JPH04190782A - Bioreactor - Google Patents

Abstract

PURPOSE:To obtain a bioreactor capable of converting CO2 into O2 by photosynthesis by passing fine algae and culture medium into a vessel in which a gas- exchangeable hollow fiber membrane and optical fiber having high light permeable property are integrated, feeding CO2 from the side wall and irradiating the optical fiber with light from light source. CONSTITUTION:In a bioreactor capable of converting CO2 into O2 utilizing photosynthesis of fine algae, the fine algae and culture medium are passed through a vessel in which a number of hollow yarn membranes 6 having high light permeability and gas-exchangeable and a number of optical fibers 7 closely arranged to the vicinity thereof are integrated and CO2 riched gas inlet 3 communication a gas chamber of a vessel is provided behind the flow direction of side wall of the vessel and O2 riched gas inlet 4 communicating with the gas chamber is provided on the upper stream of flow direction of side wall of the vessel and a feed port 1 for feeding fine algae and culture liquid into a hollow yarn membrane 6 is provided on one end of the vessel and outlet 2 is provided on other end of vessel and the fine algae is irradiated with light from light source 8. Thereby CO2 is converted to O2 utilizing photosynthesis.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a bioreactor, and particularly to a bioreactor that converts CO2 into O2 using photosynthesis of microalgae.

[Conventional technology]

It is thought that bioreactors that utilize the photosynthetic function of microalgae will be applied to the following 20,000 areas in the future.

(1) As a life support system in space, a device that performs gas exchange to convert CD2 emitted by humans and other animals into 02, and also produces food and feed (closed life support system) (2) Thermal power plant A device that fixes CO2 emitted from

FIG. 5 shows a schematic diagram of a conventional bioreactor that utilizes the photosynthetic function of microalgae.

That is, the conventional bioreactor essentially consists of two elements: an algae culture tank 20 and a gas exchanger 19, and the algae culture tank 20 uses light energy as the driving force [1] below.
In this reaction, 02 and algae (main components are carbon, nitrogen, oxygen, phosphorus, and hydrogen) are obtained from CO2, H2O, and fertilizer (main components are P and N).

CD □ 10H, O + Fertilizer 10 Light Energy → 02 + Algae (1) The gas exchanger 19 is a pressurized module made of a hydrophobic porous membrane called an oxygenator formed into a hollow fiber shape. Utilizing the difference in concentration of carbon dioxide and oxygen inside and outside the hollow fiber, it has the function of supplying the carbon dioxide necessary for equation (1) and exhausting the oxygen generated in equation (1). 1) The light energy required for the formula is supplied from the light source 8 through the surface of the culture tank body 21 made of glass, acrylic, etc., and the fertilizer (liquid) is supplied from the fertilizer tank 16 to the fertilizer injection line by the fertilizer injection pump 14. 15 to the culture tank main body 21.

Further, at the same time as the fertilizer is sent, the algae produced by the formula (1) are collected through the algae collection line 17 together with the liquid containing the fertilizer in the culture tank body 21.

The inside of the culture tank 20 is sufficiently stirred by the stirrer 18. Since microalgae are small particles with a diameter of about 10 μm, they are completely suspended in the culture solution.

The culture solution inside the culture tank 20 is sent to the gas exchanger 19 via the culture solution inlet 1 by the circulation pump 11 while containing algae. The inner diameter of the hollow membrane 6 in the gas exchanger 19 is several hundred
It is large enough to allow microalgae to pass through, so the microalgae can pass through without being blocked.

On the other hand, CO2-enriched gas is also supplied from the CO2 generation source 24 by the gas circulation pump 23 to the gas exchanger 19 via the gas inlet 3.
sent to. In the gas exchanger 19, the gas and liquid pass through the hollow fiber membrane 6.
through indirect contact.

The culture solution sent to the gas exchanger 19 has a low C'0.2a degree and a high 02a degree due to the reaction of equation (1), so the C02 changes from gas to liquid due to the gas concentration difference between the liquid and gas. , 02 move from liquid to gas.

Therefore, from the gas outlet 4 comes a gas enriched with 02 with a low concentration of CO and S, while from the culture solution outlet 2 a culture solution containing algae with a low concentration of 0 and enriched with CO2 comes out. . The culture solution is recycled to the main body of the culture tank 20, and the 02 enriched gas is supplied to the 02 consumption section 25.

The rate of photosynthesis in a bioreactor depends on the light intensity ■. When is constant, it depends on the optical path length (the distance that light reaches the algae) and the algae concentration, and it is obvious that the operation should be made with the optical path length as small as possible and the algae concentration high. .

02 incidence per unit algal body Kp: 1.28X105 [
:mol-L/(kg-cells-h)), light intensity I.

: 20,000 [1ux], extinction coefficient E: 13
When 0 [1/m ・(kg-cells/m3) ],
An example of calculation of the 02 incidence Cd 02/1-tank h] against the algae concentration [kg-cells/m3] when the radius 1 [m] of the cylindrical bioreactor is changed is shown in Figure 6. It becomes like this.

[Problem to be solved by the invention]

As shown above, the photosynthesis rate in a bioreactor depends on the light intensity■. In a certain case, efficiency (photosynthesis rate per unit bioreactor volume) will improve if the light path length is made as small as possible and the algae concentration is increased. .

Therefore, in current bioreactors, there is a problem in that increasing the efficiency of photosynthesis reduces the volume and therefore the total rate of photosynthesis. That is, there is a problem that efficiency and total amount are contradictory and cannot be satisfied at the same time.

Therefore, in the current design of bioreactors, the optical path length and algae concentration are determined by considering the efficiency and total amount of photosynthesis suitable for the purpose of use.

At present, the optical path length is limited to the order of several centimeters, so cultivation is only possible at a thin algae concentration of about 1 [kg-cells/m']. Therefore, the efficiency of collecting algal bodies is poor.

In view of the above-mentioned state of the art, the present invention aims to provide a bioreactor with high photosynthetic efficiency and almost no decrease in the total amount of photosynthesis.

[Means to solve the problem]

The present invention relates to a container in which microalgae and a culture solution are distributed, and which integrates a large number of hollow membranes with high optical transparency and gas exchangeability into a module, and a large number of optical fibers arranged in close proximity to the hollow fiber membranes. an enriched gas inlet located upstream of the side wall of the container in the flow direction and communicating with the air chamber of the container;゜Enriched gas outlet, supply port provided at one end of the container to supply microalgae and culture solution into the hollow fiber membrane, provided at the other end of the container to discharge grown microalgae and culture solution The bioreactor is characterized in that the bioreactor is equipped with a discharge port for replenishing the optical fiber, a light source for irradiating the optical fiber, and a means for replenishing the supply port with a culture solution.

[Effect]

The bioreactor of the present invention can be said to be a bioreactor in which each hollow fiber membrane has a diameter of 1/10 m.
Since the optical path length can be on the order of m, the actual optical path length can be reduced from the conventional order of several cIII to the order of 1/10 mm. Therefore, the following can be said from FIG.

(1) Photosynthetic efficiency can be several tens of times higher than before (2) Algae concentration can be increased from the conventional 1 [kg-cells/m3] to over 15 [kg-cells/m3:] Moreover, as shown in FIG. 2, many hollow membranes are used facing toward the east, and each membrane can be said to be a highly efficient bioreactor, so it is expected that the total amount of photosynthesis will be large.

〔Example〕

The apparatus configuration of one embodiment of the present invention is shown in FIG.
This will be explained with reference to FIG. 2, which is a sectional view, and how to assemble the main parts of the device will be explained with reference to FIG. 3.

First, the main parts of the apparatus of the present invention will be explained with reference to FIG.

Cylindrical container (plastic such as polycarbonate) 26
A combination of an appropriate number of optical fibers 7 and hollow fiber membranes 6 is placed in the cylindrical container 26, and the openings at both ends of the cylindrical container 26 are hardened with an adhesive 27 such as epoxy resin.

Next, the culture solution inlet 1 and the liquid chamber 5 are placed at both ends of the cylindrical container 26.
The main part of the apparatus of the present invention is completed by attaching the cap 28 consisting of the culture medium outlet 2 and the liquid chamber 5 with an adhesive.

Next, the general operation of the present invention will be explained with reference to FIGS. 1 and 2.

An algal culture solution containing fertilizer and alga bodies necessary for the growth of algae enters a liquid chamber 5 from a culture solution inlet 1, where the liquid is dispersed and enters each hollow fiber membrane 6.

The following occurs within the hollow fiber membrane 6. The algae receive supply of CO7 and light energy from outside the hollow fiber membrane 6, perform photosynthesis, generate oxygen, and increase the number of algae bodies. The generated oxygen exits the hollow fiber membrane 6 (.

While the above reaction is carried out within the hollow membrane 6, the algae culture solution flows through the liquid chamber 5 toward the liquid outlet 2.

On the other hand, on the gas side, gas rich in CO□ enters from the gas inlet 3, passes between the hollow fiber membrane 6 in the air chamber 9 and the optical fiber 7, and exits from the gas outlet 4.

During this time, the following gas movement occurs due to the difference in gas concentration. CO2 is absorbed from the outside of the hollow fiber membrane 6 toward the algae culture solution inside. On the other hand, oxygen generated by the photosynthetic reaction within the hollow fiber membrane 6 is discharged from the inside of the hollow fiber membrane 6 toward the air chamber 9 outside.

Light is supplied from the light source 8 to the algae by guiding the light to the outside of the hollow membrane 6 using an optical fiber 7.

The optical fiber 7 and the hollow fiber membrane 6 are placed next to each other as shown in FIG.

FIG. 4 shows a schematic diagram of a CL treatment system using a bioreactor according to the present invention.

This system consists of a bioreactor 10, a line for supplying fertilizer, and a line for collecting algae.

The CO3-rich gas coming from CO□ source 24 is
Through the action of the gas circulation pump 23, the gas enters from the gas inlet 3, passes through the air chamber 9, and exits from the gas outlet 4. After being absorbed inside the hollow fiber membrane 6, it is converted into 02 by photosynthesis of algae. 02 generated by photosynthesis seeps out from inside the hollow fiber membrane 6 to the air chamber 9 side, and is then released from the gas outlet 4 to the 02 consumption section 2.
Sent to 5.

The algae enter through the liquid inlet 1 and exit through the liquid outlet 2, performing photosynthesis, processing CO2, and also propagating the algae themselves.

Therefore, the concentration of algae at the liquid outlet 2 is higher than the concentration of algae at the liquid inlet 1. The grown algae are collected through the algae collection line 17, but since algae seeds are needed at the liquid inlet 1, a part of the algae is sent from the branch point 12 through the algae recycling line 22 to the bioreactor 10. and recycled by the action of a circulation pump.

Further, the fertilizer consumed by photosynthesis is supplied from the algae fertilizer tank 16 to the junction with the algae recycling line 22 through the fertilizer injection line 15 by the action of the fertilizer injection pump 14.

[Effect of Hathu]

The present invention has the following advantages over conventional devices.

(1) Photosynthetic efficiency can be several tens of times higher than that of conventional hollow fibers Since the diameter of the hollow fiber is on the order of 1/10 mm, it is possible to reduce the optical path length from the conventional order of several Cl11 to the order of 1/10 mm. Therefore, it can be seen from FIG. 6 that the photosynthetic efficiency is several ten times that of the conventional method.

(2) There is almost no decrease in the total amount of photosynthesis.

Since the hollow fiber hollow fiber diameter is on the order of 1/10 mm,
Although the total amount of algae culture fluid flowing through the hollow fibers will be considerably smaller, considering that it is possible to increase the number of hollow fibers to several thousand, and that the efficiency can be several ten times higher than conventional methods. , there is almost no decrease in the total amount of photosynthesis.

(3) From the above, it is possible to simultaneously improve both the photosynthetic efficiency (photosynthetic rate per unit bioreactor volume) and the total amount of photosynthesis, which was impossible with conventional bioreactors.

(4) Since the operation can be performed at a concentration of algae that is 10 times higher than the current concentration, the efficiency when collecting algae is good.

(5) It is compact because the gas exchange device and the culture tank body, which were conventionally two parts, are integrated.

(6) Since the flow is laminar in the back type reactor, stirring is not necessary.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of the main parts of the bioreactor of the present invention, Figure 2
The figure is a sectional view taken along the line A-A in Figure 1, Figure 3 is an explanatory diagram of the assembly of the main parts of the bioreactor of the present invention, Figure 4 is an explanatory diagram of the action of the bioreactor of the present invention, and Figure 5 is a conventional bioreactor. Fig. 6 is a diagram illustrating an example of calculation of the incidence of 02 outbreaks with respect to the algae concentration when the radius of the cylindrical bioreactor is changed.

Claims (1)

[Claims] A container in which microalgae and a culture solution are distributed, a large number of hollow fiber membranes with high optical transparency and gas exchange capability, and a large number of optical fibers arranged in close proximity to the hollow fiber membranes are integrated into a module, and a side wall of the container. a CO_2-enriched gas inlet downstream of the container in the flow direction and communicating with the air chamber of the container;
_2 Enriched gas outlet, provided at one end of the container and supplying the microalgae and culture solution into the hollow fiber membrane, provided at the other end of the container and discharging the grown microalgae and culture solution. A bioreactor comprising: a discharge port for supplying a culture medium to the optical fiber; a light source for irradiating the optical fiber; and a means for replenishing the supply port with a culture solution.