Reactor for fixing CO2 in fermentation tail gas through coupling of microalgae culture and fermentation

Abstract

The invention provides a reactor for coupling fixation of CO2 in fermentation tail gas in microalgae culture and fermentation. The reactor comprises a material supplementing tank, a material supplementing pump, a bioethanol fermentation tank and a microalgae photobioreactor, the material supplementing tank is communicated with the bioethanol fermentation tank through a first pipeline, and the material supplementing pump is arranged on the pipeline; the bioethanol fermentation tank is communicated with the microalgae photobioreactor through a second pipeline; a microalgae culture medium and a cold light source illumination assembly are arranged in the microalgae photobioreactor. The reactor provided by the invention can fix CO2 generated in the ethanol continuous fermentation process through microalgae, the microalgae growth and carbon fixation rate is high, and the reactor has a relatively good treatment effect on CO2 generated in the ethanol fermentation process.

Description

Technical Field

[0001] The present invention relates to the field of bioengineering technology, and in particular to a reactor for coupling microalgae culture and fermentation to fix CO2 in fermentation tail gas, and in particular to a reactor for coupling microalgae culture and bioethanol fermentation to fix CO2 in fermentation tail gas. Background Art

[0002] Biofuel ethanol refers to ethanol that can be used as fuel by fermenting renewable biomass through microorganisms. It can improve the traditional energy structure and promote global energy transformation. In the fermentation process of bioethanol, the fermentation substrate is converted into ethanol and CO2 gas through yeast glycolysis and anaerobic degradation of pyruvate. The overall reaction equation is as follows:

[0003] C6H 12 O6→2C2H5OH+2CO2

[0004] CO2 gas is the most important by-product in the ethanol fermentation process. According to molecular weight calculation, 49% of the total sugar flows to the generation of CO2, which greatly reduces the utilization rate of fermentation substrates. Since yeast cell growth and by-product generation also release CO2, the production of fuel ethanol is almost equal to CO2. Theoretically, 0.95 tons of CO2 can be produced for 1 ton of ethanol. In actual industrial production, the concentration of CO2 gas in the tail gas of bioethanol fermentation is very high, reaching more than 99%. Other impurities are alcohols, aldehydes, esters and trace oxygen.

[0005] At present, fuel ethanol has developed into the world's largest and most widely used renewable energy. my country's biofuel ethanol production ranks after the United States and Brazil, and it is the world's third largest producer and user of biofuel ethanol. In 2021, my country's fuel ethanol production was 870 million gallons. As the production of bioethanol increases, CO2 emissions also increase. Leaving it to natural emissions not only wastes this resource, but also aggravates the greenhouse effect. Since the 21st century, global carbon emissions have accelerated sharply, with global CO2 emissions increasing by 40% from 2000 to 2019. Calculated by mass, CO2 is by far the largest greenhouse gas emission. This problem needs to be solved urgently to maintain the sustainable green development of bioethanol and achieve the goal of zero carbon emissions for biofuel ethanol by the middle of this century.

[0006] Carbon capture utilization and storage (CCUS) is considered to be the only technical means to achieve large-scale reduction of CO2 emissions and is also one of my country's key technologies. Compared with physical and chemical methods, biological fixation of CO2 is a relatively cost-effective and environmentally friendly method. Photosynthetic organisms absorb CO2 through photosynthesis and play a key role in maintaining the balance of atmospheric CO2.

[0007] Microalgae are a type of microorganism that contains chlorophyll and can perform photosynthesis. Marine plankton represented by microalgae fixes about 52 billion tons of CO2 each year, accounting for half of the global primary productivity. Microalgae have a large specific surface area, and their photosynthetic efficiency and carbon fixation rate far exceed those of terrestrial plants. The photosynthetic efficiency is as high as 12%. In addition, microalgae have a special CO2 assimilation mechanism, called the carbon concentrating mechanism (CCM), which can efficiently absorb and fix CO2. These characteristics enable microalgae to have a very high carbon fixation rate. Every 1kg of microalgae cultured can absorb 1.83kg of CO2, which has great development potential. CO2 fixation based on microalgae is considered to be one of the most promising and sustainable carbon capture, utilization and storage technologies (CCUS).

[0008] Microalgae photobioreactors have an extremely important influence on the growth of microalgae and the fixation of CO2. At present, there are few reports on the coupling of microbial fermentation systems and microalgae culture systems to achieve CO2 fixation. In the relevant existing literature, an airlift flat-plate reactor is used as a microalgae photobioreactor. The aeration effect of this reactor is average, the contact between the fermentation tail gas and the microalgae is not sufficient, and some microalgae cells will also settle to the bottom of the reactor, which is extremely unfavorable for the growth of microalgae and the fixation and utilization of CO2. Summary of the invention

[0009] In view of the defects in the prior art, the object of the present invention is to provide a reactor for coupling microalgae cultivation and fermentation to fix CO2 in fermentation tail gas.

[0010] According to the present invention, a reactor for microalgae culture and fermentation coupling to fix CO2 in fermentation tail gas comprises: a feed tank, a feed pump, a bioethanol fermentation tank and a microalgae photobioreactor;

[0011] The feed tank is connected to the bioethanol fermentation tank through a first pipeline, and the feed pump is arranged on the pipeline; the bioethanol fermentation tank is connected to the microalgae photobioreactor through a second pipeline;

[0012] A microalgae culture medium and a cold light source illumination component are arranged in the microalgae photobioreactor.

[0013] Preferably, the feed replenishment tank is provided with a first air inlet pipe, a filter membrane is provided in the first air inlet pipe, and the feed replenishment tank is connected with the outside air through the filter membrane.

[0014] Preferably, the bioethanol fermentation tank is provided with a second air inlet pipe, a filter membrane is provided in the second air inlet pipe, and the bioethanol fermentation tank is connected to the outside air through the filter membrane.

[0015] Preferably, the second air inlet pipe is arranged in an "L" shape;

[0016] The vertical pipe portion of the second air inlet pipe is connected to the bioethanol fermentation tank, the horizontal pipe portion of the second air inlet pipe is arranged close to the bottom of the bioethanol fermentation tank, and a plurality of first air outlets are arranged on the horizontal pipe portion of the second air inlet pipe.

[0017] Preferably, a first agitator is provided in the bioethanol fermentation tank.

[0018] Preferably, a third air inlet pipe is provided on the second pipe, a one-way valve and a filter membrane are provided in the third air inlet pipe, and external air passes into the second pipe through the one-way valve and the filter membrane.

[0019] Preferably, the cold light source illumination component is an LED light strip, and the LED light strip is wound around the surface of the microalgae photobioreactor.

[0020] Preferably, when the microalgae photobioreactor is in operation, the light intensity at the center of the microalgae photobioreactor reaches 180 μmol m -2 s -1 The light intensity close to the inner wall of the microalgae photobioreactor reaches 250 μmol m - 2 s -1 .

[0021] Preferably, a second agitator with a CO2 ventilation pipeline is provided in the microalgae photobioreactor;

[0022] The CO2 ventilation pipeline is connected to the second pipeline, and the CO2 ventilation pipeline is arranged close to the bottom of the microalgae photobioreactor. A plurality of second gas outlets are distributed on the bottom transverse pipe of the CO2 ventilation pipeline.

[0023] Preferably, the microalgae photobioreactor is further provided with an exhaust pipe, a filter membrane is detachably provided in the exhaust pipe, and the microalgae photobioreactor is connected to the outside air through the filter membrane.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The reactor provided by the present invention can fix the CO2 continuously produced during the bioethanol fermentation process through microalgae, thereby achieving efficient fixation of CO2 in the fermentation tail gas;

[0026] 2. The reactor provided by the present invention has a stirring function coupled with a ventilation system, so that the microalgae are evenly distributed in the reactor, avoiding the agglomeration and sedimentation of algae cells, improving the light absorption rate, having a stronger aeration effect, and more sufficient contact between the fermentation tail gas and the algae cells, thereby enhancing the absorption and fixation of CO2 by the microalgae cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0028] Figure 1 It is a structural diagram of a reactor for microalgae cultivation and fermentation coupled with fixation of CO2 in fermentation tail gas of the present invention;

[0029] Figure 2 It is a growth curve comparison diagram of Example 4 and Comparative Example 1;

[0030] Figure 3 It is a schematic diagram of the CO2 concentration of each gas (fermentation tail gas, Scenedesmus sp. FSP-3 culture inlet and outlet gas) during the cultivation process of the microalgae cultivation and ethanol fermentation coupling system in Example 4.

[0031] The figure shows:

[0032] Feed tank 1 LED light strip 8

[0033] First air inlet pipe 2 Second stirrer 9

[0034] Feed pump 3 Exhaust pipe 10

[0035] Second intake pipe 4 First pipe 11

[0036] Vertical pipe section 401 Second pipe belt 12

[0037] Horizontal tube 402 First air outlet 13

[0038] Bioethanol fermentation tank 5 Second vent 14

[0039] Third air intake pipe 6 CO2 ventilation pipe 15

[0040] Microalgae photobioreactor 7 First agitator 16 DETAILED DESCRIPTION

[0041] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0042] Embodiment 1:

[0043] like Figure 1 As shown, this embodiment provides a reactor for microalgae cultivation and fermentation coupling and fixation of CO2 in fermentation tail gas, comprising: a feed tank 1, a feed pump 3, a bioethanol fermentation tank 5 and a microalgae photobioreactor 7, the feed tank 1 is connected to the bioethanol fermentation tank 5 through a first pipe 11, the feed pump 3 is arranged on the pipe, the bioethanol fermentation tank 5 is connected to the microalgae photobioreactor 7 through a second pipe 12, and a microalgae culture medium and a cold light source illumination component are arranged in the microalgae photobioreactor 7.

[0044] A first stirrer 16 is provided in the bioethanol fermentation tank 5. The cold light source illumination component is an LED light strip 8, and the surface of the microalgae photobioreactor 7 is wound with the LED light strip 8. When the microalgae photobioreactor 7 is working, the light intensity at the center of the microalgae photobioreactor 7 reaches 180 μmol m -2 s -1 The light intensity close to the inner wall of the microalgae photobioreactor 7 reached 250 μmol m -2 s -1 .

[0045] A first air inlet pipe 2 is provided on the feed tank 1, a filter membrane is provided in the first air inlet pipe 2, and the feed tank 1 is connected with the outside air through the filter membrane.

[0046] The bioethanol fermentation tank 5 is provided with a second air inlet pipe 4, in which a filter membrane is detachably provided, and the bioethanol fermentation tank 5 is connected to the outside air through the filter membrane. The second air inlet pipe 4 is arranged in an "L" shape, and a vertical pipe portion 401 of the second air inlet pipe 4 is connected to the bioethanol fermentation tank 5, and a horizontal pipe portion 402 of the second air inlet pipe 4 is arranged near the bottom of the bioethanol fermentation tank 5, and a plurality of first air outlets 13 are arranged on the horizontal pipe portion 402 of the second air inlet pipe 4.

[0047] The second pipeline 12 is provided with a third air inlet pipe 6 , and a one-way valve and a filter membrane are provided inside the third air inlet pipe 6 , and external air flows into the second pipeline 12 through the one-way valve and the filter membrane.

[0048] The microalgae photobioreactor 7 is also provided with an exhaust pipe 10 , in which a filter membrane is detachably provided, and the microalgae photobioreactor 7 is connected to the outside air through the filter membrane.

[0049] A second agitator 9 with a CO2 ventilation pipe 15 is arranged in the microalgae photobioreactor 7. The CO2 ventilation pipe 15 is connected to the second pipe 12. The CO2 ventilation pipe 15 is arranged close to the bottom of the microalgae photobioreactor 7. A plurality of second gas outlets 14 are distributed on the bottom transverse pipe of the CO2 ventilation pipe 15.

[0050] Embodiment 2:

[0051] Those skilled in the art may understand this embodiment as a more specific description of Embodiment 1.

[0052] This embodiment provides a reactor for coupling microalgae cultivation and ethanol fermentation to fix CO2 in fermentation tail gas, comprising:

[0053] Feed tank 1: used to provide fermentation substrate for continuous anaerobic fermentation of bioethanol fermentation tank 5;

[0054] Feed pump 3: used to pump the fermentation substrate in the feed tank 1 into the bioethanol fermentation tank 5, and the feed tank 1 is connected to the bioethanol fermentation tank 5 through a pipeline;

[0055] Bioethanol fermentation tank 5: used for anaerobic fermentation of the fermentation substrate pumped into the feed tank 1 by yeast to produce ethanol; the fermentation tail gas is transported to the microalgae photobioreactor 7;

[0056] Microalgae photobioreactor 7: It is equipped with microalgae culture medium for cultivating microalgae and absorbing and fixing CO2 in fermentation exhaust gas; it is also equipped with a cold light source illumination system for providing light for the growth of microalgae and reducing the heat release of lamp beads to maintain the growth of microalgae.

[0057] Furthermore, a first air inlet pipe 2 is provided on the feed tank 1, which is connected to the outside air through a (0.22 μm) filter membrane to balance the internal pressure of the feed tank 1. The filter membrane can be disassembled and replaced at any time.

[0058] Furthermore, a second air inlet pipe 4 is provided on the bioethanol fermentation tank 5 to provide oxygen for the growth of yeast in the early stage of fermentation. The air is filtered through a (0.22 μm) filter membrane and then introduced into the fermentation substrate. The second air inlet pipe is in an "L" shape in the fermentation tank, and a plurality of air outlets are distributed on the horizontal pipe at the bottom of the second air inlet pipe to facilitate the full mixing of oxygen into the yeast culture medium.

[0059] Furthermore, a first agitator 16 is provided in the bioethanol fermentation tank 5 .

[0060] Furthermore, the fermentation tail gas delivery pipeline between the bioethanol fermentation tank 5 and the microalgae photobioreactor 7 is provided with a third air inlet pipe 6 for diluting CO 2 in the fermentation tail gas.

[0061] Furthermore, a one-way valve and a filter membrane are provided at the third air inlet pipe 6. The air is filtered through the one-way valve and the (0.22 μm) filter membrane and then introduced into the fermentation tail gas delivery pipeline, mixed with the fermentation tail gas and then introduced into the microalgae culture medium.

[0062] Furthermore, a cold light source LED light strip 8 is wound around the surface of the microalgae photobioreactor 7 as a lighting system. The LED light strip is wound closely to the outer wall of the microalgae photobioreactor to provide light for the growth of the microalgae.

[0063] Furthermore, when the reactor is working, the light intensity at the center of the reactor reaches 180 μmol m -2 s -1 The light intensity near the inner wall of the reactor reached 250 μmol m -2 s -1 ,Efficient light distribution is conducive to breaking through the limitations of light shielding effect of microalgae and promoting the growth and carbon fixation of microalgae.

[0064] Furthermore, a second stirrer 9 combined with a CO2 ventilation pipe is provided in the microalgae photobioreactor 7. The stirring device of the combined ventilation pipe is connected to the bioethanol fermentation tank 5, and a plurality of gas outlets are distributed on the bottom transverse pipe thereof. Through the coupling of stirring and ventilation, the algae in the culture solution are evenly distributed, and the local algae aggregation is avoided to affect the algae cells from receiving light, so that the algae receive light evenly, and the light receiving rate is improved. At the same time, the distribution of CO2 gas in the algae solution is improved, the contact between CO2 and algae cells is increased, and the fixation effect of microalgae on CO2 in the fermentation waste gas is strengthened, so that CO2 can be fully mixed into the microalgae culture system.

[0065] Furthermore, the microalgae photobioreactor 7 is also provided with an exhaust pipe 10, which is connected to the outside air through a (0.22 μm) filter membrane, and the final exhaust gas components can be detected through the exhaust pipe.

[0066] The present embodiment provides a reactor for coupling microalgae cultivation and fermentation to fix CO2 in fermentation tail gas; including a feed tank for feeding in the bioethanol fermentation process; a bioethanol fermentation tank for yeast cultivation and anaerobic fermentation to produce ethanol; a microalgae photobioreactor for microalgae cultivation and fixation of CO2 in fermentation tail gas, which has a stirring system and a lighting system; an LED light strip, which is wrapped tightly around the outer wall of the microalgae photobioreactor to provide light for the growth of microalgae, and serves as a lighting system for the microalgae photobioreactor. The reactor provided in this embodiment can fix the CO2 produced in the continuous fermentation of ethanol by microalgae, and the microalgae has a high growth and carbon fixation rate, and has a good treatment effect on the CO2 produced in the ethanol fermentation process. The present embodiment provides a reactor for coupling microalgae cultivation and fermentation to fix CO2 in fermentation tail gas; including a feed tank for feeding in the bioethanol fermentation process; a bioethanol fermentation tank for yeast cultivation and anaerobic fermentation to produce ethanol; a microalgae photobioreactor for microalgae cultivation and fixation of CO2 in fermentation tail gas, which has a stirring system and a lighting system; an LED light strip, which is wrapped tightly around the outer wall of the microalgae photobioreactor to provide light for the growth of microalgae, and serves as a lighting system for the microalgae photobioreactor. The reactor provided in this embodiment can fix the CO2 produced in the continuous fermentation of ethanol by microalgae, and the microalgae has a high growth and carbon fixation rate, and has a good treatment effect on the CO2 produced in the ethanol fermentation process.

[0067] The purpose of this embodiment is to solve the problem of reusing and fixing a large amount of CO2 generated during bioethanol fermentation, and to provide a reactor for coupling microalgae cultivation and fermentation to fix CO2 in fermentation tail gas; the reactor couples microalgae cultivation and bioethanol fermentation processes to enhance the aeration effect, and utilizes microalgae to efficiently fix the CO2 released during ethanol fermentation, converts it into microalgae biomass, and improves the utilization rate of fermentation substrates.

[0068] Embodiment 3:

[0069] Those skilled in the art may understand this embodiment as a more specific description of Embodiment 1 and Embodiment 2.

[0070] This embodiment provides a reactor for coupling microalgae cultivation and fermentation to fix CO2 in fermentation tail gas, such as Figure 1 The following include:

[0071] Feed tank 1: used to provide fermentation substrate for continuous anaerobic fermentation of bioethanol fermentation tank 5; the culture medium in feed tank 1 is pumped into bioethanol fermentation tank 5 through a feed pipeline connected to feed pump 3; the first air inlet pipe 2 of feed tank 1 is connected to the outside air through a 0.22μm filter membrane to balance the internal pressure of feed tank 1.

[0072] Bioethanol fermentation tank 5: used for anaerobic fermentation of yeast to produce ethanol; the anaerobic fermentation process here can be implemented using the brewer's yeast in the prior art; the fermentation process uses YPD culture medium as the matrix; the bioethanol fermentation tank 5 has a second air inlet pipe 4. The second air inlet pipe is in an "L" shape in the fermentation tank, and a number of air outlets are distributed on the bottom transverse pipe of the second air inlet pipe to facilitate the full mixing of oxygen into the yeast culture medium. In the early stage of fermentation, the air is filtered through a 0.22μm filter membrane and then passed into the culture medium at a rate of 1vvm. The brewer's yeast performs aerobic respiration and grows and reproduces rapidly. After the growth enters the plateau period, the ventilation rate is reduced to 0.1vvm, and the facultative anaerobic fermentation is turned into to produce a large amount of ethanol and CO2.

[0073] The third air inlet pipe 6 is used to dilute the CO2 concentration in the fermentation tail gas, with a dilution ratio of 1:10; the air is introduced into the system after being filtered through a one-way valve and a 0.22 μm filter membrane, and then mixed with the fermentation tail gas, and after being diluted to a suitable concentration, it is introduced into the microalgae photobioreactor 7 through the ventilation pipeline between the reactors.

[0074] Microalgae photobioreactor 7: used for culturing microalgae and absorbing and fixing CO2 in fermentation tail gas; the diluted fermentation tail gas is introduced into the microalgae culture solution in the microalgae photobioreactor 7, and CO2 is absorbed and utilized by the microalgae; a cold light source LED light strip 8 is wrapped around the surface of the microalgae photobioreactor 7 to provide sufficient light for the growth of the microalgae; the microalgae photobioreactor 7 has a second agitator 9 combined with the air inlet pipeline, and a plurality of air outlets are distributed on the bottom transverse tube thereof, which can ventilate while stirring, so that the algae in the culture solution are evenly distributed, avoid local algae aggregation and affect the algae cells from receiving light, make the algae receive light evenly, improve the light receiving rate, and at the same time improve the distribution of CO2 gas in the algae solution, increase the contact between CO2 and algae cells, and strengthen the fixation effect of microalgae on CO2 in the fermentation waste gas; the algae used here can be algae that can fix CO2 in the prior art, and the present invention is not specifically limited, for example, Scenedesmus, Chlorella, etc. can be used; in order to improve the effect of microalgae fixing CO2, 5mmol L -1 The CO2 dissolution agent propylene carbonate can increase the solubility of CO2 in the culture medium; an exhaust pipe 10 is also provided on the microalgae photobioreactor 7, and the exhaust pipe 10 is connected to the outside air through a 0.22 μm filter membrane, and the final exhaust gas components can be detected through this exhaust pipe.

[0075] The feed tank 1, the bioethanol fermentation tank 5, and the microalgae photobioreactor 7 are connected in sequence to form a coupling system. The fermentation tail gas is directly introduced into the microalgae culture solution after being diluted, and CO2 is absorbed and fixed by the microalgae.

[0076] Embodiment 4:

[0077] Those skilled in the art may understand this embodiment as a more specific description of Embodiment 2 and Embodiment 3.

[0078] Prepare 200g L -1 Glucose solution was sterilized at 115°C for 20 min and added to the feed tank.

[0079] 2L YPD medium was prepared and added to the bioethanol fermenter for ethanol fermentation. YPD medium (g L -1 ): Glucose 100, yeast powder 10, peptone 10, sterilize at 115℃ for 20min.

[0080] The yeast used in the ethanol fermentation was Saccharomyces cerevisiae BY4741 (purchased), with an inoculation amount of 10%, an aeration rate of 0.1 vvm, and an agitation rate of 100 rpm. The continuous fermentation produced ethanol and CO2.

[0081] The feeding strategy of the feeding pump was set as follows: 200 mL of 20% glucose was fed every 12 h to provide sufficient substrate for ethanol fermentation.

[0082] The algae species cultured in the microalgae photobioreactor was Scenedesmus sp. FSP-3 (HO SH, CHEN CY, YEH KL, et al. Characterization of photosynthetic carbon dioxide fixationability of indigenous Scenedesmus obliquus isolates [J]. Biochemical Engineering Journal, 2010, 53 (1): 57-62. doi: 10.1016 / j.bej.2010.09.006). The culture medium volume in the microalgae photobioreactor was 3 L, and the inoculation concentration was 0.2 g L -1 .

[0083] The medium used for the cultivation of Scenedesmus sp. FSP-3 was BG11 medium, and 5 mmol L -1 The CO2 solvent was propylene carbonate, the temperature was controlled at 25 °C, the stirring rate was 250 rpm, and the light intensity reached 180 μmol m at the center of the reactor for 24 h. -2 s -1 The light intensity near the inner wall of the reactor reached 250 μmol m - 2 s -1, which is enough to provide light for the growth of Scenedesmus sp.FSP-3.

[0084] The feeding tank, bioethanol fermentation tank and microalgae photobioreactor are connected in sequence. The CO2 produced by the bioethanol fermentation tank is diluted 1:10 and then directly introduced into the microalgae photobioreactor to provide CO2 for the growth of Scenedesmus sp. FSP-3, and CO2 is effectively absorbed and fixed by Scenedesmus sp. FSP-3.

[0085] The coupled system was operated for 4 days to measure the growth rate and carbon fixation rate of Scenedesmus sp. FSP-3, as well as the fermentation tail gas, the inlet and outlet gases of Scenedesmus sp. FSP-3 culture, and the CO2 absorption rate was calculated.

[0086] Comparative Example 1:

[0087] The difference from Example 4 is that the cultivation of Scenedesmus sp. FSP-3 is not coupled with a bioethanol fermenter, and air is introduced during the cultivation process instead of fermentation exhaust gas.

[0088] Scenedesmus sp. FSP3 CO2 fixation process:

[0089] Its growth rate (P overall , g L -1 d -1 ) by the change of biomass concentration (ΔC, g L) within a certain culture time (Δt, d) -1 ) is calculated by the following formula:

[0090]

[0091] CO2 fixation rate R CO2 (g L -1 d -1 ) is calculated by the following formula:

[0092]

[0093] Among them, fc is the C content in microalgae cells, Mc is the relative molecular mass of C, and M CO2 is the molecular weight of CO2. 1.83 O 0.48 N 0.11 P 0.01 As the molecular formula of microalgae biomass, the value of fc is 0.51.

[0094] The CO2 absorption efficiency (ηCO2) can be calculated by the following formula:

[0095]

[0096] Among them, C CO2,in is the concentration of gaseous CO2 introduced into the reactor during the cultivation of Scenedesmus sp. FSP3, C CO2,out is the CO2 concentration in the gas leaving the reactor.

[0097] The growth curves in Example 4 and Reference Example 1 are as follows Figure 2 As shown, after 4 days of cultivation, the biomass concentration of control example 1 was 0.84 g L -1 The overall growth rate was 0.17 g L -1 d -1 ; The biomass concentration of Example 1 reached 2.00 g L -1 The overall growth rate was 0.46 g L -1 d -1 The carbon fixation rate is 0.86 g L -1 d -1 The ethanol fermentation process was coupled with the microalgae cultivation process, and the growth of Scenedesmus sp. FSP-3 was significantly promoted under the action of fermentation exhaust gas.

[0098] The CO2 absorption in the coupled system is as follows Figure 3 As shown, the average CO2 absorption efficiency of Scenedesmus sp. FSP-3 algae liquid during the cultivation process reached 37.21%, and the maximum CO2 absorption efficiency was as high as 47.37%, which proves that the coupling system of microalgae cultivation and ethanol fermentation has a good treatment effect on the CO2 produced during the ethanol fermentation process.

[0099] The reactor provided by the present invention can fix CO2 generated during the continuous fermentation of ethanol through microalgae. The microalgae has high growth and carbon fixation rates and has a good treatment effect on the CO2 generated during the ethanol fermentation process.

[0100] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0101] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A reactor for coupling microalgae cultivation and fermentation to fix CO2 in fermentation tail gas, characterized in that: include: A feed tank (1), a feed pump (3), a bioethanol fermentation tank (5) and a microalgae photobioreactor (7); The feed tank (1) is connected to the bioethanol fermentation tank (5) via a first pipeline (11), and the feed pump (3) is arranged on the pipeline; the bioethanol fermentation tank (5) is connected to the microalgae photobioreactor (7) via a second pipeline (12); A microalgae culture medium and a cold light source illumination component are arranged in the microalgae photobioreactor (7).

2. The reactor for microalgae cultivation and fermentation coupled with fixation of CO2 in fermentation tail gas according to claim 1, characterized in that: The feed replenishment tank (1) is provided with a first air inlet pipe (2), a filter membrane is provided in the first air inlet pipe (2), and the feed replenishment tank (1) is connected to the outside air through the filter membrane.

3. The reactor for microalgae cultivation and fermentation coupled with fixation of CO2 in fermentation tail gas according to claim 1, characterized in that: The bioethanol fermentation tank (5) is provided with a second air inlet pipe (4), a filter membrane is provided in the second air inlet pipe (4), and the bioethanol fermentation tank (5) is connected to the outside air through the filter membrane.

4. The reactor for coupling microalgae cultivation and fermentation and fixing CO2 in fermentation tail gas according to claim 3, characterized in that: The second air inlet pipe (4) is arranged in an "L" shape; The vertical pipe portion (401) of the second air inlet pipe (4) is connected to the bioethanol fermentation tank (5), the horizontal pipe portion (402) of the second air inlet pipe (4) is arranged close to the bottom of the bioethanol fermentation tank (5), and a plurality of first air outlets (13) are arranged on the horizontal pipe portion (402) of the second air inlet pipe (4).

5. The reactor for coupling microalgae cultivation and fermentation and fixing CO2 in fermentation tail gas according to claim 1, characterized in that: A first agitator (16) is arranged in the bioethanol fermentation tank (5).

6. The reactor for microalgae cultivation and fermentation coupled with fixation of CO2 in fermentation tail gas according to claim 1, characterized in that: The second pipeline (12) is provided with a third air inlet pipe (6), and a one-way valve and a filter membrane are provided in the third air inlet pipe (6), and external air flows into the second pipeline (12) through the one-way valve and the filter membrane.

7. The reactor for microalgae cultivation and fermentation coupled with fixation of CO2 in fermentation tail gas according to claim 1, characterized in that: The cold light source illumination component is an LED light strip (8), and the LED light strip (8) is wound around the surface of the microalgae photobioreactor (7).

8. The reactor for coupling microalgae cultivation and fermentation and fixing CO2 in fermentation tail gas according to claim 7, characterized in that: When the microalgae photobioreactor (7) is in operation, the light intensity at the center of the microalgae photobioreactor (7) reaches 180 μmol m -2 s -1 The light intensity close to the inner wall of the microalgae photobioreactor (7) reaches 250 μmol m -2 s -1 .

9. The reactor for microalgae cultivation and fermentation coupled with fixation of CO2 in fermentation tail gas according to claim 1, characterized in that: A second agitator (9) with a CO2 ventilation pipeline (15) is arranged in the microalgae photobioreactor (7); The CO2 ventilation pipeline (15) is connected to the second pipeline (12), and the CO2 ventilation pipeline (15) is arranged close to the bottom of the microalgae photobioreactor (7). A plurality of second air outlets (14) are distributed on the bottom transverse pipe of the CO2 ventilation pipeline (15).

10. The reactor for coupling microalgae cultivation and fermentation and fixing CO2 in fermentation tail gas according to claim 1, characterized in that: The microalgae photobioreactor (7) is also provided with an exhaust pipe (10), a filter membrane is detachably provided in the exhaust pipe (10), and the microalgae photobioreactor (7) is connected to the outside air via the filter membrane.

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