Cluster airlift bioreactor

Abstract

A bioreactor includes a plurality of distributors and a plurality of vertical circulation loops. A first vertical circulation loop of the plurality of vertical circulation loops includes a first distribution region and a first return region. The first vertical circulation loop is in liquid communication with one or more other of the plurality of vertical circulation loops. The first vertical circulation loop is characterized by a separate loop mass transfer coefficient. A controller is coupled to the plurality of distributors and configured to together control the plurality of distributors such that a cumulative mass transfer coefficient of the plurality of vertical circulation loops is within a threshold of an individual loop mass transfer coefficient associated with a first vertical circulation loop.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 334,419, filed on April 25, 2022, entitled “CLUSTER BIOREACTOR,” which is incorporated herein by reference for all purposes, and U.S. Provisional Patent Application No. 63 / 334,423, filed on April 25, 2022, entitled “AIRLIFTING BIOREACTOR,” both of which are incorporated herein by reference for all purposes. Background Art

[0002] As the size of stirred tank bioreactors increases, it becomes increasingly difficult to mix liquids in a bioreactor using a single agitator. As a result, it becomes difficult to provide an ideal environment for cell culture growth. Supplying oxygen to the cells and removing dissolved carbon dioxide (dCO2), a metabolic waste produced by the cells, are also more challenging. Greater distribution requirements are required. By reducing the bubble size, it is possible to reduce the distribution requirements, but smaller bubbles inflict greater damage to the cells than larger bubbles and exacerbate the foaming problem. Most conventional measures to adapt cell cultures to larger stirred tank bioreactors ultimately damage the cells or increase costs, making scaling up bioreactors a challenging task and limiting the scalability of bioreactors.

[0003] Airlift bioreactors are commonly used in microbial fermentation. Protected by a strong cell wall, microorganisms can withstand very high distribution rates and achieve rapid growth and high culture densities. Cells used in cell culture have only a cell membrane to protect them and cannot withstand the high stress from excessive distribution. In order to achieve high cell density, it is critical to minimize distribution while still meeting mass transfer and mixing requirements.

[0004] Airlift designs are known to have inherently low mechanical shear and turbulence, which are beneficial for cell health. However, to increase cell density, a greater amount of distributed air is required to supply oxygen and remove dissolved carbon dioxide. Similar to stirred tank designs, gas distribution in airlift bioreactors negatively affects cell health. As cell density increases, high distribution requirements may stunt cell growth or become detrimental to cell health, setting an upper limit on how high cell density can be achieved in airlift bioreactors.

[0005] Furthermore, the performance of an airlift bioreactor is largely determined by the geometry and aspect ratio of its dimensions. The ratio of the cross-sectional area between the tubes included in the airlift bioreactor and the annulus of the airlift bioreactor and the diameter to height ratio of the tubes are two key design parameters that can affect the efficiency of an airlift bioreactor.

[0006] The volume of an airlift bioreactor used as a riser or downcomer depends on the mode of operation, which can be annularly distributed or tubularly distributed. The riser is typically the volume that is primarily distributed (e.g., the distribution area), while the downcomer is usually the volume that is not distributed or is distributed to a lesser extent (e.g., the return area). Mixing time and mass transfer in an airlift bioreactor are mainly affected by the difference in gas holdup between the riser and downcomer. The difference in gas holdup between the two volumes produces a difference in density that generates a driving force for liquid movement that is proportional to the difference. The liquid recirculation rate in the riser and downcomer affects the overall mixing and mass transfer characteristics of the airlift bioreactor.

[0007] FIG. 1 illustrates an example of an airlift bioreactor. An airlift bioreactor 100 includes a container 101 having a high cylindrical shape and an inner tube 102. A gas 104, such as air, can be distributed inside the inner tube 102 via a distributor 103. The gas-liquid mixture in the inner tube 102 is lighter than the liquid in the annular space, causing the liquid 106 to form a recirculation loop between the inner tube 102 and the annular space. The recirculating flow effectively stirs the bioreactor 100, thereby eliminating the need for an agitator and greatly reducing the cost and risk of contamination. The air can supply oxygen to the cells, and dissolved carbon dioxide (dCO2), a metabolic waste produced by the cells, can be removed via an exhaust pipe 105. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Various embodiments of the invention are disclosed in the following detailed description and accompanying drawings.

[0009] FIG1 illustrates an example of an airlift bioreactor.

[0010] Figure 2A is a side view of a plurality of airlift bioreactors according to some embodiments.

[0011] Figure 2B is a top view of a plurality of airlift bioreactors according to some embodiments.

[0012] Figure 2C is an example of a plurality of airlift tubes housed within a vessel according to some embodiments.

[0013] Figure 2D Depicted is a scaled-up airlift bioreactor according to some embodiments.

[0014] Figure 2E Depicted are examples of containers associated with an airlift bioreactor according to some embodiments.

[0015] Figure 3is a block diagram illustrating a clustered airlift bioreactor according to some embodiments.

[0016] Figure 4A is a flow chart illustrating a process for operating a cluster airlift bioreactor according to some embodiments.

[0017] Figure 4B is a flow chart illustrating a process for operating a cluster airlift bioreactor according to some embodiments.

[0018] Figure 5A is a top view of a cluster airlift bioreactor according to some embodiments.

[0019] Figure 5B is a side view of a cluster airlift bioreactor according to some embodiments.

[0020] Fig. 6A is a top view of a cluster airlift bioreactor according to some embodiments.

[0021] Figure 6B is a side view of a cluster airlift bioreactor according to some embodiments.

[0022] Fig. 7A is a top view of a cluster airlift bioreactor according to some embodiments.

[0023] Figure 7B is a side view of a cluster airlift bioreactor according to some embodiments.

[0024] Figure 8 is a graph comparing mass transfer coefficients associated with individual airlift bioreactors and cluster airlift bioreactors according to some embodiments.

[0025] Fig. 9 is a graph comparing mass transfer coefficients associated with individual airlift bioreactors and cluster airlift bioreactors according to some embodiments.

[0026] Fig. 10A Depicted is a top view of a cluster airlift bioreactor according to some embodiments.

[0027] Fig. 10B Depicted is a side view of a cluster airlift bioreactor according to some embodiments.

[0028] Fig. 10C Depicted is a top view of a cluster airlift bioreactor according to some embodiments.

[0029] Fig. 10D Depicted is a side view of a cluster airlift bioreactor according to some embodiments.

[0030] Fig.11A is a diagram illustrating a dual sparger airlift bioreactor according to some embodiments.

[0031] Fig. 11B is a diagram illustrating a dual sparger airlift bioreactor according to some embodiments.

[0032] Fig. 12A is a diagram illustrating a dual sparger airlift bioreactor according to some embodiments.

[0033] Fig. 12B is a diagram illustrating a dual sparger airlift bioreactor according to some embodiments.

[0034] Fig. 12C is a diagram illustrating a dual sparger airlift bioreactor according to some embodiments.

[0035] Fig.13A is a diagram illustrating a dual sparger airlift bioreactor according to some embodiments.

[0036] Fig. 13B is a diagram illustrating a dual sparger airlift bioreactor according to some embodiments.

[0037] Fig.14A Illustrated is a side view of a dual sparger airlift bioreactor according to some embodiments.

[0038] Fig. 14B A top view of a dual sparger airlift bioreactor is shown, according to some embodiments.

[0039] Fig.15 It is a diagram comparing annularly distributed airlift bioreactor, tubularly distributed airlift bioreactor and dually distributed airlift bioreactor.

[0040] Fig.16 is a block diagram illustrating a system for controlling a dual sparger airlift bioreactor according to some embodiments.

[0041] Fig.17 is a flow chart illustrating a process for utilizing a dual sparger airlift bioreactor according to some embodiments. DETAILED DESCRIPTION

[0042] The present invention may be implemented in a variety of ways, including as: a process; an apparatus; a system; a composition of matter; a computer program product embodied on a computer-readable storage medium; and / or a processor, such as a processor configured to execute instructions stored on and / or provided by a memory connected to the processor. In this specification, these embodiments or any other form that the present invention may take may be referred to as techniques. In general, the order of the steps of the disclosed processes may be changed within the scope of the present invention. Unless otherwise stated, components such as processors or memories described as being configured to perform tasks may be implemented as general components temporarily configured to perform tasks at a given time or as specific components manufactured to perform tasks. As used herein, the term "processor" refers to one or more devices, circuits, and / or processing cores configured to process data (such as computer program instructions).

[0043] Provided below is a detailed description of one or more embodiments of the present invention and drawings illustrating the principles of the present invention. The present invention is described in conjunction with such embodiments, but the present invention is not limited to any embodiment. The scope of the present invention is limited only by the claims, and the present invention encompasses many alternatives, modifications and equivalents. In order to provide a comprehensive understanding of the present invention, many specific details are set forth in the following description. These details are provided for illustrative purposes, and the present invention can be practiced according to the claims without some or all of these specific details. For the purpose of clarity, technical materials known in the technical field related to the present invention are not described in detail so that the present invention is not unnecessarily obscured.

[0044] Airlift bioreactors avoid the complications associated with large agitators in stirred tank bioreactors and provide an attractive solution for scaling up cell culture. Airlift bioreactors can be designed to have specific properties (e.g., mass transfer coefficient, shear turbulence, mixing, etc.). Airlift bioreactors can be scaled up by increasing the size of the container associated with the airlift bioreactor, however, increasing the size of the container can change the performance of the airlift bioreactor. As the size of the airlift bioreactor increases, the specific performance of the airlift bioreactor can be maintained to a certain extent by maintaining the height to diameter ratio of the airlift bioreactor tube and the cross-sectional area ratio between the airlift bioreactor tube and the annulus. However, a drawback of this method is that due to the physical size of the building that accommodates the airlift bioreactor, there is an upper limit to which the airlift bioreactor can be scaled up. The maximum height of the building (e.g., the height of the ceiling) may be reached, which prevents further increase in the volume of the airlift bioreactor without affecting the performance of the airlift bioreactor.

[0045] A cluster airlift bioreactor is disclosed herein. The cluster airlift bioreactor increases the cross-sectional area of ​​a container associated with the airlift bioreactor, and adds multiple tubes within the container. The cluster airlift bioreactor can be used to amplify the performance of a single airlift bioreactor. The performance of a single airlift bioreactor is constant based on the height to diameter ratio of the tube of the airlift bioreactor and the cross-sectional area ratio between the tube and the annulus of the airlift bioreactor. A single airlift bioreactor can be amplified, and the performance associated with a single airlift bioreactor can be maintained within a threshold by the cluster airlift bioreactor by maintaining the tube height to diameter ratio of the single airlift bioreactor and applying the same ratio to all tubes included in the cluster airlift bioreactor and maintaining the sum of the cross-sectional areas of all tubes to the cross-sectional area ratio of the annular area of ​​the container (e.g., the area between the wall of the container and the tube) to match the cross-sectional area ratio between the tube and the annulus of the single airlift bioreactor. The cluster airlift bioreactor can be used to cultivate meat production of mammalian, avian, fish, reptile, crustacean or mollusk cell mass for human or animal consumption. Cluster airlift bioreactors can be used for cellular agriculture of plant cells as an alternative to conventional production. Cluster airlift bioreactors can be used for biopharmaceutical cultivation of rodent, primate and insect cells for the production of cell therapy, gene therapy, antibodies, nanobodies, enzymes, fusion proteins and vaccines.

[0046] Figure 2A is a side view 200 of a plurality of airlift bioreactors according to some embodiments. Figure 2B is a top view 250 of a plurality of airlift bioreactors according to some embodiments. In the example shown, the airlift bioreactors 201, 203, 205, 207, 209 are housed within a building 202. The airlift bioreactor 201 can be scaled up by increasing the size of the vessels associated with the airlift bioreactor 201. As the size of the airlift bioreactor 201 increases to become the airlift bioreactor 203 or the airlift bioreactor 205, the specific performance of the airlift bioreactor 201 can be maintained by maintaining the ratio of the height to the diameter of the tubes and the ratio of the cross-sectional area between the tubes and the annulus constant. Due to the physical size of the building 202, there is an upper limit to how much the airlift bioreactor 201 can be scaled up simply by increasing the size of the vessels. As shown in FIG. Figure 2A As can be seen in FIG. 2 , the height of the airlift bioreactor 205 has reached the height of the building 202 .

[0047] The airlift bioreactor 205 can be further scaled up by increasing the cross-sectional area of ​​the vessel and adding multiple airlift tubes within the vessel. Figure 2A and Figure 2BAs seen in FIG. 1 , airlift bioreactor 207 has increased the volume of the vessel associated with airlift bioreactor 205 and added three additional tubes. Airlift bioreactor 209 has increased the volume of the vessel associated with airlift bioreactor 205 and added six additional tubes. Figure 2A and Figure 2B The airlift bioreactor 205 is depicted scaled up to include 4 and 7 tubes, but the airlift bioreactor 105 may be scaled up to include n tubes (eg, between 3 and 400 tubes). Figure 2D Airlift bioreactor 205 is depicted scaled up to become air reactor 252 (3 tubes) and airlift bioreactor 209 (7 tubes). Airlift bioreactor 205 can be scaled up and performance associated with airlift bioreactor 205 can be maintained within thresholds by maintaining the height to diameter ratio of the individual tubes associated with airlift bioreactor 205 across all tubes of the cluster airlift bioreactor and maintaining the ratio of the sum of the cross-sectional area of ​​all tubes to the cross-sectional area of ​​the annular region of the vessel to match the cross-sectional area ratio between the tubes and annulus of airlift bioreactor 105. Such an example is shown in FIG. Figure 2C , which depicts a plurality of tubes housed within a container 250. In some embodiments, the bottom of the container 250 is flat. In some embodiments, the bottom of the container 250 includes a plurality of concave retainers for the plurality of tubes to facilitate solid suspension of the plurality of tubes. In some embodiments, physical baffles are present between adjacent airlift modules to reduce lateral fluid movement and enhance the vertical flow field. The baffles may impose partial or complete restrictions on liquid movement between modules. In some embodiments, the physical baffles are fins located on the inner sidewall of the container 250. In some embodiments, the physical baffles are fins located on the airlift tubes.

[0048] The container associated with the airlift bioreactor may have a cylindrical shape, a rectangular shape, a triangular shape, a square shape, a pentagonal shape, a hexagonal shape, a heptagonal shape, an octagonal shape, a nonagonal shape, a decagonal shape, or any other shape. Figure 2D A vessel associated with an airlift bioreactor is depicted having a cylindrical shape. Figure 2E A container associated with an airlift bioreactor is depicted having a hexagonal shape. The shape of the container may be selected to better fit with pipes associated with the airlift bioreactor or to better fit with the surrounding environment of the installation location.

[0049] The air lift tubes may have a cylindrical shape, a rectangular shape, a triangular shape, a square shape, a pentagonal shape, a hexagonal shape, a heptagonal shape, an octagonal shape, a pentagonal shape, a decagonal shape, or any other shape. The shapes of the air lift tubes within the container may be different. For example, the air lift tubes near the wall of the container and the air lift tubes in the center may have different shapes.

[0050] Figure 3 314a, 314b, ..., 314n associated with a plurality of vertical circulation loops 315a, 315b, ..., 315n. In some embodiments, the vertical circulation loop includes an ascending pipe portion (e.g., a distribution area) and a descending pipe portion (e.g., a return area). For example, the area within the tube 102 of the airlift bioreactor 100 may correspond to the ascending pipe portion of the vertical circulation loop, and the annular area of ​​the airlift bioreactor 100 may correspond to the descending pipe portion of the vertical circulation loop. In some embodiments, the ascending pipe portion of the vertical circulation loop is inside the container 312, and the descending pipe portion of the vertical circulation loop is outside the container 312. In some embodiments, the riser portion of the vertical circulation loop is outside the vessel 312 , and the downcomer portion of the vertical circulation loop is inside the vessel 312 .

[0051] although Figure 3 The vessel 312 is depicted as including three spargers and three vertical circulation loops, but the cluster airlift bioreactor 300 may include n spargers and n vertical circulation loops. The controller 302 is configured to increase or decrease corresponding distribution rates associated with the plurality of spargers 314a, 314b, ..., 314n.

[0052] The individual vertical circulation loops are characterized by individual loop mass transfer coefficients, mixing times, recirculation flow rates, and bubble residence times. The controller 302 is configured to control the plurality of distributors 314a, 314b, ..., 314n together so that the cumulative mass transfer coefficients of the plurality of vertical circulation loops are within a threshold of individual loop mass transfer coefficients associated with the individual vertical circulation loops. The controller 302 is configured to control the plurality of distributors 314a, 314b, ..., 314n together so that the cumulative mixing times of the plurality of vertical circulation loops are within a threshold of individual mixing associated with the individual vertical circulation loops. The controller 302 is configured to control the plurality of distributors 314a, 314b, ..., 314n together so that the cumulative recirculation flow rates of the plurality of vertical circulation loops are within a threshold of individual recirculation flow rates associated with the individual vertical circulation loops. The controller 302 is configured to control the plurality of distributors 314a, 314b, ..., 314n together such that the cumulative bubble residence time of the plurality of vertical circulation loops is within a threshold of individual bubble residence times associated with the individual vertical circulation loops.

[0053] In some embodiments, the controller 302 controls the distribution rates associated with the plurality of distributors 314a, 314b, ..., 314n to be the same distribution rate. This results in vertical mixing occurring within the plurality of vertical circulation loops 315a, 315b, ..., 315n. When the distribution rates associated with the plurality of distributors 314a, 314b, ..., 314n are the same, some horizontal mixing may occur between the vertical circulation loops 315a, 315b, ..., 315n, however, the primary form of mixing in this embodiment is vertical mixing.

[0054] In some embodiments, the controller 302 controls the distribution rate associated with at least one of the plurality of distributors 314a, 314b, ..., 314n to be different from the other distributors. This results in horizontal mixing occurring within the plurality of vertical circulation loops 315a, 315b, ..., 315n. When introducing additives into the cluster airlift bioreactor, horizontal mixing may be desired to increase the rate at which the additives diffuse throughout the working volume of the cluster airlift bioreactor and to reduce the amount of time required.

[0055] The one or more sensors 311 may include a pH sensor, a temperature sensor, a dissolved oxygen sensor, a dissolved carbon dioxide sensor, a biocapacitive sensor, a Raman spectroscopy sensor, a near-infrared light sensor, and the like.

[0056] The heating element 313 may be used to increase the temperature of the liquid within the container 312 to a desired temperature.

[0057] The cluster airlift bioreactor 300 may include distributors of different configurations. In some embodiments, all distributors 314a, 314b, ..., 314n included in the cluster airlift bioreactor 300 are tubular distributors. In some embodiments, all distributors 314a, 314b, ..., 314n included in the cluster airlift bioreactor 300 are annular distributors. In some embodiments, each of the vertical circulation loops 315a, 315b, ..., 315n is associated with a corresponding tubular distributor and a corresponding annular distributor.

[0058] In some embodiments, some of the vertical circulation loops 315a, 315b, ..., 315n are associated with corresponding tubular distributors, some of the vertical circulation loops 315a, 315b, ..., 315n are associated with corresponding annular distributors, and some of the vertical circulation loops 315a, 315b, ..., 315n are associated with corresponding tubular distributors and corresponding annular distributors.

[0059] Figure 4A is a flow chart illustrating a process for operating a cluster airlift bioreactor according to some embodiments. In the example shown, process 400 may be implemented by a controller such as controller 302 .

[0060] At 402, the distribution rate associated with a plurality of distributors is adjusted to the same distribution rate. Each of the plurality of distributors is connected to a controller, which controls the corresponding distribution rate of the plurality of distributors. Distribution enables mixing in the airlift bioreactor to occur, provides oxygen for cell consumption, and removes carbon dioxide waste produced by the cells. In some embodiments, the vertical circulation loop is associated with a tubular distributor, and the distribution rate associated with the tubular distributor is adjusted. In some embodiments, the vertical circulation loop is associated with an annular distributor, and the distribution rate associated with the annular distributor is adjusted. In some embodiments, the vertical circulation loop is associated with a tubular distributor and an annular distributor, and the distribution rate associated with the tubular distributor and / or the annular distributor is adjusted.

[0061] At 404, the mass transfer coefficient associated with the plurality of distributors is monitored. The cluster airlift bioreactor is designed in such a way that the performance of the cluster airlift bioreactor matches the performance of a single airlift bioreactor within a threshold value. The performance of the airlift bioreactor can be quantified using the mass transfer coefficient. The mass transfer coefficient is a parameter that determines the rate at which a gaseous compound (e.g., O2 or CO2) can be transferred between a gas phase and a liquid phase. The mass transfer coefficient of the cluster airlift bioreactor can be designed to match the mass transfer coefficient of a single airlift bioreactor by maintaining a height to diameter ratio of the tubes included in the single airlift bioreactor for all tubes included in the cluster airlift bioreactor, and maintaining a ratio of the cross-sectional area of ​​the sum of all tubes to the cross-sectional area of ​​the annular region of the container (e.g., the region between the wall of the container and the tubes) to match the cross-sectional area ratio between the tubes and the annulus of the single airlift bioreactor.

[0062] When multiple distributors are in operation, the mass transfer coefficients associated with multiple distributors are calculated in real time. Mass transfer between gas-liquid interfaces is well known. The mass transfer behavior of bubbles rising in liquids can be solved using ordinary differential equations (ODEs). The equivalent mass transfer coefficient can be calculated by how much oxygen is successfully transferred from the gas phase to the liquid phase.

[0063] At 406, it is determined whether the monitored mass transfer coefficient is within a threshold of an expected mass transfer coefficient. The expected mass transfer coefficient corresponds to a mass transfer coefficient associated with a single airlift bioreactor. The cumulative mass transfer coefficient associated with the plurality of spargers may be increased by increasing a distribution rate associated with the plurality of spargers.

[0064] In response to determining that the monitored mass transfer coefficient is within the threshold of the expected mass transfer coefficient, process 400 proceeds to 408. In response to determining that the monitored mass transfer coefficient is not within the threshold of the expected mass transfer coefficient after the specified time period, process 400 returns to step 402.

[0065] At 408, the distribution rates associated with the plurality of spargers are maintained until the cell culture batch is complete.

[0066] Figure 4B is a flow chart illustrating a process for operating a cluster airlift bioreactor according to some embodiments. In the example shown, process 450 may be implemented to control pH by a controller, such as controller 302 .

[0067] At 452, it is determined that a pH reading associated with a bioreactor is not at a set point.

[0068] At 454, a gas profile or liquid additive is introduced into the bioreactor. The bioreactor includes a liquid having an associated pH. The introduction of the additive or gas profile can be used to maintain a pH set point. The additive can be introduced into the bioreactor to adjust the pH associated with the bioreactor in one direction. In some embodiments, the additive is a base for increasing the pH. In some embodiments, the additive is an acid for reducing the pH. In some embodiments, the gas profile has a high nitrogen concentration (e.g., greater than a nitrogen concentration threshold) to increase the pH. In some embodiments, the gas profile has a high carbon dioxide concentration (e.g., greater than a carbon dioxide threshold) to reduce the pH. In some embodiments, the liquid additive is an inoculant (e.g., a cell culture medium associated with a plurality of cells).

[0069] At 456, the distribution rate associated with at least one of the plurality of distributors is adjusted. The distribution rate associated with at least one of the plurality of distributors is adjusted to be different from one or more other distributors. This results in horizontal mixing occurring within the cluster airlift bioreactor. Horizontal mixing may be desirable when an additive needs to be rapidly dissipated throughout the cluster airlift bioreactor so that the additive does not remain in a localized area of ​​the cluster airlift bioreactor for a long period of time.

[0070] In some embodiments, a plurality of vertical circulation loops are associated with corresponding tubular distributors, and the distribution rate associated with at least one of the tubular distributors is adjusted. In some embodiments, a plurality of vertical circulation loops are associated with corresponding annular distributors, and the distribution rate associated with at least one of the annular distributors is adjusted. In some embodiments, a plurality of vertical circulation loops are associated with corresponding tubular distributors and corresponding annular distributors. The distribution rate associated with both the tubular distributor and the annular distributor of at least one of the plurality of vertical circulation loops is adjusted.

[0071] At 458, a pH level associated with a liquid contained in the bioreactor is monitored. The pH level associated with the liquid is monitored for a specified amount of time.

[0072] At 460, after the pH level associated with the liquid has been monitored for a specific amount of time, it is determined whether the pH level associated with the liquid is consistent. The bioreactor includes multiple pH sensors located at different locations throughout the bioreactor. The fact that the pH level associated with the liquid is consistent (e.g., the readings of the pH sensors are equal) indicates that the gas or liquid additive has been evenly distributed throughout the bioreactor. The fact that the pH level associated with the liquid is inconsistent indicates that the gas or liquid additive is not evenly distributed throughout the bioreactor. In response to determining that the pH level associated with the liquid is consistent, process 450 proceeds to 462. In response to determining that the pH level associated with the liquid is inconsistent, process 450 returns to 456. In some embodiments, in response to determining that the pH level associated with the liquid is inconsistent, process 450 returns to 458.

[0073] At 462, it is determined whether the current pH matches the set point pH. After the additive is added to the bioreactor, the liquid is expected to have a specific pH. The expected pH value is established as the set point pH. In response to determining that the pH level associated with the liquid matches the set point pH, the process 450 proceeds to 464. In response to determining that the pH level associated with the liquid does not match the set point pH, the process 450 returns to 454.

[0074] At 464, the distribution rate associated with at least one of the plurality of spargers is modified to a default distribution rate. The distribution rate associated with at least one of the plurality of spargers is modified to be the same as the distribution rate associated with one or more other spargers included in the cluster airlift bioreactor. This changes the mixing state of the cluster airlift bioreactor from horizontal mixing to vertical mixing.

[0075] Figure 5A is a top view of a cluster airlift bioreactor according to some embodiments. Figure 5B5 is a side view of a cluster airlift bioreactor according to some embodiments. In the example shown, the controller 302 is connected to the container 512 of the cluster airlift bioreactor 500 via distributors 514a, 514b, 514c, 514d. In some embodiments, the controller 302 is configured to increase or decrease the distribution rate associated with one of the distributors 514a, 514b, 414c, 414d individually. In some embodiments, the controller 502 is configured to increase or decrease the distribution rate associated with the distributors 514a, 514b, 514c, 514d inside the container 512 (e.g., the distribution area) in common. Each of the distributors 514a, 514b, 514c, 514d is associated with a corresponding external airlift tube 515a, 515b, 515c, 515d. In some embodiments, the external airlift tubes 515a, 515b, 515c, 515d correspond to the downcomer portion (e.g., return region 515) of the corresponding vertical circulation loop. In some embodiments, the external airlift tubes 515a, 515b, 515c, 515d correspond to the upcomer portion of the corresponding vertical circulation loop. Mounting the airlift tubes 515a, 515b, 515c, 515d outside the container 512 enables easy cleaning of the cluster airlift bioreactor. Although the cluster airlift bioreactor 500 is depicted as having four airlift tubes, the cluster airlift bioreactor 500 may include n airlift tubes.

[0076] Fig. 6A is a top view of a cluster airlift bioreactor according to some embodiments. Figure 6B614a, 614b, 614c, 614d are associated with a corresponding external airlift tube 615a, 615b, 615c, 615d. In some embodiments, the external airlift tubes 615a, 615b, 615c, 615d correspond to the downcomer portion of the corresponding vertical circulation loop. In some embodiments, the external airlift tubes 615a, 615b, 615c, 615d correspond to the upcomer portion of the corresponding vertical circulation loop. Although the cluster airlift bioreactor 600 is depicted as having four airlift tubes, the cluster airlift bioreactor 600 may include n airlift tubes. The cluster airlift bioreactor 600 is similar to the cluster airlift bioreactor 500, except that the external airlift tubes 615a, 615b, 615c, 615d are rectangular in shape rather than cylindrical in shape.

[0077] Fig. 7A is a top view of a cluster airlift bioreactor according to some embodiments. Figure 7B It is a side view of a cluster airlift bioreactor according to some embodiments. Some of the external loops can be closed at the beginning of a batch, and opened one by one during the batch. This design supports the fed-batch cell culture when the filling level does not have a large change. In the example shown, the controller 302 is connected to the container 712 of the cluster airlift bioreactor 700 via a distributor 714. The controller 302 is configured to increase or decrease the distribution rate associated with the distributor 714. The distributor 714 is associated with a plurality of external airlift pipes 715a, 715b, 715c, 715d, 715e. In certain embodiments, the external airlift pipes 715a, 715b, 715c, 715d, 715e correspond to the downcomer portion of the corresponding vertical circulation loop. In certain embodiments, the external airlift pipes 715a, 715b, 715c, 715d, 715e correspond to the upcomer portion of the corresponding vertical circulation loop.

[0078] Figure 8is a graph comparing mass transfer coefficients associated with a single airlift bioreactor and a cluster airlift bioreactor according to some embodiments. In the example shown, graph 800 compares the performance of a single airlift bioreactor including a single airlift tube having a specific height to diameter ratio of the tube and a cross-sectional area ratio between the tube and the annulus with the performance of a cluster airlift bioreactor having four airlift tubes having a specific height to diameter ratio of the tube and a ratio of the sum of the cross-sectional areas of all tubes to the cross-sectional area of ​​the annulus that matches the cross-sectional area ratio between the tube and the annulus of the single airlift bioreactor. Graph 800 illustrates that as the distribution rate of the airlift bioreactor increases, the mass transfer coefficient of the single airlift bioreactor and the mass transfer coefficient of the cluster airlift bioreactor both increase and are within a threshold of each other. When both airlift bioreactors are annularly distributed, the performance of the cluster airlift bioreactor slightly outperforms the performance of the single airlift bioreactor.

[0079] Fig. 9 is a graph comparing mass transfer coefficients associated with a single airlift bioreactor and a cluster airlift bioreactor according to some embodiments. In the example shown, graph 900 compares the performance of a single airlift bioreactor including a single airlift tube having a specific height to diameter ratio of the tube and a cross-sectional area ratio between the tube and the annulus with the performance of a cluster airlift bioreactor having four airlift tubes having a specific height to diameter ratio of the tube and a ratio of the sum of the cross-sectional areas of all tubes to the cross-sectional area of ​​the annulus that matches the cross-sectional area ratio between the tube and the annulus of the single airlift bioreactor. Graph 900 illustrates that as the distribution rate of the airlift bioreactor increases, the mass transfer coefficient of the single airlift bioreactor and the cumulative mass transfer coefficient of the cluster airlift bioreactor both increase and are within a threshold of each other. However, in contrast to graph 800, when both airlift bioreactors are tubularly distributed, the performance of the single airlift bioreactor slightly outperforms the performance of the cluster airlift bioreactor.

[0080] Figure 8 and Fig. 9The differences in performance depicted in can be explained by the different bore sizes used for the distributors. This difference results in different bubble sizes, which affects the mass transfer coefficient. In the annular distribution mode, the cluster airlift bioreactor improves mass transfer over a range of distribution rates. In the tubular distribution mode, the performance of the single airlift bioreactor is better than the cluster airlift bioreactor. Table 1 lists the characteristics associated with the single airlift bioreactor and the cluster airlift bioreactor that produced the results of graphs 800, 900. alone Cluster Volume(L) 16 67 Annulus radius (inches) 2.5 5 Number of tubes 1 4 Liquid height (inches) 52 52 Table 1

[0081] Fig. 10A Depicted is a top view of a cluster airlift bioreactor according to some embodiments. Fig. 10B Depicts a side view of a cluster airlift bioreactor according to some embodiments. In the example shown, the cluster airlift bioreactor 1000 includes a corresponding tubular sparger located in the center of each of the tubes. Gas is supplied to each of the tubular sparger 1003a, 1003b, 1003c, 1003d from one or more gas supply lines 1013a, 1013b.

[0082] Fig. 10C Depicted is a top view of a cluster airlift bioreactor according to some embodiments. Fig. 10D A side view of a cluster airlift bioreactor according to some embodiments is depicted. In the example shown, the cluster airlift bioreactor 1050 includes corresponding annular distributors surrounding the tubes. Gas is supplied to each of the annular distributors 1054a, 1054b, 1054c, 1054d from one or more gas supply lines 1063a, 1063b.

[0083] In some embodiments, a dual-sparger airlift bioreactor is used, and the tubes of the cluster airlift bioreactor are both tubularly distributed and annularly distributed.

[0084] Because the airlift bioreactors disclosed herein do not have agitators, they also significantly reduce the costs and contamination risks associated with agitators, making them an attractive alternative to stirred tank bioreactors.

[0085] Fig.11A1 is a diagram illustrating a dual sparger airlift bioreactor according to some embodiments. The dual sparger airlift bioreactor 1100 includes a container 1101 and an inner tube 1102 having a specific shape. The container 1101 may have a cylindrical shape, a rectangular shape, a triangular shape, a square shape, a pentagonal shape, a hexagonal shape, a heptagonal shape, an octagonal shape, a pentagonal shape, a decagonal shape, or any other shape. A first gas such as oxygen may be introduced into the dual sparger airlift bioreactor 1100 through a first manifold 1106 and distributed inside the inner tube 1102 via a sparger 1103. The sparger 1103 supplies the oxygen required for cells to remain alive and grow. A second gas such as air may be introduced into the dual sparger airlift bioreactor 1100 through a second manifold 1105 and distributed in the annular space via a sparger 1104. The air is primarily used to remove dCO2 from the culture; it also supplements some oxygen for the cells. The double sparger airlift bioreactor 1100 maximizes oxygen transfer efficiency without a net increase in distribution rate, and is capable of achieving high-density cell culture under mild conditions for better cell health. The double sparger airlift bioreactor 1100 can be used to culture meat production of mammalian, bird, fish, reptile, crustacean, and mollusk cell groups for human or animal consumption. The double sparger airlift bioreactor 1100 can be used for cell agriculture of plant cells to replace conventional production. The double sparger airlift bioreactor 1100 can be used for biopharmaceutical culture of rodents, primates, and insect cells for cell therapy, gene therapy, antibodies, nanobodies, enzymes, fusion proteins, and vaccine production. The double sparger airlift bioreactor 1100 effectively utilizes the distribution gas and strikes a good balance between two competing goals (i.e., low stress on cells and good mass transfer / mixing). The double sparger airlift bioreactor 1100 also reduces energy consumption and gas costs.

[0086] In order to have good liquid circulation and mixing time, the diameter of the airlift tube 1102 should be between 0.5 and 0.85 of the inner diameter of the airlift section of the dual-sparger airlift bioreactor 1100. In other words, if the airlift bioreactor is not completely cylindrical, the airlift tube cross-sectional area should be between 25% and 72% of the cross-sectional area of ​​the bioreactor. Note that if the bioreactor has a wider bubble separator section, this range does not apply to the wider bubble separator section. The height of the airlift tube 1102 can be between 2-40 feet to take advantage of the benefits described herein. The lower end of 2 to 20 feet is ideal for bioreactors with sintered or small drilled hole distributors in the downcomer; while the higher end of 10 to 40 feet is ideal for bioreactors with drilled or open pipe distributors in the downcomer.

[0087] In any bioreactor, cells require nutrients from cell culture medium. In certain embodiments, cells are mammalian cells, bird cells, fish cells, reptile cells, crustacean cells or mollusk cells. In certain embodiments, cells are plant cells. In certain embodiments, cells are rodent cells, primate cells or insect cells. In addition, cells also consume oxygen and produce carbon dioxide. As a metabolic waste, excessive accumulation of carbon dioxide can damage cell health and acidify the culture medium. Note that moderate levels of dissolved carbon dioxide are acceptable and even beneficial to maintaining the pH of the cell culture medium. Carbon dioxide can be removed from the dual distributor airlift bioreactor 1100 via exhaust pipe 1107.

[0088] In an airlift bioreactor, the distribution gas has three main functions: 1) to provide good mixing; 2) to provide oxygen for cell consumption; 3) to remove carbon dioxide waste produced by the cells. The distribution gas drives the liquid circulation loop between the riser, downcomer, and the two sections above and below the airlift. Rapid liquid circulation leads to good mixing and minimizes uneven distribution of nutrients, oxygen, carbon dioxide, metabolic waste, titrants, and temperature. Oxygen and carbon dioxide have very different solubilities and Henry's coefficients. As a result, their mass transfer behaviors in cell culture are significantly different.

[0089] In order to make the double sparger airlift bioreactor 1100 work effectively, the two sparger play different roles. The distribution gas flow rate delivered by one sparger is significantly higher than that of the other. It drives liquid recirculation and mixing. The liquid rises in the area above the sparger, so the area is called the riser. In the riser, the distribution gas can be different mixtures at different stages of cell culture: nitrogen / air / CO2 mixtures at lower stages, air at high-density stages, or air / oxygen mixtures for ultra-high-density stages. Another sparger delivers a much smaller distribution flow rate. It generates some lifting power, but cannot compete with the sparger in the riser. The liquid sinks in this area, so it is called the downcomer. In the downcomer, the distribution gas can be oxygen-enriched gas or pure oxygen. In some embodiments, the sparger gas flow rate delivered by sparger 1104 is significantly higher (e.g., larger than a threshold amount) than sparger 1103. In some embodiments, the sparger gas flow rate delivered by sparger 1103 is significantly higher than that of sparger 1104. The dual sparger design takes advantage of the different hydraulic characteristics of the riser and downcomer and matches them to the oxygen transfer and carbon dioxide removal requirements.

[0090] In the riser, the bubble residence time is short due to the high combined velocity of the rising bulk liquid and the rising of the bubbles due to buoyancy. The high flow rate and short residence time make it ideal for playing a leading role in carbon dioxide removal. In the downcomer, the bubbles rise relative to the bulk liquid. By balancing them carefully, the bubbles can have a much longer residence time, which is very helpful in promoting oxygen transfer. As a result, less distribution gas is needed to achieve the same oxygen transfer requirements. This is particularly important when trying to achieve high cell density.

[0091] Note that the distribution in the riser also contributes to oxygen transfer, and similarly the distribution in the downcomer also contributes to carbon dioxide removal. Their contributions are not negligible, just relatively non-dominant.

[0092] By separating oxygen transfer and carbon dioxide removal, the dual sparger design not only uses gas efficiently for oxygen transfer and carbon dioxide removal (thus, minimizing cell damage caused by unnecessarily high sparger flow rates), but also decouples the dissolved oxygen control loop from the dissolved carbon dioxide control loop in the bioreactor automation scheme. The decoupling of these two requirements simplifies automation, allows greater freedom in cell culture process design, eliminates the dilemma of dealing with competing goals, and removes a major obstacle that hinders the achievement of high cell densities. The control of dissolved gas concentration is mainly affected by mass transfer and is limited by mass balance. Mass transfer depends on the surface area, the concentration difference between the gas phase and the liquid phase, and the time available for mass transfer (bubble residence time).

[0093] Mixing time and mass transfer in an airlift bioreactor are primarily affected by the difference in gas holdup between the riser and downcomer. When there is a difference in gas holdup between the two volumes, the difference creates a difference in density that generates a driving force for liquid movement that is proportional to the difference. The liquid velocity in the riser and downcomer affects the bioreactor mixing time and the bubble residence time. The bubble residence time has a direct impact on mass transfer efficiency.

[0094] For typical cell culture, the bioreactor requires many times more air and / or nitrogen flow rates than the oxygen demand to remove dCO2. Therefore, the air-liquid mixture in the annulus of the dual sparger airlift bioreactor 1100 will be much lighter than the oxygen-liquid mixture in the inner tube 1102. When compared to the recirculation flow depicted in FIG. 1, Fig.11AThe recirculating flow depicted in FIG. flows in the opposite direction. The liquid (e.g., cell culture medium) descends in the inner tube 1102 and hinders the rising oxygen bubbles. The oxygen bubbles will be slowed down or trapped in the inner tube 1102. The increased residence time of the oxygen bubbles in the inner tube will greatly enhance mass transfer. Smaller oxygen bubbles will shrink in size quickly or even completely dissolve in the liquid. As a result, oxygen utilization can be greatly improved, even approaching the theoretical limit (i.e., all input oxygen is consumed by cells). High oxygen transfer efficiency reduces oxygen demand and minimizes cell damage caused by oxygen bubble rupture when the oxygen bubbles reach the liquid surface 1108. The double sparger airlift bioreactor design enables high-density cell culture while maintaining mild conditions for the cells, solving the great challenges faced by the scale-up of conventional stirred tanks and airlift bioreactors. The optimal aspect ratio of the airlift tube height to its inner diameter is between 5-10. The liquid height 1108 from the bottom of the airlift tube to the bottom of the bioreactor should be anywhere between 0.25 and 1.0 of the inner diameter of the airlift tube. The lower end of 0.25-0.5 is ideal for cell culture in the form of aggregates and microcarriers; while the higher end of 0.35-1.0 is ideal for suspension cell culture.

[0095] Using counter-flow to slow or capture oxygen bubbles, the dual distribution airlift bioreactor 1100 and its variations promote oxygen mass transfer and minimize distribution requirements, thereby creating a healthy environment for cell growth and proliferation. These airlift bioreactors overcome one of the major barriers preventing high cell densities in large bioreactors.

[0096] The designation of risers and downcomers is determined by operating conditions, not hardware. One can switch roles by adjusting the distribution flow rates. For example, Fig. 11B The double sparger airlift bioreactor 1100 is shown, wherein when Fig.11A When compared to the dual-sparger airlift bioreactor of FIG1100, the roles of the riser and downcomer have been reversed. A first gas, such as air, is introduced into the dual-sparger airlift bioreactor 1100 through the first manifold 1106 and distributed inside the inner tube 1102 via the sparger 1103. Air is primarily used to remove dCO2 from the culture; it also supplements some oxygen for the cells. A second gas, such as oxygen, is introduced into the dual-sparger airlift bioreactor 1100 through the second manifold 1105 and distributed in the annular space via the sparger 1104. The sparger 1104 supplies the oxygen required for the cells to remain alive and grow. The riser is located in the inner tube 1102, and the downcomer is located in the annular space of the dual-sparger airlift bioreactor 1100.

[0097] In order to exploit the full benefits of the dual sparger design, close competition between the two spargers should be avoided. Under these conditions, liquid circulation is reduced and the bioreactor mixing behavior will deteriorate, and mass transfer efficiency will also be affected. Another extreme to avoid is too high a liquid velocity in the downcomer, which drives the gas bubbles in the downcomer downward and forces them to rise in the riser, thereby reducing oxygen transfer efficiency. This phenomenon is more likely to occur in airlift bioreactors with very tall airlifts.

[0098] Bioreactor spargers typically produce bubbles with a range of sizes. Bubbles of different sizes rise at different speeds, making fine-tuning control less obvious. By changing the cross-section of the central tube 1102 to become Fig. 12A The center tube 1202, Fig. 12B Central tube 1212 or Fig. 12C The central tube 1222 can slow down or capture a wider range of oxygen bubbles. Fig. 12C As seen in Figure 1, the annular and central space cross sections can be adjusted independently, e.g., the annular space remains constant while the central chamber has a gradual step change. The same concept of varying cross-sectional area can be applied to both the central distribution dominated scenario and the external circulation airlift bioreactor scenario.

[0099] In some embodiments, one or more additional feeds are added to the dual sparger airlift bioreactor 1100. A floating center tube extender 1302 can be added to the dual sparger airlift bioreactor 1100 to automatically accommodate increased liquid levels in the dual sparger airlift bioreactor 1100. This design is well suited for fed-batch cell culture, where the bioreactor working volume changes over the course of a batch. Fig.13A and Fig. 13B As seen in FIG. 1 , floating center tube extender 1302 rises as the level of liquid 1308 rises. No mechanical actuation mechanism is required. Floating device 1304 may be a hollow ring or other shape or form that provides a central balancing buoyancy.

[0100] The double sparger airlift design is also applied to external loop airlift bioreactors, where the riser and downcomer are two separate volumes connected in the top and bottom. Fig.14A Illustrated is a side view of a dual sparger airlift bioreactor according to some embodiments. Fig. 14BA top view of a dual sparger airlift bioreactor according to some embodiments is illustrated. In the example shown, the dual sparger airlift bioreactor 1400 includes a container 1401, which includes a liquid 1408. The container is coupled to an airlift tube 1402 outside the container 1401. The container 1401 includes a first sparger 1405 and an airlift tube 1402 including a second sparger 1406. The first sparger 1405 and the second sparger 1406 are coupled to a controller (not shown). The controller is configured to control the corresponding distribution rates associated with the first sparger 1405 and the second sparger 1406. In some embodiments, the distribution rate associated with the first sparger 1405 is significantly higher (e.g., greater than a threshold amount) than the second sparger 1406, so that the container 1401 is an ascending tube and the airlift tube 1402 is a descending tube. In some embodiments, the distribution rate associated with the second sparger 1406 is significantly higher (eg, greater than a threshold amount) than the first sparger 1405 such that the vessel 1401 is a downcomer and the airlift tube 1402 is a riser.

[0101] Fig.15 15 is a graph comparing an annularly distributed airlift bioreactor, a tubularly distributed airlift bioreactor, and a dually distributed airlift bioreactor. In the example shown, graph 1500 includes a first set of points 1502, a second set of points 1504, and a third set of points 1506. The first set of points 1502 corresponds to an annularly distributed airlift bioreactor, the second set of points 1504 corresponds to a tubularly distributed airlift bioreactor, and the third set of points 1506 corresponds to a dually distributed airlift bioreactor. Graph 1500 compares the mass transfer coefficient (kLa) and the fraction of airlift bioreactors that are tubularly distributed.

[0102] A plurality of points included in the first group 1502 are associated with corresponding gas flow rates. The graph 1500 indicates corresponding mass transfer coefficients for the gas flow rates included in the first group 1502. The plurality of points included in the first group 1502 may be associated with a dual sparger airlift with a fully annular distribution (e.g., no tubular distribution) or an airlift bioreactor with an annular distribution (e.g., the airlift bioreactor 1050).

[0103] A plurality of points included in the second group 1504 are associated with corresponding gas flow rates. The graph 1500 indicates corresponding mass transfer coefficients for the gas flow rates included in the second group 1504. The plurality of points included in the second group 1504 are associated with a dual sparger airlift with a fully tubular distribution (e.g., no annular distribution) or an airlift bioreactor with a tubular distribution (e.g., the airlift bioreactor 1000).

[0104] A plurality of points included in the third group 1506 are associated with corresponding gas flow rates. The graph 1500 indicates corresponding mass transfer coefficients for the gas flow rates included in the third group 1506. A plurality of points included in the third group 1506 are associated with airlift bioreactors that are both tubular and annular in distribution. For readability purposes, some points are included in the third group of points.

[0105] When the dual sparger airlift bioreactor is tubularly distributed and annularly distributed, the mass transfer coefficient associated with the gas flow rate increases. In some embodiments, the dual sparger airlift bioreactor is in annular distribution dominant mode (e.g., a tubular distribution fraction of 0-0.5). In some embodiments, the dual sparger airlift bioreactor is in tubular distribution dominant mode (e.g., a tubular distribution fraction of 0.5-1). As seen in chart 1500, when the dual sparger airlift bioreactor is tubularly distributed and annularly distributed, the mass transfer coefficient associated with the gas flow rate 1512 can be increased from the mass transfer coefficient associated with the gas flow rate 1512a (100% annular distribution) to the mass transfer coefficient associated with the gas flow rate 1512c, the mass transfer coefficient associated with the gas flow rate 1512d, or the mass transfer coefficient associated with the gas flow rate 1512e. When the dual-sparger airlift bioreactor is tubularly distributed and annularly distributed, the mass transfer coefficient associated with the gas flow rate 1512 can be increased from the mass transfer coefficient associated with the gas flow rate 1512b (100% tubular distribution) to the mass transfer coefficient associated with the gas flow rate 1512c, the mass transfer coefficient associated with the gas flow rate 1512d, or the mass transfer coefficient associated with the gas flow rate 1512e.

[0106] The improved airlift bioreactor described above can support the cultivation of cells in suspension, cell aggregates or cells on microcarriers. It can also be equipped with a cell retention device to enable perfusion of the cell culture.

[0107] An additional benefit of the dual sparger design is that the sparger can be used as a spray ball during the cleaning in place (CIP) step between two cell culture batches and clean the blind spots in the riser and downcomer walls in the top of the bioreactor that cannot be covered by a conventional spray ball. In some embodiments, detergent or other cleaning solution is introduced into the bioreactor via sparger 1105 to clean the annular space. In some embodiments, detergent or other cleaning solution is introduced into the bioreactor via sparger 1103 to clean the inner tube space.

[0108] In some embodiments, the tubular distributor may take the shape of a sphere, a straight line, a curve, a ring, or any practical shape. In some embodiments, the annular distributor may take the shape of a sphere, a straight line, a curve, a ring, or any practical shape.

[0109] Fig.161 is a block diagram illustrating a system for controlling a dual sparger airlift bioreactor according to some embodiments. In the example shown, the system 1600 includes a dual sparger airlift bioreactor 1601 coupled to a controller 1612. The dual sparger airlift bioreactor 1601 includes a first sparger 1603 and a second sparger 1604. The corresponding distribution rates associated with the sparger 1603, 1604 are controlled by the controller 1612. In some embodiments, the controller 1612 controls the distribution rate associated with the sparger 1603 to be higher than the distribution rate associated with the sparger 1604. In some embodiments, the controller 1612 controls the distribution rate associated with the sparger 1604 to be higher than the distribution rate associated with the sparger 1603. The controller 1612 can control the distribution rate associated with the sparger 1603 to be equal to the distribution rate associated with the sparger 1603, however, as discussed above, under those conditions, liquid circulation is weakened and the bioreactor mixing behavior will deteriorate, and mass transfer efficiency will also be affected. In some embodiments, the controller 1612 is configured to switch the riser and downcomer roles of the annular space and the inner tube space. In some embodiments, the controller 1612 controls the air / nitrogen / carbon dioxide mixture ratio and flow rate associated with the sparger 1603 to target the dissolved carbon dioxide set point, and controls the oxygen flow rate associated with the sparger 1604 to target the dissolved oxygen set point. In some embodiments, the controller 1612 controls the air / nitrogen / carbon dioxide mixture ratio and flow rate associated with the sparger 1604 to target the dissolved carbon dioxide set point, and controls the oxygen flow rate associated with the sparger 1603 to target the dissolved oxygen set point.

[0110] In some embodiments, each of the airlift tubes included in a cluster airlift bioreactor, such as cluster airlift bioreactor 150 , is dual distributed and controlled via controller 1612 .

[0111] Fig.17 1700 is a flow chart illustrating a process for utilizing a dual sparger airlift bioreactor according to some embodiments. In the example shown, process 1700 may be implemented by a controller (such as controller 1602) of a dual sparger airlift bioreactor (such as dual sparger airlift bioreactor 1100).

[0112] At 1702, a distribution rate associated with at least one of the spargers included in a dual-sparger airlift bioreactor is adjusted. The dual-sparger airlift bioreactor includes a tubular sparger included in an inner tube and an annular sparger included in an annulus. A distribution rate of the tubular sparger and / or the annular sparger is adjusted.

[0113] At 1704, the mass transfer coefficient is monitored over a specified period of time.

[0114] At 1706, it is determined whether the mass transfer coefficient matches the expected mass transfer coefficient. In response to determining that the mass transfer coefficient matches the expected mass transfer coefficient, process 1700 proceeds to 1708. In response to determining that the mass transfer coefficient does not match the expected mass transfer coefficient, process 1700 returns to 1702.

[0115] At 1708, a distribution rate associated with at least one of a plurality of spargers included in the dual-sparger airlift bioreactor is maintained until the cell culture batch is complete.

[0116] Although the foregoing embodiments have been described in some detail for purposes of clarity of understanding, the invention is not limited to the details provided. There are many alternative ways of implementing the invention. The disclosed embodiments are illustrative, not restrictive.

Claims

1. A bioreactor comprising: Multiple distributors; Multiple vertical circulation loops, where: A first vertical circulation loop of the plurality of vertical circulation loops comprises a first distribution area and a first return area, The first vertical circulation loop is in fluid communication with one or more other loops of the plurality of vertical circulation loops, and The first vertical circulation loop is characterized by an individual loop mass transfer coefficient; and A controller is coupled to the plurality of distributors and configured to control the plurality of distributors together so that a cumulative mass transfer coefficient of the plurality of vertical circulation loops is within a threshold value of the individual loop mass transfer coefficient associated with the first vertical circulation loop.

2. The bioreactor according to claim 1, wherein A first distributor of the plurality of distributors is included in the first distribution area.

3. The bioreactor according to claim 2, wherein: The first distributor is a ring-shaped distributor.

4. The bioreactor according to claim 2, wherein: The first distributor is a tubular distributor.

5. The bioreactor according to claim 1, wherein The plurality of distributors include a plurality of annular distributors and a plurality of tubular distributors.

6. The bioreactor according to claim 1, wherein The first distribution zone is inside the bioreactor and the first return zone is outside the bioreactor.

7. The bioreactor according to claim 1, wherein: The vertical circulation loop has a cylindrical shape, a rectangular shape, a triangular shape, a square shape, a pentagonal shape, a hexagonal shape, a heptagonal shape, an octagonal shape, a nonagonal shape and / or a decagonal shape.

8. The bioreactor according to claim 1, wherein The shape associated with the first vertical circulation loop is different than at least one or more other vertical circulation loops.

9. The bioreactor of claim 1 further comprising one or more sensors, the one or more sensors comprising at least one of a pH sensor, a temperature sensor, a dissolved oxygen sensor, a dissolved carbon dioxide sensor, a biocapacitive sensor, a Raman sensor, and / or a near infrared sensor.

10. The bioreactor according to claim 1, wherein: The controller is coupled to one or more sensors and is configured to control the plurality of distributors based on outputs of the one or more sensors.

11. The bioreactor according to claim 1, wherein: Additives are introduced into the liquid contained in the bioreactor.

12. The bioreactor according to claim 11, wherein The liquid is a cell culture medium associated with a plurality of cells included in the bioreactor.

13. The bioreactor according to claim 11, wherein: The additive is an inoculant, an acid or a base.

14. The bioreactor according to claim 11, wherein The controller individually controls one or more of the plurality of spargers to generate a horizontal liquid flow including the additive within the bioreactor.

15. The bioreactor according to claim 11, wherein The controller is configured to control a first distributor of the plurality of distributors to distribute the liquid at a first rate that is different from a distribution rate associated with one or more other distributors of the plurality of distributors.

16. The bioreactor according to claim 1, wherein: The controller is configured to control the plurality of distributors to switch between an annular distribution mode and a tubular distribution mode.

17. The bioreactor according to claim 1, wherein: The first distribution area is included in the airlift pipe.

18. The bioreactor of claim 1, further comprising a container comprising the plurality of spargers and the plurality of vertical circulation loops.

19. The bioreactor according to claim 18, wherein The bottom of the container is flat.

20. The bioreactor of claim 18, wherein: The bottom of the vessel has a corresponding concave retainer for the gas lift tube associated with each of the plurality of vertical circulation loops.

21. An airlift bioreactor comprising: ontology; First distribution area; Second distribution area; a first distributor configured to distribute a first gas within the first distribution area; a second distributor configured to distribute a second gas within a distribution area; and A controller is coupled to the first sparger and the second sparger and is configured to control a first flow rate associated with the first sparger and a second flow rate associated with the second sparger.

22. The airlift bioreactor of claim 21, wherein: The first gas is oxygen and the second gas is a combination of air, nitrogen and carbon dioxide.

23. The airlift bioreactor of claim 21, wherein: The first gas is a combination of air, nitrogen and carbon dioxide, and the second gas is oxygen.

24. The airlift bioreactor of claim 21, wherein: The first distribution area is in an inner tube within the body, and the second distribution area is an annular space between the body and the inner tube.

25. The airlift bioreactor of claim 24, wherein: The second flow rate associated with the second sparger is greater than the first flow rate associated with the first sparger.

26. The airlift bioreactor of claim 24, wherein: The mass transfer coefficient associated with the airlift bioreactor is based on the ratio of the cross-sectional areas between the inner tube and the annulus.

27. The airlift bioreactor of claim 24, wherein: The mass transfer coefficient associated with the airlift bioreactor is based on a diameter to height ratio associated with the inner tube.

28. The airlift bioreactor of claim 24, wherein: The inner tube is tapered.

29. The airlift bioreactor of claim 24, wherein: The inner tube includes a step change.

30. The airlift bioreactor of claim 29, wherein: The step change includes a boundary portion.

31. The airlift bioreactor of claim 21 further comprising an inner tube extender positioned within the body.

32. The airlift bioreactor of claim 31, wherein: The inner tube extender is configured to float in liquid stored in the body of the airlift bioreactor.

33. The airlift bioreactor of claim 21, wherein: The body is coupled to an external air lift, wherein the body is the second distribution area and the external air lift is the first distribution area.

34. The airlift bioreactor of claim 21, wherein: The liquid stored in the body of the airlift bioreactor is a cell culture medium associated with a plurality of cells included in the airlift bioreactor.

35. The airlift bioreactor of claim 21, wherein: The ratio of the height to the diameter of the airlift bioreactor is between 5-10.

36. The airlift bioreactor of claim 21, wherein: The controller is configured to control the first distributor and the second distributor for an annular distribution dominant mode.

37. The airlift bioreactor of claim 21, wherein: The controller is configured to control the first and second distributors for a tubular distribution dominant mode.

38. The airlift bioreactor of claim 21, further comprising one or more sensors.

39. The airlift bioreactor of claim 38, wherein: The one or more sensors include at least one of a pH sensor, a temperature sensor, a dissolved oxygen sensor, and / or a dissolved carbon dioxide sensor.

40. The airlift bioreactor of claim 38, wherein: The controller is coupled to the one or more sensors and is configured to control the first distributor and the second distributor based on outputs of the one or more sensors.

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