JPH0671422B2 - Raw material supply control method for tubular bioreactor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a raw material supply method for a tubular bioreactor in which a porous membrane and a reaction tank are integrated. In particular, it relates to a method for supplying a raw material to a highly efficient tubular bioreactor having a novel structure capable of continuously performing a reaction and a separation operation.

[Prior Art] Conventionally, it has been difficult to continuously carry out a reaction using a biocatalyst such as a microorganism or an enzyme, and it has hardly been industrially carried out. This is because it is difficult to control the microbial concentration when the biocatalyst is a microorganism, and it is difficult to recover and reuse an expensive enzyme when the biocatalyst is an enzyme.

Further, there is a research example of a loop type reactor mainly intended for application to a suspension polymerization reaction, but this is a batch reaction device and is an open system, so a separation operation is not performed during the reaction. Therefore, there is no relevant prior art in the tubular bioreactor, which is a closed loop continuous reaction apparatus that simultaneously performs reaction and separation.

As an example of a conventional membrane bioreactor, a membrane bioreactor of a type in which a fermenter and a membrane separator are connected as shown in FIGS. 3 and 4 will be described.
Common members are designated by the same reference numerals in FIGS. 3 and 4. The fermentation liquid is introduced from the fermentation tank 1 to the membrane module 4 by the circulation pump 2 and filtered, and the retentate is returned to the fermentation tank 1 again. The membrane permeate is discharged from the permeate pipe 10. The inlet pressure and the outlet pressure of the membrane 4 are measured by the pressure gauge 3 and the pressure gauge 5, respectively, and the filtration operation conditions are set by adjusting the discharge amount of the circulation pump 2 and operating the pressure adjustment valve 6. The raw material supply control method in this case is as follows. In the case of FIG. 3, the computer is based on the measured value of the permeated liquid by the flow rate measuring means 11.
The flow rate control valve 12 is operated by 13 to control the permeate flow rate so as to reach the set value. On the other hand, the level sensor 7 attached to the fermenter 1 detects the liquid level, and the raw material supply pump is intermittently operated according to the instruction of the level controller 8 to maintain the liquid amount in the fermenter constant. In the case of FIG. 4, the raw material supply pump 9 is maintained at a constant flow rate, and the permeate valve 14 is opened / closed according to the instruction of the level controller 8 to maintain the constant liquid amount in the fermenter.

[Problems to be Solved by the Invention] The present invention provides an improved method for controlling the raw material supply of a tubular bioreactor disclosed in Japanese Patent Application No. 62-146245. That is, a closed loop is formed by a tubular path, a porous tubular membrane is inserted in the tubular path, the raw material and the biocatalyst are supplied as a mixed liquid in the closed loop, and the reaction is circulated in the loop to form a tubular membrane. The present invention provides an improved control method for feed of a tubular bioreactor adapted to remove permeated product. It is an object of the present invention to provide a raw material supply control method in a closed tubular bioreactor, which prevents abnormal high pressure or low pressure in the reactor and prevents cavitation of the pump. Therefore, it is an object of the present invention to provide a raw material supply method for a tubular bioreactor, which can always balance the outflow amount of the reaction product, that is, the membrane permeate amount, and the raw material supply amount.

[Means for Solving Problems] In order to control the supply of the raw material for the purpose as described above, the gist of the present invention is to form a closed loop in a tubular passage, and to form a porous tubular membrane in the tubular passage. A product take-out port that is inserted and takes out the product that has permeated the tubular membrane, and a raw material supply port, and a circulation device that circulates a mixed liquid containing the raw material, the biocatalyst, and the product in the closed loop. In a bioreactor for producing a useful substance by a biocatalytic reaction in a fluid by a fluidized biocatalyst, (A) a raw material supply port is provided on the suction side of the circulation device of a reactor main circulation pipe for automatically sucking the raw material, (B) A raw material supply control method for a tubular bioreactor in which a flow rate control valve for arbitrarily adjusting a flow rate is attached to a membrane permeate side pipe to control a membrane permeation flow rate, and further, (C) a membrane A flow rate measuring device is provided in the permeate side pipe, and (D) the raw material supply amount is set based on the effective volume of the tubular bioreactor so that the predetermined dilution rate is obtained, and the membrane permeation flow rate is set to the set amount. It is a method of controlling the raw material supply of the tubular bioreactor by controlling. Further, it is preferable to control the feed of the raw material of the tubular bioreactor by increasing the pressure in the tubular bioreactor and providing a pressurized gas or a pump for pressurizing the raw material supply passage so as to increase the membrane permeation rate. is there.

Generally, in the biocatalytic reaction, the reaction rate depends on the substrate concentration when the concentration of the substance serving as the substrate in the medium is below the saturation value, and when it is above the saturation value, it takes a constant value regardless of the substrate concentration. . Therefore, in the continuous reaction system, the reaction rate becomes small when the substrate supply rate is small, and the surplus substrate flows out when it is larger than necessary. Therefore, in a continuous reactor such as a tubular bioreactor,
In order to keep the reaction efficiency at the maximum, it is necessary to set the raw material supply rate to an optimum value in order to keep the utilization efficiency of the raw material at the maximum. However, the tubular bioreactor is a reaction device that separates the biocatalyst and the reaction product at the same time as the reaction by using the porous membrane, so the outflow amount of the reaction product is controlled by the permeation rate of the membrane. . Therefore, in order to set the raw material supply rate to an appropriate value, it is necessary to control the permeation rate by some method.

Since the tubular bioreactor is a closed system,
The flow rate of the reaction product, that is, if the feed rate of the raw material is large compared to the flow rate of the permeate, the inside of the reactor will be in an abnormally high pressure state, and conversely if it is small, it will cause cavitation of the pump due to an abnormally low pressure. It is necessary to always balance the amount of permeate with the amount of raw material supplied.

[Example] Hereinafter, the configuration of the raw material supply control of the tubular bioreactor of the present invention will be described with reference to FIG.

The tubular bioreactor is composed of a circulation pump 1, membrane modules 2 to 5, a heat exchanger 6 and a pipe connecting them.

And, in the tubular bioreactor of the present invention,
As shown in FIG. 1, pressure sensors 7 and 8, turbidity sensor 9, temperature sensor 10, pH sensor 11, and pH controller 1 are further provided.
2, chemical pump 13, chemical injection port 14, raw material supply port 15, raw material tank 16, internal pressure adjusting port 17, disinfection filter 18, pressure control valve 19, disinfection filter 20, pressurizing pump 21, flow rate measuring means 22, The flow control valve 23, the computer 24, the compressor 25, and the gas cylinder 26 are provided.

The membrane modules 2 to 5 incorporate as many internal pressure tubular ceramic membranes as necessary. The reaction liquid is circulated through the closed loop tubular passage by the circulation pump 1 and cross-flow filtered by the membrane modules 2 to 5 to separate the reaction product and the biocatalyst.

The circulation pump 1 secures pressurization and membrane flow velocity for circulation of the reaction solution and cross-flow filtration. The pressure sensor 7 measures the inlet pressure of the membrane module 2 and the pressure sensor 8 measures the outlet pressure of the membrane module 5,
Monitor operating conditions. The temperature inside the reactor is controlled by adjusting the flow rate of constant temperature water to the heat exchanger based on the measured value of the temperature sensor 10. Since the temperature inside the reactor rises due to the heat generated by the circulation pump 1 and the heat of biocatalytic reaction, the temperature sensor 10 is exchanged between the circulation pump 1 and the membrane module 2 on the side of the circulation pump 1, and the heat exchange is performed on the side of the membrane module 2. A vessel 6 is provided.

In addition, the closed loop of the tubular bioreactor may be covered with a heat insulating material so as not to be affected by the outside air temperature.
Based on the measured value of pH sensor 11, pH controller 12
The alkaline or acid solution is injected and controlled by the chemical pump 13. The solution injection port 14 is provided between the membrane module 5 and the circulation pump 1, which has the lowest pressure in the reactor, in order to reduce the feed liquid load of the chemical liquid pump 13. In addition, the injected alkali or acid solution may have some delay until it is completely mixed.
11 is provided on the flow direction side of the solution injection port 14.

The biocatalyst concentration measurement values measured by the temperature, pressure, pH, and turbidity sensor 9 are monitored and recorded by the computer 24.

The raw material has the lowest pressure in the loop, and the raw material supply port 15 installed at a position as close as possible to the circulation pump between the membrane module 5 and the circulation pump 1 where the suction action is high,
An amount equal to the amount of the permeated liquid is naturally sucked. The raw material tank 16 is of a closed type so that various bacteria do not enter, and the internal pressure adjusting port 17 is provided with a sterilizing filter 18 and a pressure adjusting valve 19. A sterilized raw material is aseptically supplied to the raw material tank 16.

By supplying the raw materials under pressure within the allowable range of the reactor, the pressure inside the reactor can be increased and the filtration rate can be increased. Therefore, the compressor is installed in the raw material tank 16.
25 or a gas cylinder 26 or the like to supply a pressurized gas through the sterilization filter 20, or by providing a pressurizing pump 21 in the pipe between the raw material tank 16 and the raw material supply port 15, The pressure required for pressure can be obtained. However, since the tubular bioreactor controls the permeate flow rate to a constant value, the pressurizing pump uses a centrifugal pump that can be closed and closed because the raw material supply amount becomes insufficient in the positive displacement pump. To do.

The membrane permeate flow rate is measured online by using the flow rate measuring means 22 such as a flow meter or a load cell,
Based on the measurement result, the flow control valve 23 is feedback-controlled by the computer 24 to adjust it to the set value. The permeated liquid flow rate, the permeated liquid integrated amount, and the flow control valve control voltage are monitored and recorded by the computer 24.

[Operation] Since the tubular bioreactor is a closed system,
If the feed rate of the raw material is large compared to the permeate flow rate, the inside of the tubular bioreactor will be in an abnormally high pressure state, and conversely if it is small, it will cause cavitation of the pump due to an abnormally low pressure. Therefore, it is necessary to balance the permeate flow rate and the raw material supply rate by some means, and to set the dilution rate, which is an operation variable, to an arbitrary value. Here, the dilution rate is a value obtained by dividing the raw material supply rate by the reactor effective volume, and is the reciprocal of the residence time. The effective volume of the reactor, in the case of a tubular bioreactor, corresponds to the total volume of liquid that fills the closed loop tubular path of the tubular bioreactor. In order to keep the reaction efficiency at the maximum and to keep the reaction product concentration constant,
It is necessary to set the dilution rate to an optimum value based on the reaction state at that time.

First, a method was considered in which the permeated liquid flow rate and the raw material supply path were independently controlled to make them coincident with each other. The structure is shown in FIG.

The permeated liquid flow rate is set to a set value by measuring the permeated liquid flow rate online using the flow rate measuring means 1 such as a flow meter or a load cell, and based on the measurement result, the computer 5 feedback-controls the flow rate control valve 2. It is to be adjusted.

The raw material supply rate is set to the same as the permeate flow rate by performing online measurement of the permeate flow rate using the flow rate measuring means 3 and based on the measurement result, the computer 5 feedback-controls the discharge rate of the raw material supply pump 4. It is controlled so that it becomes a value. The raw material supply port 6 may be provided at any part of the tubular bioreactor, but the raw material supply pump 4 needs to have a discharge pressure higher than the operating pressure of the tubular bioreactor.

However, in this method, it is very difficult to exactly match the permeate flow rate and the raw material supply rate, and an error may occur between the two during long-time operation. Since the tubular bioreactor is a closed system, the method of the present invention utilizes the fact that when the internal liquid flows out due to membrane permeation, the pressure decreases in the vicinity of the pump / suction portion and acts to restore the original pressure state. However, since the same amount of raw material as the membrane permeate is automatically supplied, it is possible to set the target raw material supply rate, that is, the dilution rate, by controlling only the permeate flow rate.

In FIG. 1, the permeated liquid flow rate is set to a set amount by feedback controlling the liquid amount adjusting valve 23 by the computer 24 based on the permeated liquid flow rate measured value by the flow rate measuring means 22 such as a flow meter or a load cell. To adjust.

The present invention will be further described below by an experimental example of controlling the feed rate of raw materials in a high-density continuous culture of lactic acid bacteria using a tubular bioreactor. The tubular bioreactor used in the experiment has the structure shown in FIG.

The circulation pump 1 is a positive displacement rotary pump, and has both pressurization and circulation. Therefore, the pressurizing pump 21, the compressor 25, the gas cylinder 26, the internal pressure adjusting valve 17, the sterilization filter 18, and the respective devices required for pressurizing the system of the pressure adjusting valve 19 are not provided. A load cell was used as the permeated liquid flow rate measuring means 22. Also, in order to measure the raw material supply,
The raw material tank was also equipped with a load cell 27. Others are first
It is the same as the one shown in the figure. The volume of the tubular bioreactor device was 2.6.

[Experimental Example 1] When the raw material supply rate is constant: Dilution rate is 0.32 (1 / h), that is, the set value Fp of the permeate flow rate is set by the flow rate measuring means 22 of the load cell as described in [Operation] above. Based on the measured permeated liquid flow rate value, the computer 24 sets the flow rate control valve 23 to Fp = 0.835 (/
h) was controlled. The raw material is sucked into the tubular bioreactor from the raw material supply port 15 at a rate equal to Fp = 0.832 (/ h), and it was confirmed by the load cell 27 provided in the raw material tank that the suction rate was equal to Fp. .

[Experimental Example 2] When the raw material supply rate is proportional to the bacterial cell concentration: In the method of culturing, the raw material is supplied in proportion to the lactic acid bacterium concentration.
An example of culturing lactic acid bacteria is shown below.

The material supply rate, that is, the permeate flow rate Fp = a · X is set.
Here, a is a proportional constant and X is a lactic acid bacterium concentration. In the experiment, a = 0.0832. The lactic acid bacterium concentration X was measured by the turbidimeter 9, and the flow rate control valve 23 was controlled by the computer 24 based on the permeate flow rate value calculated from this measurement value.

When the culture is started by making the feed rate proportional to the concentration of lactic acid bacteria, and the bacterial cell concentration is X ₀ , the time elapsed from the start of such culture is t, and the specific growth rate of the bacterial cells is Is X, X = X ₀ exp (−μt). Therefore, Fp is Fp = 0.0832exp (−μt).

According to this formula, since the bacterial cell concentration exponentially increases, the permeate flow rate exponentially increases, but as in Experimental Example 1, the permeate flow rate by the load cell 22 and the raw material supply amount by the load cell 27 match. It was confirmed to do.

EFFECT OF THE INVENTION By the method for controlling the feed of raw materials to the tubular bioreactor according to the present invention, firstly, the membrane permeate flow rate and the feed amount of raw materials are balanced,
Also, to provide a raw material supply method capable of setting the dilution ratio in the reaction solution to an arbitrary level. Second, to a tubular bioreactor capable of maintaining the reaction efficiency at the maximum and the reaction product concentration at a constant level. Thirdly, since the same amount of raw material as the membrane permeate is automatically supplied, if only the permeate is controlled, the desired raw material feed rate, that is, the optimum dilution is obtained. It was possible to provide a raw material supply control method that can set the rate, and other remarkable technical effects were obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram schematically illustrating a configuration for controlling the raw material supply of the tubular bioreactor of the present invention. FIG. 2 is a schematic diagram for explaining a method of supplying a raw material to a tubular bioreactor conventionally considered by the present inventor. FIG. 3 is a schematic diagram illustrating a conventional continuous biological reaction device. FIG. 4 is a schematic diagram illustrating a conventional continuous biological reaction device. [Description of symbols of main parts] 1 ... Circulation pumps 2-5 ... Membrane module 6 ... Heat exchanger 7, 8 ... Pressure sensor 9, 10 ... Temperature sensor 11 ... pH sensor 12 ... pH Controller 15 …… Raw material supply port 16 …… Raw material tank 17, 19 …… Pressure control valve 20 …… Sterilization filter 21 …… Pressurizing pump 22 …… Flow rate measuring means 23 …… Flow rate control valve 24 …… Computer 27… … Load cell

Front page continuation (72) Inventor Teruyuki Nagato, 2-1, Hirosawa, Wako-shi, Saitama RIKEN (72) Inventor Susumu Tatekawa 63-30 Yuhigaoka, Hiratsuka-shi, Kanagawa Sumitomo Heavy Industries Machinery Co., Ltd. In-house (56) Reference JP-A-63-313576 (JP, A) JP-A-63-188384 (JP, A) JP-A-49-50989 (JP, A)

Claims (3)

[Claims] 1. A closed loop is formed by a tubular passage, a porous tubular membrane is inserted in the tubular passage, and a product take-out port for taking out a product permeating the tubular membrane and a raw material supply port are provided. In a bioreactor for producing a useful substance by a biocatalytic reaction in a fluid by a fluidized biocatalyst, a circulation device for circulating a mixed liquid containing a raw material, a biocatalyst, and a product in a closed loop is provided. Is installed on the suction side of the circulation device of the reactor main circulation pipe that automatically sucks the raw material, and (B) a flow rate control valve for arbitrarily adjusting the flow rate is attached to the membrane permeate side pipe to control the membrane permeation flow rate. A method for controlling the supply of raw materials in a tubular bioreactor, characterized by: 2. Further, (C) a flow rate measuring device is provided in the membrane permeate side pipe, and (D) the raw material supply amount is set based on the effective volume of the tubular bioreactor so as to obtain a predetermined dilution rate, and the setting is made. The raw material supply control method for a tubular bioreactor according to claim 1, characterized in that the membrane permeation flow rate is controlled so that the amount becomes the same. 3. The pressure in the tubular bioreactor is increased by supplying a pressurized gas to the raw material supply passage or by a pressurizing pump to increase the membrane permeation rate. Feeding control method for tubular bioreactor.