RU2596396C1 - Bioreactor with membrane device for gas supply of microorganisms - Google Patents

Abstract

FIELD: biochemistry.

SUBSTANCE: invention relates to biochemistry. Proposed is a bioreactor with a membrane device for gas supply of microorganisms. Bioreactor comprises a cylindrical housing, a cover, a bottom, a heat exchanger, a gas distributor, an aerator, a methane collector, tubular gas-permeable polymer membranes, branch pipes for the working liquid and gas flowing, an analyzer of exhaust gases CH₄, O₂, CO₂, sensors of pH and T°C, electronic air flow and carbon dioxide meters, methane pressure regulator and enzymatic process controller. Gas distributor is equipped with guide plates and an aerating air diffuser, herewith it is made as a multichannel gas-lift pump. Methane collector is equipped with perforated holes for passage of liquid-gas mixture through the gas distributor. Separator of exhaust gases from liquid products of fermentation is equipped with working fluid level sensor and a pipeline connecting the lower part of the separator with the bottom part of the bioreactor.

EFFECT: higher efficiency and explosion safety of bioreactor are provided.

3 cl, 1 dwg

Description

The invention relates to the field of microbiology, in particular to bioreactors for growing biomass of microorganisms in an aqueous-mineral medium saturated with gaseous hydrocarbons, and can be used for the cultivation of aerobic or anaerobic microorganisms, as well as in research practice.

The process of growing microorganisms in natural gas (source of information: http://www.zges.ru/bio.php?wr=300) consists in the fact that the main nutrients are methane and oxygen, which must be dissolved in an aqueous-mineral medium in optimal ratio.

It was experimentally established that the need for bacteria in oxygen is 2-3 times higher than their need for methane. However, such a stoichiometric methane: oxygen ratio lies in the range of explosive concentrations, and taking into account this factor, the cultivation process is carried out with the composition of the gas phase that differs from the optimal one in the direction of excess methane with the corresponding oxygen limit. At the same time, it was noted that the presence of carbon dioxide in a gaseous mixture in concentrations from 3 to 10% (by volume) improves the growth of bacteria, and an oxygen content above 18% (by volume) causes cell death. Methane-oxidizing bacteria grow at pH 6.5-7.1 and temperatures 34-38 ° C. To ensure efficient cell growth, fermenters are usually used with intensive heat and mass transfer, which is provided by increasing the gas flow rate, improving mixing and increasing the working pressure in the bioreactor to increase the solubility of gases.

The well-known "Method for the production of biomass of aerobic microorganisms" (patent RU 2322488 C2).

The method involves the cultivation of microorganisms in a continuous circulation of the working fluid in a closed loop and with continuous saturation of the fluid with gaseous hydrocarbons and aerating agents, as well as in the flow of a water-mineral solution and removal of fermentation products.

Saturation of the working fluid with gaseous hydrocarbons and aerating agent is carried out separately, moreover, saturation with the aerating agent is carried out at its single contact with the working fluid, and saturation with gaseous hydrocarbons is carried out upon repeated contact with the working fluid by recirculation of gaseous hydrocarbons in a closed circuit until they are completely dissolved.

A significant disadvantage of this known method is the use of separate zones of dissolution of gaseous hydrocarbons and aerating agent, which leads to the formation of a gradient of dissolved gases, a violation of a given gas ratio and a decrease in the growth rate of microorganisms. Moreover, each device for dissolving gases contains zones of gas bubbles in which explosive concentrations of gases are formed during the exchange of the working fluid, which does not ensure the explosion-proof operation of the bioreactor.

The method is implemented in a bioreactor of complex design, which significantly increases its cost and complicates the control of hydrodynamic and fermentation processes.

The known method can be applied only in small volume bioreactors in which a high exchange rate of a working fluid saturated with different gases can be realized.

The closest analogue of the claimed invention is described in patent RU 2446205 C1 "Displacement bioreactor with a membrane gas supply device."

The known bioreactor comprises a cylindrical body, a cover, a bottom, a gas distribution device, gas-permeable tubular membranes mounted along the axis of the body. Inside the housing along its central axis, a support pipe of the heat exchanger is installed, in which a gas supply pipe is connected, connected to a gas distribution device. Outside of the supporting pipe of the heat exchanger, a screw perforated surface is installed, through the openings of which pass gas-permeable tubular membranes fixed between the cover and the gas distribution device.

The growth of microorganisms in a bioreactor is carried out under conditions of laminar displacement of liquid fermentation products by the initial nutrient medium through multiple channels formed by tubular gas-permeable membranes, inflated feed gases, which leads to the delamination of substances dissolved in the nutrient medium and to a decrease in productivity.

Gas membranes are inflated with a mixture of feed gases having different solubilities, which makes it difficult to create and maintain a predetermined ratio of dissolved gases in the working fluid, resulting in reduced bioreactor productivity.

The analog tubular heat exchanger is not very effective due to the small surface area of the heat exchanger pipe.

In fermentation processes, aeration gases and gases formed during the respiratory activity of microorganisms form a foam, which increases the volume of liquid fermentation products drained, reduces the working volume and productivity of the bioreactor.

The purpose of the invention

Improving the productivity and explosion safety of the bioreactor due to the intensification of mixing of the working fluid and the use of separate, namely diffusion input of methane and dispersion input of aerating agents into the water-mineral medium seeded with microorganisms.

The disadvantages of the aforementioned analogue are eliminated by the implementation of the above objective of the present invention using a bioreactor with a membrane gas supply device of microorganisms containing a cylindrical body, cover, bottom, heat exchanger, gas distribution device, methane collector, gas-permeable polymer membranes, nozzles for the flow of working liquids and gases, in which according to the present invention, the bioreactor further comprises an aerator for introducing atmospheric air into the working fluid in the form of fine codes ispersnoy fractions sensors pH, T ° C, and the liquid level, the electronic flow of air and carbon dioxide, methane pressure regulator separator waste gases from liquid fermentation products, flue gas analyzer CH _4, O _2, CO ₂ and fermentation controller process when this gas distribution device is made in the form of a multi-channel gas lift pump pumping a working fluid over multiple surfaces of polymer gas-permeable membranes; the methane collector is in communication with a methane pressure regulator; the aerator is connected through a bacterial filter and electronic flowmeters to sources of compressed atmospheric air and carbon dioxide; a separator of exhaust gases from liquid fermentation products is in communication with the upper cavity of the bioreactor through an adjustable exhaust gas damper; a gas analyzer is communicated with a separator of exhaust gases from liquid fermentation products through a bacterial filter.

In addition, this goal is achieved due to the fact that the bioreactor further comprises a pump for pumping the working fluid, located in the gap of the pipeline connecting the lower part of the separator tank with the bottom part of the bioreactor.

In addition, the body of the gas distribution device is equipped with a diffuser, in the cavity of which an aerator is placed and which directs the flow of aerating air into the gaps between the gas-permeable membranes, while the supporting part of the diffuser is equipped with cutouts for free flow of the working fluid.

In addition, the methane collector is provided with openings for the free flow of a gas-liquid mixture through a gas distribution device.

In addition, the separator of exhaust gases from liquid fermentation products is made in the form of a tank and carries a level sensor for the working fluid.

In addition, the gas distribution device is held in an upright position by means of guide plates and supported on the bottom of the bioreactor body, while the guide plates are fixed between the inner wall of the bioreactor body and the gas distribution device.

In addition, the heat exchanger is made in the form of a heat exchange jacket.

The bioreactor scheme according to the present invention is presented in the attached figure.

The bioreactor contains:

Cylindrical housing 1, cover 2, bottom 3, heat exchanger in the form of a heat exchange jacket 4, gas distribution device 5, polymer gas permeable membranes 6, methane collector 7, air aerator 8, guide plates 9, diffuser 10, gas separator 11, diaphragm pump 12 for transfer working fluid, a bacterial filter 13 of the inlet gases, a bacterial filter 14 of the exhaust gases, a damper 15 of the exhaust gas flow, a regulator 16 of methane pressure, an electronic flow meter 17 of air, an electronic flow meter 18 of carbon dioxide, a coupling of 19 sensors pH meter, temperature sensor sleeve 20, controlled valves 21-27, non-return valve 28, liquid level sensor sleeve 29, flue gas analyzer 30 CH ₄ , O ₂ , CO ₂ , nozzles 31-38, control controller 39.

Execution

- as the feed gas in the bioreactor according to the present invention uses natural gaseous methane;

- the methane collector is equipped with perforated holes for the through flow of the gas-liquid mixture through the gas distribution device;

- the gas distribution device is equipped with a diffuser, directing the flow of aerating air into the gaps between the gas-permeable membranes;

- as an aerator used, for example, a disk aerator company Matala, Australia;

- the supporting part of the diffuser is equipped with cutouts for the free flow of the working fluid;

- a separator of exhaust gases from liquid fermentation products is made in the form of a tank with a built-in level sensor for the working fluid;

- the gas distribution device is held in the bioreactor in an upright position by means of guide plates and with support on the bottom of the bioreactor body.

- the collector is connected by a pipeline with a methane pressure regulator;

- polymer membranes are placed in a gas distribution device with a gap of 5 mm between the walls of the membranes;

- the polymer membrane has a closed, for example, U-shape and is connected to a methane collector;

- the guide plates are fixed between the inner wall of the bioreactor and the body of the gas distribution device with the formation of a flow channel 10 mm wide;

- the aerator is placed in the cavity of the diffuser;

- the aerator through a bacterial filter and valves through pipelines communicated with electronic flow meters of air and carbon dioxide;

- a separator of exhaust gases from liquid fermentation products is communicated by a pipeline with the upper cavity of the bioreactor through an adjustable exhaust gas damper;

- the exhaust gas analyzer is connected by a pipeline with a separator of exhaust gases from liquid fermentation products through a bacterial filter;

- the diaphragm pump is located in the gap of the pipeline connecting the lower part of the separator tank with the bottom part of the bioreactor

- the heat exchanger is made in the form of a heat exchange jacket mounted on the bioreactor body;

- the controller is electrically connected (not shown in the figure) with sensors, valves and other actuators.

Bioreactor operation

Through the pipe 33 and the open valve 23 in the bioreactor contribute water-mineral medium to contact with the level sensor 29 in the gas separator 11. In the process of introducing the aqueous-mineral medium into the bioreactor, air from the bioreactor is vented to the atmosphere through the flow shutter 15, a separator 11, a bacterial filter 14, a gas analyzer 30, and a pipe 38.

Upon contact of the aqueous-mineral medium with the level sensor 29, the valve 23 is closed, the heat exchange jacket 4 is heated to a predetermined temperature of the fermentation process, and through the pipe 31 and the open valve 21, the aqueous-mineral medium is inoculated with a microorganism culture to form a working fluid.

The valve 21 is closed, and through the pipe 34, an electronic flow meter 17, an open valve 24, a bacterial filter 13, a non-return valve 28 and an aerator 8 with a given flow rate supply atmospheric air, which is displaced from the disk aerator 8 into the working fluid in the form of a fine fraction, saturating the working liquid oxygen and carbon dioxide air.

Methane with a predetermined pressure is introduced into the collector 7 through the pipe 32, the pressure regulator 16 and the open valve 22. Methane diffuses into the working fluid through the multiple surfaces of the gas-permeable polymer membranes 6, completely dissolving in the working fluid saturated with aerating air.

The undissolved aerating air gases in the form of small bubbles distributed in the volume of the diffuser 10 rise up the gaps of the package of polymer gas-permeable membranes 6, performing the function of a gas lift pump that continuously transfers thin layers of the working fluid through the gas distribution device 5.

On the fermentation process control controller 39, the frequency of operation of the diaphragm pump 12, the upper and lower pH values of the working fluid, the parameters of the exhaust gases flowing through the gas analyzer 30, the discharge time of the fermentation products, the operating temperature of the heat exchange jacket 4 are set, and the bioreactor operation algorithm is used.

Upon contact of the working fluid with the level sensor 29, the pump 12 is turned on, pumping the working fluid from the capacity of the separator 11 back into the bioreactor, which intensifies the process of separation of gases from the working fluid and eliminates the stagnant zones of the working fluid.

In the process of growth of microorganisms, upon reaching a predetermined lower pH of the working fluid, the pump 12 is turned off, the valve 27 is opened and the resulting fermentation products are discharged from the gas separator 11 to the consumer for a predetermined time.

After a predetermined time for draining the fermentation products, the valve 27 closes, the valve 23 opens, and the next portion of the water-mineral medium is introduced into the bioreactor until it contacts the level sensor 29.

The process of fractional draining and loading of the water-mineral medium is repeated until the predetermined upper pH value of the working medium is restored, after which a pause is maintained during which the pH of the working fluid decreases to the specified lower value.

Maintaining a predetermined ratio of dissolved gases in the working fluid is carried out at a constant pressure of methane in the gas-permeable membranes 6 and when regulating the flow of air and carbon dioxide through feedback installed between the analyzer 30 of the exhaust gases, the electronic regulator 17 of the flow of aeration air through the valve 24 and the electronic regulator 18 of the flow carbon dioxide through the valve 25, at the given values of CH ₄ , O ₂ , CO ₂ .

The damper 15, placed in the pipeline at the outlet of the gas-liquid mixture from the bioreactor, allows you to change the pressure of the working fluid in the bioreactor by changing the flow area and, as a result, control the dissolution rate of the supply gas.

The advantages of the bioreactor over known analogues

1. The gas distribution device is made in the form of a multi-channel gas lift pump pumping thin layers of the working fluid over multiple surfaces of polymer gas-permeable membranes, which increases the dissolution rate of the feed gases and activates the enzymatic reactions.

2. Methane enters the working fluid saturated with oxygen through diffusion through the walls of multiple membranes uniformly distributed throughout the working volume and is completely consumed by microorganisms, which eliminates the creation of explosive gas ratios in the bioreactor.

3. The separator of the exhaust gases from the liquid fermentation products is equipped with a liquid level sensor, which optimizes the control of weaning-topping processes.

4. The input of the water-mineral solution into the bioreactor is carried out in the volume determined by the contact with the level sensor fixed in the tank of the gas separator.

5. The pump pumping the working fluid from the gas separator tank back to the bioreactor turns on when the working fluid contacts the level sensor, and turns off at the set lower value of the pH sensor, which eliminates the stagnant zones of the working fluid.

6. Draining of fermentation products is carried out upon reaching a predetermined lower pH value according to a temporary algorithm, after which the next introduction of a water-mineral medium into the bioreactor is performed.

7. Fractional discharge of fermentation products is carried out until the specified upper pH value of the working fluid is restored, after which the drain is stopped and a temporary pause is maintained until the next decrease in the pH of the working fluid.

8. Management of the ratio of gases in the working fluid is carried out according to the testimony of the exhaust gases flowing through the analyzer CH ₄ , O ₂ , CO ₂ through the feedback control electronic flowmeters of air and carbon dioxide.

9. The heat exchanger is made in the form of a heat exchange jacket having an enlarged heat exchange surface compared to the analogue, and provides better heat transfer.

10. The bioreactor is made in the form of a fermentation module that provides direct scaling of the working volume or extensive extension of bioreactors in the conditions of constructing a cascade of fermentation modules.

These advantages can improve the performance and explosion safety of the bioreactor.

Claims (3)

1. Bioreactor with a membrane device for gas supply of microorganisms, containing a cylindrical body, cover, bottom, heat exchanger, gas distribution device, methane collector, tubular gas-permeable polymer membranes, nozzles for the flow of working fluid and gases, characterized in that the gas distribution device is equipped with guide plates and a diffuser aerating air and made in the form of a multi-channel gas lift pump pumping the working fluid through the surface of the pipes of the polymer gas membranes and the surface of the heat exchanger, made in the form of a heat exchange jacket, the bioreactor further comprises an aerator located in the cavity of the diffuser, for introducing atmospheric air into the working fluid in the form of a finely divided fraction, the methane collector is provided with perforated holes for the free flow of the gas-liquid mixture through the gas distribution device, the separator of the outgoing gases from liquid fermentation products, made in the form of a tank equipped with a working fluid level sensor and a pipeline, Connects the lower part of the container stripper to the bottom part of the bioreactor, the exhaust gas analyzer of CH _4, O _2, CO _2, sensors pH T ° C, electronic flow of air and carbon dioxide, methane pressure regulator and fermentation controller process, the methane reservoir communicates a pipeline with a methane pressure regulator, the aerator through a bacterial filter and electronic flow meters connected to sources of compressed air and carbon dioxide; a separator of exhaust gases from liquid fermentation products is in communication with the upper cavity of the bioreactor through an adjustable damper; and the gas analyzer is in communication with the separator of exhaust gases from liquid fermentation products through a bacterial filter. 2. The bioreactor according to claim 1, characterized in that it further comprises a pump for pumping the working fluid from the separator tank to the bottom of the bioreactor body. 3. The bioreactor according to claim 1, characterized in that the gas distribution device is held in an upright position by means of the guide plates of the gas distribution device and supported by the bottom of the bioreactor.

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