A raceway pool photobioreactor for promoting carbon source absorption by ammonia nitrate and its use method

Abstract

The present invention discloses a raceway pool photobioreactor for promoting carbon source absorption by ammonia nitrate, comprising a raceway pool body, a partition wall arranged in the raceway pool body, a pH sensor, a stirring paddle for promoting algae liquid to flow in a ring along the raceway pool body, a carbon replenishing device for adjusting the pH value of the algae liquid, and an ammonia water replenishing device for replenishing ammonia water; the partition wall isolates the raceway pool body into an annular channel; the pH sensor is located between the carbon replenishing device and the ammonia water replenishing device; the ammonia water replenishing device is located upstream of the carbon replenishing device.

Description

Technical Field

[0001] The invention relates to the field of microalgae cultivation, and in particular to a raceway pool photobioreactor for promoting carbon source absorption by ammonia nitrate and a use method thereof. Background Art

[0002] Microalgae are a type of photosynthetic autotrophic microorganisms that can produce a variety of chemicals by fixing CO2. Some can produce fatty hydrocarbons, such as grape algae, which can produce hydrocarbons of 15% to 75% of the cell dry weight. Some can accumulate glycogen, some can accumulate glycerol, and the oil of many microalgae can reach more than 60% of the dry weight. Due to its fast growth rate and the ability to use wastewater and waste gas for cultivation, it has received more and more attention worldwide.

[0003] At present, the cultivation methods of microalgae are mainly divided into open raceway pool cultivation and closed photobioreactor cultivation. Both of them mostly introduce carbon dioxide-containing gas into the culture solution as a carbon source in a bubbling manner, but the problem with this method is that the carbon dioxide absorption rate is low, which leads to low carbon dioxide utilization and high carbon source cost. In addition, a large amount of nitrogen source is required in the process of microalgae cultivation. The traditional nitrogen source is nitrate, such as sodium nitrate. However, after the microalgae absorbs and metabolizes nitrate, sodium ions increase the salinity of the culture solution, which has an adverse effect on the recycling of the culture medium. Therefore, in order to meet the rapid growth needs of microalgae and reduce the cultivation cost at the same time, it is necessary to improve the utilization rate of carbon dioxide on the one hand, and replace the nitrogen source on the other hand.

[0004] Patents CN200510126465.2, CN201210138598.1 and CN201210138845.8, from the perspective of extending the gas-liquid contact time and increasing the gas-liquid contact area, invented the trap-type carbon supplementation technology and the horizontal immersion carbon supplementation technology for supplementing CO2 in an open pool. This technology strengthens the mass transfer process and greatly improves the absorption rate of CO2. However, the above patents change the flow direction of the culture solution in the runway pool by setting a carbon supplementation trap before or after the stirring paddle. The liquid greatly increases the energy consumption of the drive in the process of flowing into the trap and then flowing out. In addition, the culture solution exchanged with the gas in the horizontal immersion hood carbon supplementation technology is limited, and the carbon dioxide bubbles that are not completely absorbed will accumulate on the inner wall of the hood. When the liquid flow rate increases, it will escape into the air again. The inventor carefully studied the consumption law of carbon source and nitrogen source in the culture solution and found that replacing the nitrate nitrogen source with ammonia water can fix carbon dioxide while reducing the cost of water resource recycling treatment, and will not cause toxicity to microalgae cells. Summary of the invention

[0005] The object of the present invention is to provide a raceway pool photobioreactor in which ammonia nitrate is used to promote carbon source absorption, so as to solve the problems of low utilization rate of carbon dioxide and high cost of reactor water circulation treatment in the prior art.

[0006] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a raceway pool photobioreactor for promoting carbon source absorption by ammonia nitrate, comprising a raceway pool body, a partition wall arranged in the raceway pool body, a pH sensor, a stirring paddle, a carbon replenishing device for adjusting the pH value of the algae liquid, and an ammonia water replenishing device for replenishing ammonia water; the stirring paddle is installed in the raceway pool body to promote the algae liquid to flow in a ring along the raceway pool body; the partition wall isolates the raceway pool body into an annular channel; the pH sensor is located between the carbon replenishing device and the ammonia water replenishing device; the ammonia water replenishing device is located upstream of the carbon replenishing device.

[0007] Furthermore, the ammonia water replenishing device includes an ammonia water storage tank, a delivery pump, and a delivery main pipe arranged in the runway pool body; the ammonia water storage tank and the delivery pump are both arranged outside the runway pool body; the inlet of the delivery pump is connected to the ammonia water storage tank through a pipeline, and the outlet thereof is connected to the delivery main pipe; the delivery main pipe is immersed in the algae liquid, and a plurality of nozzles are arranged on the delivery main pipe.

[0008] Furthermore, the nozzle is arranged toward the carbon replenishing device.

[0009] Furthermore, the carbon replenishing device is a well-type carbon replenishing device or a horizontal immersion type carbon replenishing device.

[0010] Another aspect of the present invention discloses a method for using a raceway pool photobioreactor for promoting carbon source absorption by ammonia nitrate.

[0011] a. Add culture medium into the reactor and sterilize it, wherein the depth of the culture medium is 5 cm to 30 cm; the culture medium is one of Zarrouk culture medium, F / 2 culture medium, SM culture medium, D1 culture medium and BG11 culture medium without any addition;

[0012] b. Start the stirring paddle to stir the culture medium evenly, and inoculate the microalgae species into the culture medium, wherein the inoculation density of the microalgae species is between 0.01 g / L and 0.5 g / L calculated on a dry basis; adjust the speed of the stirring paddle so that the flow rate of the culture medium is between 10 cm / s and 100 cm / s;

[0013] c. Start the delivery pump in the ammonia water adding device to add ammonia water to the algae liquid to maintain the NH4 + The concentration is 2mmol / L to 4mmol / L;

[0014] d. According to the pH value of the culture medium detected by the pH sensor, when the pH value is higher than the pH value required for microalgae culture, the carbon supplement device is turned on to add carbon dioxide into the algae liquid; when the pH value is lower than the pH value required for microalgae culture, the carbon supplement device is turned off;

[0015] e. Detect the cell concentration of the microalgae, and harvest the microalgae when the cell concentration of the microalgae does not change for two consecutive days.

[0016] In the above method, further, the disinfection medium used when disinfecting the culture medium is one of ultraviolet rays, sodium hypochlorite, and ozone.

[0017] Beneficial effects of the present invention: 1. The reactor of the present invention is provided with an ammonia water feeding device, and ammonia water is used to replace nitrate as the nitrogen source in the culture medium to cultivate microalgae, which can reduce the depth of the carbon replenishment trap while improving the utilization rate of the carbon source, and can effectively reduce the energy consumption of the stirring paddle to drive the circulation of the algae liquid.

[0018] 2. The use of the reactor of the present invention for microalgae cultivation can reduce the salinity of the culture solution, increase the number of times the culture solution is recycled, and save water treatment costs.

[0019] 3. The present invention adopts the method of directly adding ammonia water as the nitrogen source for supplementation, and the ammonia water supplementing device is arranged upstream of the carbon supplementing device. The ammonia water enters the algae liquid and directly reacts with the carbon dioxide to be fixed. The operation is convenient and the steps are simple, and the escape of ammonia is reduced, thereby improving the yield of the nitrogen source. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the present invention;

[0021] Figure 2 This is a schematic diagram of the AA structure of Example 1 of the present invention;

[0022] Figure 3 AA direction structural schematic diagram of embodiment 2 of the present invention;

[0023] Figure numerals: 1-runway pool body; 2-isolation wall; 3-wheel impeller; 4-carbon replenishing device; 41-trap type carbon replenishing device; 42-horizontal immersion type carbon replenishing device; 411-carbon dioxide aeration device; 5-pH sensor; 6-delivery main pipe; 7-delivery pump; 8-ammonia storage tank; 9-nozzle. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0025] Embodiment 1:

[0026] A raceway pool photobioreactor for promoting carbon source absorption by ammonia nitrate, comprising a raceway pool body 1, a partition wall 2 arranged in the raceway pool body 1, a pH sensor 5, a stirring paddle 3, a carbon replenishing device 4 for adjusting the pH value of algae liquid, and an ammonia water replenishing device for replenishing ammonia water; the raceway pool body 1 has a circumference of 70 meters and a width of 3 meters. The stirring paddle 3 is installed in the raceway pool body 1 and connected to the output end of the motor arranged outside the raceway pool, and is used to promote the algae liquid to flow in a circular manner along the raceway pool body 1. The partition wall 2 is arranged in the center of the raceway pool body 1, isolating the raceway pool body 1 into a ring channel; the pH sensor 5 is located between the carbon replenishing device 4 and the ammonia water replenishing device; the ammonia water replenishing device is located upstream of the carbon replenishing device 4. The ammonia water replenishing device includes an ammonia water storage tank 8, a delivery pump 7, and a delivery main pipe 6 arranged in the runway pool body 1; the ammonia water storage tank 8 and the delivery pump 7 are both arranged outside the runway pool body 1; the inlet of the delivery pump 7 is connected to the ammonia water storage tank 8 through a pipeline, and its outlet is connected to the delivery main pipe 6; the delivery main pipe 6 is immersed in the algae liquid, and a plurality of nozzles 9 are arranged on the delivery main pipe 6. The nozzle 9 is arranged toward the carbon replenishing device 4. The carbon replenishing device 4 is a well-type carbon replenishing device 41. The well-type carbon replenishing structure is the structure in Example 1 in the prior art CN201210138598.1, and the difference is that the depth of the carbon replenishing well in this embodiment is 30 cm. The specific structure will not be repeated here.

[0027] Add culture medium to the runway pool and disinfect it with sodium hypochlorite. The added culture medium is BG11 culture medium without nitrogen source. Start the stirring paddle 3 to stir the culture medium evenly. Inoculate the microalgae species into the culture medium. Start the motor to drive the stirring paddle to stir the culture medium evenly. Inoculate the microalgae species into the culture medium. The algae species is Chlorella vulgaris, which comes from the freshwater algae species bank of the Institute of Hydrobiology, Chinese Academy of Sciences, and is numbered 29. The inoculation density of the microalgae species is 0.3g / L calculated on a dry basis; adjust the motor speed of the stirring paddle so that the flow rate of the culture medium is between 50cm / s-60cm / s; start the delivery pump in the ammonia water adding device to add ammonia water to the algae liquid to maintain NH4 + The concentration is 4mmol / L; the pH sensor in this embodiment is a commercially available pH electrode, and the probe is inserted below the surface of the microalgae culture liquid. According to the pH value of the culture medium detected by the pH sensor, the pH value is controlled to be 7.8. When the pH value is higher than 7.8, the valve on the carbon dioxide aeration pipe on the carbon replenishment device is opened to replenish carbon dioxide into the algae liquid; when it is lower than 7.8, the carbon replenishment device is closed to detect the cell concentration of the microalgae. When the cell concentration of the microalgae is detected for two consecutive days without change, the microalgae is harvested.

[0028] In this example, after 6 days of cultivation, the yield of algal cells per unit area was calculated to be 11.5 g / (m 2) / d, and through material balance calculation, it is calculated that the utilization rate of CO2 is 80%, and the total power consumption of the stirring paddle is 30 kWh.

[0029] The difference between the comparative example of this embodiment and the embodiment 1 is that the nitrogen source in the culture medium is the traditional sodium nitrate, the carbon replenishment trap depth of the carbon replenishment device is 60cm, and the other conditions are the same. After 6 days of cultivation, the yield of algae cells per unit area in the comparative example is 9.3 g / (m 2 ) / d, it is calculated that the utilization rate of CO2 is 66%, and the total power consumption of the stirring paddle is 45 kWh.

[0030] Embodiment 2:

[0031] The difference between the raceway pool photobioreactor of this embodiment and embodiment 1 is that the carbon replenishing structure adopted is a horizontal immersion carbon replenishing device, and the specific structure of the horizontal immersion carbon replenishing device is referred to embodiment 1 in CN201210138845.8. The use method of this embodiment is the same as that of embodiment 1.

[0032] After 6 days of cultivation, the yield of algae cells per unit area was calculated to be 11.8 g / (m 2 ) / d, and the utilization rate of CO2 is 87% after material balance.

[0033] The comparative example of this embodiment 2 uses the same raceway pool photobioreactor as that of embodiment 2 and adopts the same culture conditions. The difference between the two is that the culture medium uses traditional sodium nitrate as the nitrogen source. After 6 days of culture, the yield of algal cells per unit area is 9.0 g / (m 2 ) / d, and the calculation shows that the utilization rate of CO2 is 60%.

[0034] Obviously, by adopting the technical solution of the present invention, the operation is simpler, the utilization rate of carbon dioxide is significantly increased, and the energy consumption is significantly reduced.

[0035] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A raceway pool photobioreactor for promoting carbon source absorption by ammonia nitrate, characterized in that: The invention comprises a raceway pool body (1), a partition wall (2) arranged in the raceway pool body (1), a pH sensor (5), a stirring paddle (3), a carbon replenishing device (4) for adjusting the pH value of algae liquid, and an ammonia water replenishing device for replenishing ammonia water; the stirring paddle (3) is installed in the raceway pool body (1) and is used to push the algae liquid to flow in a circular manner along the raceway pool body (1); the partition wall (2) isolates the raceway pool body (1) into a circular channel; the pH sensor (5) is located between the carbon replenishing device (4) and the ammonia water replenishing device; the ammonia water replenishing device is located upstream of the carbon replenishing device (4); The ammonia water replenishing device comprises an ammonia water storage tank (8), a delivery pump (7), and a delivery main pipe (6) arranged in the runway pool body (1); the ammonia water storage tank (8) and the delivery pump (7) are both arranged outside the runway pool body (1); the inlet of the delivery pump (7) is connected to the ammonia water storage tank (8) through a pipeline, and the outlet of the delivery pump (7) is connected to the delivery main pipe (6); the delivery main pipe (6) is immersed in the algae liquid, and a plurality of nozzles (9) are arranged on the delivery main pipe (6); The carbon replenishing device (4) is a trap-type carbon replenishing device (41) or a horizontal immersion-type carbon replenishing device (42).

2. A raceway pool photobioreactor for promoting carbon source absorption by ammonia nitrate as claimed in claim 1, characterized in that: The nozzle (9) is arranged toward the carbon replenishing device (4).

3. A method for using the raceway pool photobioreactor for promoting carbon source absorption by ammonia nitrate as claimed in claim 1, characterized in that: a. Add culture medium into the reactor and sterilize it, wherein the depth of the culture medium is 5 cm to 30 cm; the culture medium is one of Zarrouk culture medium, F / 2 culture medium, SM culture medium, D1 culture medium and BG11 culture medium without adding nitrogen source; b. Start the stirring paddle (3) to stir the culture medium evenly, and inoculate the microalgae species into the culture medium, wherein the inoculation density of the microalgae species is between 0.01 g / L and 0.5 g / L calculated on a dry basis; adjust the rotation speed of the stirring paddle (3) so that the flow rate of the culture medium is between 10 cm / s and 100 cm / s; c. Start the delivery pump (7) in the ammonia water adding device to add ammonia water to the algae liquid to maintain the NH 4+ The concentration is 2mmol / L to 4mmol / L; d. According to the pH value of the culture medium detected by the pH sensor (5), when the pH value is higher than the pH value required for microalgae culture, the carbon supplement device (4) is turned on to supplement carbon dioxide into the algae liquid; when the pH value is lower than the pH value required for microalgae culture, the carbon supplement device (4) is turned off; e. Detect the cell concentration of the microalgae, and harvest the microalgae when the cell concentration of the microalgae does not change for two consecutive days.

4. The method for using the raceway pool photobioreactor for promoting carbon source absorption by ammonia nitrate as claimed in claim 3, characterized in that: The disinfection medium used when disinfecting the culture medium is one of ultraviolet rays, sodium hypochlorite and ozone.

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