WO2002086053A1 - Improvements relating to bioreactors - Google Patents

Improvements relating to bioreactors Download PDF

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Publication number
WO2002086053A1
WO2002086053A1 PCT/GB2002/001800 GB0201800W WO02086053A1 WO 2002086053 A1 WO2002086053 A1 WO 2002086053A1 GB 0201800 W GB0201800 W GB 0201800W WO 02086053 A1 WO02086053 A1 WO 02086053A1
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WIPO (PCT)
Prior art keywords
compartment
illumination
microorganisms
light
tube
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Application number
PCT/GB2002/001800
Other languages
French (fr)
Inventor
Niels-Henrik Norsker
Heimir Haraldsson
Royce Clarke
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Bioprocess A/S
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Publication date
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Publication of WO2002086053A1 publication Critical patent/WO2002086053A1/en

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Classifications

    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
    • A01G33/00—Cultivation of seaweed or algae
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M21/00—Bioreactors or fermenters specially adapted for specific uses
    • C12M21/02—Photobioreactors
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M27/00—Means for mixing, agitating or circulating fluids in the vessel
    • C12M27/18—Flow directing inserts
    • C12M27/20—Baffles; Ribs; Ribbons; Auger vanes
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M29/00—Means for introduction, extraction or recirculation of materials, e.g. pumps
    • C12M29/18—External loop; Means for reintroduction of fermented biomass or liquid percolate
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
    • C12M31/00—Means for providing, directing, scattering or concentrating light
    • C12M31/10—Means for providing, directing, scattering or concentrating light by light emitting elements located inside the reactor, e.g. LED or OLED

Definitions

  • This invention relates to apparatus and a method for growing microorganisms such as algae in a bioreactor.
  • bioreactor The simplest designs of bioreactor are open or closed tanks or vats with stirrers and optionally air lift devices to agitate the microorganisms .
  • Lights can be provided through windows in the tank for photosynthetic organisms such as algae, but problems arise in larger tanks as the transmitted light does not penetrate through into the main container to a satisfactory extent, so the algal culture does not receive sufficient light.
  • Lights have previously been immersed in the tank as has been taught in US3986297 but this solution becomes less efficient with increasing tank sizes. Simply illuminating with higher intensity light has been found to reduce the efficiency, as the culture experiences photo inhibition and the cells nearest the surface of the high-intensity lamps are damaged.
  • the present invention provides apparatus for growing microorganisms, the apparatus comprising a container for cultivation of suspended microorganisms, an illumination compartment in fluid communication with the container, a light source capable of transmitting light into the suspension of microorganisms in the illumination compartment and a circulating device to circulate the suspension of microorganisms between the container and the illumination compartment.
  • the illumination compartment can be opaque or transparent, of metal, glass or plastics materials and can be entirely transparent or translucent, or can have regions that are opaque, for example, steel regions, with windows of transparent or translucent areas between the opaque regions .
  • Completely transparent illumination compartments are preferred to mixed opaque - transparent.
  • the illumination compartment can have the light source emitting light into the culture through the wall of the compartment, but the light source can be outside or inside the tube as desired.
  • Preferred embodiments have the light source inside the illumination compartment, as this arrangement results in a simpler light path geometry and hence lower light transmission loss compared to the situation if the light source was located outside the illumination compartment, shining inwards.
  • Certain illumination compartments can be made from steel or other non-transparent metals, and can be provided with an inner light source to illuminate the cells from within the compartment. Therefore, the illumination compartment does not need to have any window regions through which light can penetrate, but this remains a preferred option.
  • the illumination compartment typically comprises an elongate tube, typically of shallow depth or diameter e.g.l-5cm.
  • the illumination compartment preferably has a lightpath (path from plane of light entrance to opposite wall) equal to the light penetration depth of culture of normal operating condition cell density, e.g. 5-20 cm. and it can preferably include folds, baffles and/or bends to enable the compartment to be accommodated in a small space in order to save room, and to agitate the cells passing through it.
  • the penetration depth of light in the culture is the depth under which the light intensity is below the compensation point of the algal culture, which of course will vary with species and condition.
  • a practical value of the penetration depth is therefore the depth under which the light intensity is less than 10 ⁇ E/m2/sec.
  • the light compartment is typically at least partially of arcuate or circular cross-section, but this is optional, and other cross- sections can be used, such as square, flat, or other complex shapes engineered to enhance flow characteristics and light penetration as desired.
  • the flow pattern in the illumination compartment is preferably not laminar, but turbulent. This may be accomplished by dimensioning the compartment to have a sufficiently high Reynolds number. At Reynolds numbers higher than 2300 the flow ceases to be laminar and starts assuming a turbulent pattern. Reynolds numbers higher than 10000 are preferred. The cells thereby avoid photo damage caused by extended exposure to high light intensities encountered at the surfaces of the compartment, nearest the light sources. The transition, however, is not entirely predictable only from the Reynolds number, and in hydraulically smooth compartments, flow could be laminar at Reynolds numbers higher than 2300.
  • the inner surface of the illumination compartment can be adapted to enhance the turbulent character of the flow, by having baffles or ridges etc. Reducing the flow path will increase the Reynolds number and hence increase the turbulent character of the flow.
  • the illumination compartment having the light source internally, e.g. the light sources and the compartment being concentric, the light source may itself add to the turbulent character of the flow.
  • the illumination compartment typically allows illumination of the culture through small glass areas relative to the volume of the culture, high light flux through the transparent areas of the illumination compartment, and short exposure cycles that do not subject the cells to damage through the high light intensities.
  • the entire culture is typically illuminated in short light exposure cycles (e.g. 30 seconds or less) as it passes through the illumination compartment, followed by a longer dark period e.g. 10 minutes and less) as it circulates through the main tank.
  • the cells receive a high light dose while passing through the illumination compartment or "light loop", and use up the energy received while circulating in the main container.
  • More illumination compartments can also be added to an existing reactor allowing a scale up of the reactor capacity without substantial re-engineering.
  • a good light source comprises metal halide lamps, high pressure sodium lamps but other high intensity discharge lamps may be used, especially those that mimic natural daylight.
  • the construction of the illumination compartment can be made to allow exchange of lamps without interrupting the culture flow in the compartment .
  • all light radiating from the light source inside the tube enters the culture flowing over the surface of the glass tube.
  • This optical arrangement means that the light transmission losses between light source and culture are substantially reduced or eliminated, which otherwise can be substantial, i.e. 50% or more in certain light reflector systems.
  • Light intensities entering the culture over the area of the glass tube can be very high: up to 10000 ⁇ E/m2/sec, and typically 4-5000 ⁇ E/m2/sec.
  • the cell density and the flow rate of microorganisms through the illumination compartment is typically carefully controlled.
  • the flow rate is typically adjusted to avoid illuminating the microorganisms beyond their capacity to convert and store the absorbed light energy.
  • Embodiments of the invention offer the possibility of using very high intensity light sources and controlled exposure times to the light and darkness, ensuring a high degree of utilization of the light flux compared to known reactors, including tubular reactors.
  • a suitable tubular reactor for use as an illumination compartment is disclosed by Pirt et al in J. Chem. Tech. Biotechnol., 1983. 33B, 35-58, which is herein incorporated by reference.
  • This reactor may use light in an intensity corresponding to natural sunlight (2000 ⁇ E ⁇ f 2 sec "1 ) over a short lightpath (1 cm) under which conditions the biomass may reach high densities while the concomitant light utilization efficiency is low.
  • About 90W/m2 were reported absorbed by cells in the reactor at full sunlight intensity which is 900 W/m2 or 2000 ⁇ E/m2/sec. At an absorption of 90 W/m2 , the light that enters the culture can be absorbed by a biomass density of 22 g D.W. per litre, although densities of around 8-16g DW/1 may be beneficial.
  • the main container typically also has a light source, which illuminates the cells in the main container, optionally at a much lower total flux (e.g. 20%) as compared with the light loop.
  • a light source which illuminates the cells in the main container, optionally at a much lower total flux (e.g. 20%) as compared with the light loop.
  • the invention also provides a method of growing photosynthetic microorganisms in suspension, the method comprising circulating the suspension of microorganisms between a main container and an illumination compartment, wherein the microorganisms are illuminated at high intensity in the illumination compartment, for example, at higher intensities than those which prevail in the main container.
  • the cells When the cells first enter the illumination compartment, the cellular pools of photosynthetically produced metabolites, such as chloroplastic ATP and NADPH will be low as a result of staying in the dark for extended periods.
  • the cells will therefore be able to assimilate and store relatively large amounts of photosynthetic energy during the light cycle in the illumination tube. They then pass into the main container where later steps of the photosynthesis takes place - initially during exhaustion of the photosynthetically provided pools of ATP and NADPH, then, after depletion of these pools, using ATP and NADH generated by respiration.
  • the illumination compartment is typically illuminated at an intensity of 5-10 mE m "2 sec "1 at the glass interface. Opposite to the glass interface the light intensity can be reduced to very low levels (less than 5-10 ⁇ E m "2 sec "1 ) .
  • the cells are typically illuminated along the entire length of the compartment for the time that it takes for the cell to pass through i.e. the hydraulic residence time. This can be in the order of 10-60 seconds.
  • the dimensions of the illumination compartment and flow rate between the main tank and the illumination compartment can be adjusted to provide a suitable residence time.
  • FIG. 1 is a schematic view of a reactor.
  • a bioreactor has a main reactor tank 1 with a mechanical stirring device such as an impeller 2 which agitates a suspension of algal cells in the reactor tank 1.
  • the tank has an oxygen electrode 5 which feeds back levels of oxygen to the controller of the impeller 2, and a pH electrode 6 to indicate and potentially control the pH of the cell suspension.
  • the impeller 2 drives the fluid in the tank 1 through an outlet 10 of the tank 1 via feeding pipe 16 into the illumination compartment, shaped for example as an elongate steel tube 20 of diameter e.g. 20-40 cm.
  • the impeller 2 is used only for stirring the main tank and the cells are driven through the light loop by a pump, for example a pump 15.
  • the pump 15 is an air-lift pump it can drive the fluid from the tube 20 back to the main ank 1 s the photosynthetic energy conversion in the tube 20 ay be more efficient as a result of oxygen, depletion taking place in the main tank l.
  • the tube 20 may surround a transparent glass or plastics tube 22.
  • the glass tube 22 may extend through the length of the tube 20 and transmits light fron light sources shi ing into the bore of the tube 22 ;;rom a very high intensity light source 25-
  • the light sources A ⁇ be of any intensity of more than 4 m>3 m “3 sec “1 , typically from 4-10 mE “2 sec “1 " . Lower intsnsities can also be used.
  • the glass tube 22 in this example has a length > 3 m and a diamet r of > 0.2 m e.g. 225mm diameter.
  • the diameter of the light loop tube 20 is typically 0.234 m.
  • the combination of tube diameter and lamp flux reduces the intensity of the light at the tube glass surface to the maximum desired value (e.g. 10,000 E M-2 sec-1) sir.iple geometric "dilution".
  • the maximum desired value e.g. 10,000 E M-2 sec-1 sir.iple geometric "dilution".
  • the useful range of light intensity is 2-10000 ⁇ E M-2 sec-1, and is typically >400 ⁇ ⁇ E M-2 sec-1.
  • a glass tube 3 ma be placed in che reactor allowing a light source 4 to illuminate the reactor from within.
  • the intensity and total flux of this light source is generally much less than the light source 25, typically 10-25%.
  • the tube 20 may be posr.tioned either horizontally or vertically.
  • the hor:.2ontal position is preferred as the light source 25 nay be easily removed from the tube 25, or for filXing and venting the tube 20,
  • the cells are driven through the annulus between the ou ' ⁇ * tube 20 and the inner glass tube 22 in a state of .urbulent flow.
  • This flow may be established by inj' ⁇ cting air at a low point into a vertical tube 15.
  • This tube therefore functions as the riser of an air l ⁇ t z pump.
  • the air is vented from the system through a gas escape 7 from the headspace of reactor tank 1.
  • Caroon dioxide may be added to the air for control of pH. 1
  • the annulus between the tube 22 and 20 is typically 5-
  • the ligh -saturated cells ret irn to

Abstract

A method and apparatus for growing microorganisms, in which the microorganisms are circulated between a main reactor and an illumination compartment. The microorganisms are illuminated at very high intensity in the illumination compartment and are returned to the main compartment thereafter. The illumination compartment is usefully in the form of a tube through which the microorganisms are passed. The illumination compartment is typically at least partially of arcuate or circular cross-section, and can be baffled to enhance flow characteristics.

Description

Improvements relating to bioreactors
This invention relates to apparatus and a method for growing microorganisms such as algae in a bioreactor.
The simplest designs of bioreactor are open or closed tanks or vats with stirrers and optionally air lift devices to agitate the microorganisms . Lights can be provided through windows in the tank for photosynthetic organisms such as algae, but problems arise in larger tanks as the transmitted light does not penetrate through into the main container to a satisfactory extent, so the algal culture does not receive sufficient light. Lights have previously been immersed in the tank as has been taught in US3986297 but this solution becomes less efficient with increasing tank sizes. Simply illuminating with higher intensity light has been found to reduce the efficiency, as the culture experiences photo inhibition and the cells nearest the surface of the high-intensity lamps are damaged.
The present invention provides apparatus for growing microorganisms, the apparatus comprising a container for cultivation of suspended microorganisms, an illumination compartment in fluid communication with the container, a light source capable of transmitting light into the suspension of microorganisms in the illumination compartment and a circulating device to circulate the suspension of microorganisms between the container and the illumination compartment.
The illumination compartment can be opaque or transparent, of metal, glass or plastics materials and can be entirely transparent or translucent, or can have regions that are opaque, for example, steel regions, with windows of transparent or translucent areas between the opaque regions . Completely transparent illumination compartments are preferred to mixed opaque - transparent. The illumination compartment can have the light source emitting light into the culture through the wall of the compartment, but the light source can be outside or inside the tube as desired. Preferred embodiments have the light source inside the illumination compartment, as this arrangement results in a simpler light path geometry and hence lower light transmission loss compared to the situation if the light source was located outside the illumination compartment, shining inwards. Certain illumination compartments can be made from steel or other non-transparent metals, and can be provided with an inner light source to illuminate the cells from within the compartment. Therefore, the illumination compartment does not need to have any window regions through which light can penetrate, but this remains a preferred option.
The illumination compartment typically comprises an elongate tube, typically of shallow depth or diameter e.g.l-5cm.
The illumination compartment preferably has a lightpath (path from plane of light entrance to opposite wall) equal to the light penetration depth of culture of normal operating condition cell density, e.g. 5-20 cm. and it can preferably include folds, baffles and/or bends to enable the compartment to be accommodated in a small space in order to save room, and to agitate the cells passing through it. The penetration depth of light in the culture is the depth under which the light intensity is below the compensation point of the algal culture, which of course will vary with species and condition.
A practical value of the penetration depth is therefore the depth under which the light intensity is less than 10 μE/m2/sec. The light compartment is typically at least partially of arcuate or circular cross-section, but this is optional, and other cross- sections can be used, such as square, flat, or other complex shapes engineered to enhance flow characteristics and light penetration as desired.
The flow pattern in the illumination compartment is preferably not laminar, but turbulent. This may be accomplished by dimensioning the compartment to have a sufficiently high Reynolds number. At Reynolds numbers higher than 2300 the flow ceases to be laminar and starts assuming a turbulent pattern. Reynolds numbers higher than 10000 are preferred. The cells thereby avoid photo damage caused by extended exposure to high light intensities encountered at the surfaces of the compartment, nearest the light sources. The transition, however, is not entirely predictable only from the Reynolds number, and in hydraulically smooth compartments, flow could be laminar at Reynolds numbers higher than 2300.
To avoid this, the inner surface of the illumination compartment can be adapted to enhance the turbulent character of the flow, by having baffles or ridges etc. Reducing the flow path will increase the Reynolds number and hence increase the turbulent character of the flow. In versions of the illumination compartment having the light source internally, e.g. the light sources and the compartment being concentric, the light source may itself add to the turbulent character of the flow.
Large scale versions of the reactor can be made at comparatively low cost in which the illumination compartment may be isolated, cleaned, steam-sterilised and put into operation again without compromising the sterility of the culture in the main tank, The conventional wells with internal lighting require a complete cessation of the reactor for cleaning or maintenance.
One advantage of our system is that the illumination compartment typically allows illumination of the culture through small glass areas relative to the volume of the culture, high light flux through the transparent areas of the illumination compartment, and short exposure cycles that do not subject the cells to damage through the high light intensities. The entire culture is typically illuminated in short light exposure cycles (e.g. 30 seconds or less) as it passes through the illumination compartment, followed by a longer dark period e.g. 10 minutes and less) as it circulates through the main tank. In this way, the cells receive a high light dose while passing through the illumination compartment or "light loop", and use up the energy received while circulating in the main container.
More illumination compartments can also be added to an existing reactor allowing a scale up of the reactor capacity without substantial re-engineering.
A good light source comprises metal halide lamps, high pressure sodium lamps but other high intensity discharge lamps may be used, especially those that mimic natural daylight. The construction of the illumination compartment can be made to allow exchange of lamps without interrupting the culture flow in the compartment .
In certain embodiments with the internal light source in the tube, all light radiating from the light source inside the tube enters the culture flowing over the surface of the glass tube. This optical arrangement means that the light transmission losses between light source and culture are substantially reduced or eliminated, which otherwise can be substantial, i.e. 50% or more in certain light reflector systems. Light intensities entering the culture over the area of the glass tube can be very high: up to 10000 μE/m2/sec, and typically 4-5000 μE/m2/sec.
The cell density and the flow rate of microorganisms through the illumination compartment is typically carefully controlled. The flow rate is typically adjusted to avoid illuminating the microorganisms beyond their capacity to convert and store the absorbed light energy.
Embodiments of the invention offer the possibility of using very high intensity light sources and controlled exposure times to the light and darkness, ensuring a high degree of utilization of the light flux compared to known reactors, including tubular reactors.
A suitable tubular reactor for use as an illumination compartment is disclosed by Pirt et al in J. Chem. Tech. Biotechnol., 1983. 33B, 35-58, which is herein incorporated by reference. This reactor may use light in an intensity corresponding to natural sunlight (2000 μE πf2 sec"1) over a short lightpath (1 cm) under which conditions the biomass may reach high densities while the concomitant light utilization efficiency is low. (About 90W/m2 were reported absorbed by cells in the reactor at full sunlight intensity which is 900 W/m2 or 2000 μE/m2/sec. At an absorption of 90 W/m2 , the light that enters the culture can be absorbed by a biomass density of 22 g D.W. per litre, although densities of around 8-16g DW/1 may be beneficial.
The main container typically also has a light source, which illuminates the cells in the main container, optionally at a much lower total flux (e.g. 20%) as compared with the light loop. We have found that it is beneficial to provide a low intensity background illumination in the dark phase and this is typically done by lights illuminating the larger reactor through windows in tank walls and/or glass wells immersed in the suspension of cells in the container. Vertical light wells like this are well known and a suitable design is found in US3986297, which is incorporated herein by reference. Beneficial effects are achieved in the growth rate of cells when background illumination is provided in the reactor even at low levels, and without wishing to be bound by theory, we believe that this is related to the lower light levels activating or sustaining the action of light inducible enzymes in the acetate metabolism pathway or ribulose diphosphate carboxylase or other enzymes involved in either pathway.
The invention also provides a method of growing photosynthetic microorganisms in suspension, the method comprising circulating the suspension of microorganisms between a main container and an illumination compartment, wherein the microorganisms are illuminated at high intensity in the illumination compartment, for example, at higher intensities than those which prevail in the main container.
When the cells first enter the illumination compartment, the cellular pools of photosynthetically produced metabolites, such as chloroplastic ATP and NADPH will be low as a result of staying in the dark for extended periods. The cells will therefore be able to assimilate and store relatively large amounts of photosynthetic energy during the light cycle in the illumination tube. They then pass into the main container where later steps of the photosynthesis takes place - initially during exhaustion of the photosynthetically provided pools of ATP and NADPH, then, after depletion of these pools, using ATP and NADH generated by respiration. The illumination compartment is typically illuminated at an intensity of 5-10 mE m"2 sec"1 at the glass interface. Opposite to the glass interface the light intensity can be reduced to very low levels (less than 5-10 μE m"2 sec"1) .
The cells are typically illuminated along the entire length of the compartment for the time that it takes for the cell to pass through i.e. the hydraulic residence time. This can be in the order of 10-60 seconds. The dimensions of the illumination compartment and flow rate between the main tank and the illumination compartment can be adjusted to provide a suitable residence time. For example, for an illumination compartment made of steel with a central glass tube in which the lamps are situated, suitable dimensions for example could be: X = light path = 100 mm L - length of glass tube, = 3 m D2 = width of steel tube = 432 mm Di '= width of glass tube = 232 mm V = Volume of glass tube = 300 L
Residence time in compartment t = 20 sec.
The corresponding Reynolds number, R = p * V Dh μ Dh (geo. diameter) = ((DD22 2- D-,-2-) = 0 . 20
( Dx + D2 )
p = density, = 1000 kg/m3 μ = dynamic visco ossiittyy = 0 . 001 (water at 20°C V = velocity of ffllooww = 0 . 15 m/ s R — 3 0 000
The corresponding flow rate is = 900 L/min.,
Embodiments of the invention will now be described by way of example and with reference to the accompanying drawing Fig. 1, which is a schematic view of a reactor.
Referring now to the drawing, a bioreactor has a main reactor tank 1 with a mechanical stirring device such as an impeller 2 which agitates a suspension of algal cells in the reactor tank 1. The tank has an oxygen electrode 5 which feeds back levels of oxygen to the controller of the impeller 2, and a pH electrode 6 to indicate and potentially control the pH of the cell suspension. In some embodiments the impeller 2 drives the fluid in the tank 1 through an outlet 10 of the tank 1 via feeding pipe 16 into the illumination compartment, shaped for example as an elongate steel tube 20 of diameter e.g. 20-40 cm. However, in this embodiment, the impeller 2 is used only for stirring the main tank and the cells are driven through the light loop by a pump, for example a pump 15. If the pump 15 is an air-lift pump it can drive the fluid from the tube 20 back to the main ank 1 s the photosynthetic energy conversion in the tube 20 ay be more efficient as a result of oxygen, depletion taking place in the main tank l. Oκygeα control in tan 1 i iay be iπpleinented through control f the impeller 2. The tube 20 may surround a transparent glass or plastics tube 22. The glass tube 22 may extend through the length of the tube 20 and transmits light fron light sources shi ing into the bore of the tube 22 ;;rom a very high intensity light source 25-
The light sources AΆ be of any intensity of more than 4 m>3 m"3 sec"1, typically from 4-10 mE "2 sec"1" . Lower intsnsities can also be used. The glass tube 22 in this example has a length > 3 m and a diamet r of > 0.2 m e.g. 225mm diameter. The diameter of the light loop tube 20 is typically 0.234 m.
The combination of tube diameter and lamp flux reduces the intensity of the light at the tube glass surface to the maximum desired value (e.g. 10,000 E M-2 sec-1) sir.iple geometric "dilution". For example, if the maj-imum desired intensity at the glass tube surface is 5 nE m-2 sec-1 and the total flux of the light installation is 500 E day-1 and the length of the gl.ss tube is 3 m, assuming equal distribution of li'jht intensity at the glass tube surface, the light flux rate per secon is 500 / {24 x 3600) = 57S7 μE ser-1; area of glass tube is 5787 /5000 « 1.15 2; diameter of glass tube hence is 1.15 /(3 x PI) = 0.12 M. The useful range of light intensity is 2-10000 μE M-2 sec-1, and is typically >400ό μE M-2 sec-1.
With a transparent tube 20, the light source 25 i-j typically placed outside the tube 20, and the trarsparent tube, 22 can therefore be omitted.
A glass tube 3 ma be placed in che reactor allowing a light source 4 to illuminate the reactor from within. The intensity and total flux of this light source is generally much less than the light source 25, typically 10-25%.
By rotating around flanges 13, the tube 20 may be posr.tioned either horizontally or vertically. The hor:.2ontal position is preferred as the light source 25 nay be easily removed from the tube 25, or for filXing and venting the tube 20,
The cells are driven through the annulus between the ou 'ϊ* tube 20 and the inner glass tube 22 in a state of .urbulent flow. This flow may be established by inj'≥cting air at a low point into a vertical tube 15. This tube therefore functions as the riser of an air l±t z pump. The air is vented from the system through a gas escape 7 from the headspace of reactor tank 1. Caroon dioxide may be added to the air for control of pH. 1 The annulus between the tube 22 and 20 is typically 5-
2 20cπ* in depth, and the cells flow through the tube 20
3 itt a residence time of 10-40 seconds. The light
4 source 25 is rated to meet the photosynthetic light
5 requirements of the culture while the light source 4
6 is rated only to keep the light controlled enzyme
7 systems activated during the residence in the
8 otherwise dark main cylinder. 9
10 As the cells are moving in turbulent flow in the 1 annuluε, the amount of light each, particular cell
12 receives during the passage saturates its light
13 harzesting pathways, but the turbulent flow and brief
14 ss g through the illumination compartment 20
15 reduces the amount of photo-damage experienced by any IS particular cell. The ligh -saturated cells ret irn to
17 the reactor 1 and photosynthesis o£ the cells therein
18 continues until the light energy loaded into the cells 2.9 while in the light loop is exhausted, at which point
20 the cells continue to grown under dark phase
21 respiration or other normal dark phase mechanisms. 2 3 Modifications and improvements can be incorporated 4 wi hout departing from the scope of the invention.

Claims

Claims 1 Apparatus for growing microorganisms, the apparatus comprising a container for cultivation of suspended microorganisms, an illumination compartment in fluid communication with the cor-tainer, a light source capable of transmitting light into the suspension of microorganisms in the il.Xumination compartment and a circulating device to circulate the suspension of microorganisms between th container and the illumination compartment.
2 Apparatus as claimed in claim l wherein the ilLumination compartment is translucent or t ansparent -
3 Apparatus as claimed in claim l, wherein the illumination compartment has regions that are translucent or transparent, and regions that are Ofague .
4 Apparatus as claimed in any preceding claim, wherein the microorganisms are illuminated from w:.thin the illumination compartment.
5 Apparatus as claimed in any preceding claim, where n the illumination compartment comprises an elongate tube.
6 Apparatus as claimed in claim 5, wherein the tube has a diameter of 100-500mm.
7 Apparatus as claimed in claim 5 or claim (>' , 1 wherein the tube is at least partially of arcuate or
2 ciicular cross-section. 3
4 8 Apparatus as claimed in any preceding claim,
5 wherein the illumination compartment introduces
6 fo'-ds, baffles and/or bends in the p&th of the cells
7 pat.sing through the compartment . β
9 9 Apparatus as claimed in any preceding claim, 0 wherein the light source comprises a metal halide 1 l p. 2 3 10 Apparatus as claimed in any preceding claim, 4 wherein the light source is arranged inside a 5 tubular illumination compartment. 6 7 11 Apparatus as claimed in any preceding claim, S wherein the main container is illuminated by a Lower ir.tensity light source than is used in the illumination compartment.
IA' A method of growing photosynthetic microorganisms in suspension, the method comprising circulating the suspension of microorganisms between 5 a main container and an illumination compartment, ≤ a:ιd illuminating the microorganisms at a higher 7 intensity in the illumination compartment than in 8 ie main container. 9 13 A method as claimed in claim 12, wherein the 1 microorganisms are illuminated in the illumination
2 compartment at intensities of between 2-10000
3 μE/m2/sec . 4
5 14 A method as claimed in claim 12, wherein the
6 j croorganiεms are illuminated in the illumination
7 compartment at intensities of between 4-10000
Figure imgf000018_0001
9
10 15 A method as claimed in any oτie of claims 12-14,
11 wnerein the flow pattern in the illumination
12 compartment is turbulent.
13
14 16 A method as claimed in any one of claims 12-15,
15 v-herein the flow of suspension in the illumination
16 compartment has a Reynolds numbers higher than 1000-
17 ;:300.
18
19 .7 A method as claimed in any one of claims 12-16,
20 vherein the microorganisms have a transit time
21 through the illumination compartment of 10-60 ■22 seconds .
23
24 18 A method as claimed in any one of claims 12-17,
25 vherein the microorganisms have a transit time
26 through the main tank of 2-10 minutes- 27
28 19 A method as claimed in any one of claims 12-18,
29 wherein the microorganisms are illuminated along the
30 entire length of the illumination compartment for
31 the time that it takes for the cell to pass through. 32
PCT/GB2002/001800 2001-04-19 2002-04-18 Improvements relating to bioreactors WO2002086053A1 (en)

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DE102004019234B3 (en) * 2004-04-16 2005-11-24 Sartorius Ag Bioreactor for the cultivation of microorganisms
WO2011124727A1 (en) * 2010-04-08 2011-10-13 Acciona Energía, S. A. Optimum energy consumption system for microalgae culture
EP2412793A1 (en) * 2010-07-30 2012-02-01 Kairos Global Co., Ltd. Circulatory photobioreactor
EP2412794A1 (en) * 2010-07-30 2012-02-01 Kairos Global Co., Ltd. Method for circulatory cultivating photosynthetic microalgae
CN102344888A (en) * 2010-07-29 2012-02-08 凯洛斯环球有限公司 Circulating type photobioreactor
CN102344889A (en) * 2010-07-29 2012-02-08 凯洛斯环球有限公司 Method for cyclic culture of photosynthetic microalgae
WO2013095300A1 (en) * 2011-12-19 2013-06-27 Nanyang Technological University Bioreactor
US8658421B2 (en) 2010-07-23 2014-02-25 Kairos Global Co., Ltd. Circulatory photobioreactor
CN109266513A (en) * 2018-08-28 2019-01-25 季华实验室 Brewing apparatus, brewing system and brewing method
CN109259180A (en) * 2018-08-28 2019-01-25 季华实验室 Brewing method, brewing apparatus and brewing system
CN109288022A (en) * 2018-08-28 2019-02-01 季华实验室 Brewing apparatus, brewing system and brewing method

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FR1396350A (en) * 1962-12-20 1965-04-23 Thomson Houston Comp Francaise Improvements to photosynthesis devices
DE1299164B (en) * 1965-05-25 1969-07-10 Busch Plant for continuous algae extraction
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DE102004019234B3 (en) * 2004-04-16 2005-11-24 Sartorius Ag Bioreactor for the cultivation of microorganisms
WO2011124727A1 (en) * 2010-04-08 2011-10-13 Acciona Energía, S. A. Optimum energy consumption system for microalgae culture
US8658421B2 (en) 2010-07-23 2014-02-25 Kairos Global Co., Ltd. Circulatory photobioreactor
CN102344888B (en) * 2010-07-29 2014-08-20 凯洛斯环球有限公司 Circulating type photobioreactor
CN102344888A (en) * 2010-07-29 2012-02-08 凯洛斯环球有限公司 Circulating type photobioreactor
CN102344889A (en) * 2010-07-29 2012-02-08 凯洛斯环球有限公司 Method for cyclic culture of photosynthetic microalgae
EP2412793A1 (en) * 2010-07-30 2012-02-01 Kairos Global Co., Ltd. Circulatory photobioreactor
EP2412794A1 (en) * 2010-07-30 2012-02-01 Kairos Global Co., Ltd. Method for circulatory cultivating photosynthetic microalgae
WO2013095300A1 (en) * 2011-12-19 2013-06-27 Nanyang Technological University Bioreactor
US9930842B2 (en) 2011-12-19 2018-04-03 Nanyang Technological University Bioreactor
CN109266513A (en) * 2018-08-28 2019-01-25 季华实验室 Brewing apparatus, brewing system and brewing method
CN109259180A (en) * 2018-08-28 2019-01-25 季华实验室 Brewing method, brewing apparatus and brewing system
CN109288022A (en) * 2018-08-28 2019-02-01 季华实验室 Brewing apparatus, brewing system and brewing method
CN109259180B (en) * 2018-08-28 2022-07-19 季华实验室 Brewing method, brewing device and brewing system

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