as a source of
carbon by the algae cells 32. Importantly, the glycerin 100 does not provide
any nutrients that may be limited to induce oil production by the algae cells 32
or to trigger flocculation. The glycerin 100 may be added to the plug flow
reactor 34 at night to aid in night-time oil production. Further, because
glycerin 100 would otherwise provide bacteria and/or other nonphotosynthetic
organisms with an energy source, limiting the addition of
glycerin 100 to the plug flow reactor 34 only at night allows the algae cells 32
to utilize the glycerin 100 without facilitating the growth of foreign organisms.
As shown in the Figure, the exit 74 of the biofuel reactor 72 may also be in
fluid communication with the input port 40 of the chemostat 30 (connection
shown in phantom). This arrangement allows the glycerin 00 to be provided
to the chemostat 30 as a carbon source.
While the particular Algae Biofuel Carbon Dioxide Distribution System
as herein shown and disclosed in detail is fully capable of obtaining the
objects and providing the advantages herein before stated, it is to be
understood that it is merely illustrative of the presently preferred embodiments
of the invention and that no limitations are intended to the details of
construction or design herein shown other than as described in the appended
claims.
What is claimed is:
1. A system for producing biofuel from pollutant-fed algae which
comprises:
a scrubber having a chamber for receiving a pollutantcontaminated
fluid stream;
a scrubber solution received in the chamber for scrubbing the
pollutant-contaminated fluid stream;
a bioreactor for growing algae cells with high oil content, said
bioreactor having an input port for receiving the scrubber solution with
pollutants for use as nutrients to support algae cell growth;
an algae separator in fluid communication with the bioreactor for
removing the algae cells from an effluence;
a channel for recycling the effluence from the bioreactor to the
scrubber for use as the scrubber solution; and
a device for processing the algae cells to form biofuel.
2. A system as recited in claim 1 wherein the pollutants are
selected from a group comprising carbon dioxide, sulfur oxides and nitrogen
oxides.
3. A system as recited in claim 1 wherein the scrubber solution is
selected from a group comprising sodium hydroxide and sodium bicarbonate.
4. A system as recited in claim 1 further comprising an oxidation
unit for treating the pollutant-contaminated fluid stream before being received
in the scrubber.
5. A system as recited in claim 4 wherein the oxidation unit
oxidizes nitrogen monoxide in the pollutant-contaminated fluid stream.
6. A system as recited in claim 1 wherein the bioreactor comprises:
at least one chemostat formed with a conduit for growing algae
therein, wherein the chemostat includes the input port for receiving the
scrubber solution and for receiving a nutrient mix to form a medium for
maximum algae growth, and wherein the chemostat has an output port
for passing the medium with algae growth from the conduit of the
chemostat;
a means for continuously moving the medium through the
conduit of the chemostat at a predetermined fluid flow velocity;
a plug flow reactor formed with a conduit having an input port for
receiving the medium with algae growth from the chemostat; and
a means for adding a modified nutrient mix to the medium with
algae growth in the plug flow reactor, wherein the modified nutrient mix
comprises a limited amount of a selected constituent to trigger high oil
production in the algae growth.
7. A system as recited in claim 6 wherein the device for processing
the algae to form biofuel comprises:
an apparatus for lysing the algae cells removed from the conduit
to unbind oil within the algae cells;
an oil separator for withdrawing the oil from remaining cell
matter; and
a reactor for receiving the oil from the oil separator and for
synthesizing biofuel and glycerin from said oil.
8. A system as recited in claim 7 wherein the remaining cell matter
is a byproduct and the glycerin is a byproduct, and wherein the device for
processing the algae further comprises a means for recycling at least one
byproduct to the bioreactor to support growth of algae cells with high oil
content.
9. A system for producing biofuel from pollutant-fed algae which
comprises:
a means for scrubbing a pollutant-contaminated fluid stream
with a scrubber solution;
a means for feeding the scrubber solution holding the pollutants
to a bioreactor to form a medium therein;
a means for promoting growth of high oil content algae cells in
the medium in the bioreactor, with said algae cells converting the
pollutants into cell matter during cell growth;
a means for separating the algae cells from the medium in the
bioreactor to form an effluence;
a means for recycling the effluence for use as the scrubber
solution; and
a means for processing the algae cells to form biofuel.
10. A system as recited in claim 9 further comprising a means for
oxidizing the pollutant-contaminated fluid stream.
11. A system as recited in claim 9 wherein the pollutants are
selected from a group comprising carbon dioxide, sulfur oxides, and nitrogen
oxides.
12. A system as recited in claim 9 wherein the scrubber solution is
selected from a group comprising sodium hydroxide and sodium bicarbonate.
13. A method for producing biofuel from pollutant-fed algae which
comprises the steps of:
scrubbing a pollutant-contaminated fluid stream with a scrubber
solution;
feeding the scrubber solution holding the pollutants to a
bioreactor;
growing algae cells with high oil content in the bioreactor, with
said algae cells converting the pollutants into cell matter during cell
growth;
separating the algae cells from an effluence from the bioreactor;
recycling the effluence for use as the scrubber solution; and
processing the algae cells to form biofuel.
14. A method as recited in claim 13 further comprising the step of
treating the pollutant-contaminated fluid stream before the scrubbing step.
15. A method as recited in claim 14 wherein the treating step
includes oxidizing nitrogen oxides in the pollutant-contaminated fluid stream.
16. A method as recited in claim 13 wherein the pollutants are
selected from a group comprising carbon dioxide, sulfur oxides, and nitrogen
oxides.
17. A method as recited in claim 13 wherein the scrubber solution is
selected from a group comprising caustic soda and sodium bicarbonate.
18. A method as recited in claim 13 wherein the bioreactor includes
at least one chemostat and a plug flow reactor, and wherein the chemostat is
formed with a conduit for growing algae therein and an input port for receiving
the scrubber solution and a nutrient mix to form a medium for maximum algae
growth, with the chemostat having an output port for passing the medium with
algae growth from the conduit of the chemostat, and further wherein the plug
flow reactor is formed with a conduit having an input port for receiving the
medium with algae growth from the chemostat, with the method further
comprising the steps of:
continuously moving the medium through the conduit of the
chemostat at a predetermined fluid flow velocity; and
adding a modified nutrient mix to the medium with algae growth
in the plug flow reactor, wherein the modified nutrient mix comprises a
limited amount of a selected constituent to trigger high oil production in
the algae growth.
19. A method as recited in claim 18 wherein the processing step
includes:
lysing the algae cells removed from the conduit to unbind oil
within the algae cells;
withdrawing the oil from remaining cell matter; and
synthesizing biofuel and glycerin from the oil.
20. A method as recited in claim 19 wherein the remaining cell
matter is a byproduct and the glycerin is a byproduct, and wherein the
processing step includes recycling at least one byproduct to the bioreactor to
support growth of algae cells with high oil content.