Microalgae polyculture method for adjusting organic carbon source supply through dissolved oxygen content feedback and application

Abstract

The invention discloses a microalgae polyculture method for adjusting supply of an organic carbon source through dissolved oxygen content feedback and application, and belongs to the technical field of microalgae culture, the method comprises the following steps: an autotrophic stage: introducing air into a culture reactor, and enabling cells to reach a certain concentration through autotrophic growth; in the polyculture stage, ventilation is stopped, dissolved oxygen is monitored in real time, starting and stopping of an organic carbon source pump are dynamically adjusted, and mixed nutrition is achieved; and continuous production: setting a dilution rate, continuously harvesting, supplementing the culture medium, and continuously operating. The addition of an organic carbon source is accurately controlled through the concentration feedback of dissolved oxygen, the photosynthetic and heterotrophic metabolism rates are matched, no net oxygen production (stable DO) is ensured, oxygen self-balance in the system is realized, and finally, the conversion rate of carbon is greatly increased and can reach 0.85 or above. According to the method, the microalgae productivity is remarkably improved under the condition of no gas exchange, and a new thought is provided for large-scale culture with low energy consumption and high carbon efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microalgae cultivation, and particularly relates to a microalgae mixed culture method for regulating organic carbon source supply through dissolved oxygen content feedback and application. BACKGROUND

[0002] Traditional microalgae culture modes: 1) Autotrophy: under light conditions, CO2 is used as a carbon source to accumulate biomass, and O2 is released at the same time; 2) Heterotrophy: under dark conditions, O2 is used, and organic carbon sources (acetic acid, glucose, glycerol, etc.) are used as carbon sources to accumulate biomass, and CO2 is released at the same time; 3) Mixed culture (complementary culture): 1) and 2) are combined, but the addition of organic carbon sources is usually batch, such as adding 20 g / L of glucose, etc. for cultivation, and high-intensity stirring (or aeration) is accompanied to supplement the oxygen content. The disadvantage of this method is that the carbon conversion rate (c / c mol ratio: i.e. the number of moles of organic carbon that can be converted into biomass carbon per mole) can only reach about 0.5. SUMMARY

[0003] The purpose of the present application is to solve the problems of the prior art, and to provide a microalgae mixed culture method for regulating organic carbon source supply through dissolved oxygen content feedback and application. The addition of organic carbon sources is precisely controlled through the concentration of dissolved oxygen, the photosynthesis and heterotrophic metabolism rates are matched, net oxygen production is ensured (DO is stable), oxygen self-balancing in the system is achieved, and ultimately the carbon conversion rate is greatly improved, which can reach more than 0.85. The present application significantly improves the microalgae productivity under the condition of no gas exchange, and provides a new idea for low-energy and high-carbon-efficiency large-scale cultivation.

[0004] The present application is realized by the following technical solutions: The microalgae mixed culture method for regulating organic carbon source supply through dissolved oxygen content feedback comprises the following steps: Step one, autotrophic phase: aeration is performed in the cultivation reactor, and cells are grown by autotrophy to a certain concentration; Step two, mixed culture phase: stop aeration, real-time monitor dissolved oxygen and dynamically adjust the start and stop of the organic carbon source pump to realize mixed nutrition; Step three, continuous production: set the dilution rate, continuously harvest and supplement the culture medium, and continuously run.

[0005] Preferably, in the step one, the CO2 content in the aeration is 1-5%; and the aeration amount is 0.1-0.3 vvm.

[0006] Preferably, in the step one, when growing by autotrophy: the stirring speed at the bottom of the cultivation reactor is 50-200 rpm; and an LED light source is built-in in the cultivation reactor, so that the light intensity in the cultivation reactor is 200-500 μmol•m⁻²•s⁻¹.

[0007] Preferably, the cell concentration in step one reaches 1-3 g / L.

[0008] Preferably, in step two, the pump speed of the organic carbon source is dynamically adjusted: when the dissolved oxygen is 90-130%, the organic carbon source pump stops running; when the dissolved oxygen is lower than 90%, the organic carbon source pump stops running; when the dissolved oxygen is higher than 130%, the organic carbon source pump starts.

[0009] Preferably, in step two, when mixed nutrition, the stirring speed is adjusted to 100-300 rpm.

[0010] Preferably, in step three, the dilution rate is set to 0.2-2 day⁻¹; and the continuous operation is more than 30 days.

[0011] Preferably, the organic carbon source is acetic acid, glucose or glycerol.

[0012] The microalgae mixed culture method for adjusting the supply of organic carbon source by dissolved oxygen content feedback is applied to Chlorella and sulfur red algae.

[0013] Compared with the prior art, the present application has the following advantages and beneficial effects: 1. The microalgae mixed culture method for adjusting the supply of organic carbon source by dissolved oxygen content feedback provided by the present application can improve the biomass concentration to 4-10 g / L (2-3 times of autotrophic), and the carbon conversion rate is ≥0.85 (the ratio of the moles of organic carbon to the moles of microalgae).

[0014] 2. The microalgae mixed culture method for adjusting the supply of organic carbon source by dissolved oxygen content feedback provided by the present application is applied to the cultivation of Chlorella and sulfur red algae.

[0015] 3. The culture scheme provided by the present application realizes intelligent regulation and control of the culture process, significantly reduces energy consumption and labor cost, adjusts the supply of organic carbon source by real-time feedback of dissolved oxygen content, avoids the waste or inhibition phenomenon caused by traditional batch addition, makes the whole mixed culture process efficient and stable, and lays a foundation for industrialized continuous production.

[0016] 4. The culture scheme provided by the present application effectively solves the problem of oxygen accumulation in mixed culture, creates a stable growth environment, matches the photosynthetic and heterotrophic metabolic rates, ensures that there is no net oxygen accumulation in the system (DO is stable), avoids the stress effect of high dissolved oxygen on microalgae growth, and significantly improves the biomass yield and carbon conversion efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The flowchart of the present application. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0019] Example 1 like Figure 1 As shown, this embodiment provides a method for microalgae polyculture by adjusting the organic carbon source supply through dissolved oxygen content feedback, including the following steps: 1) Autotrophic stage: Chlorella was cultured in a 100L tank reactor. 2% CO2 was introduced into the tank at a ventilation rate of 0.3 vvm. The bottom agitator rotated at 80 rpm. Light supply was provided by a 300W built-in LED light source. The inoculum concentration was 0.3 g / L. After 5 days of culture, the cell concentration reached 1.8 g / L, and dissolved oxygen (DO) reached 120%.

[0020] 2) Co-culture stage: Stop aeration, adjust the stirring speed to 150 rpm, add 10% w / w acetic acid solution, monitor DO in real time using LabVIEW software and dynamically adjust the acetic acid pump speed. When DO reaches 110%, stop adding acetic acid, and then restart adding acetic acid when DO rises to 130%. This feedback control mechanism achieves efficient utilization of organic carbon.

[0021] 3) Continuous production phase: Harvest and add new culture medium at a dilution rate of 0.5 / day, and continue operation for 50 days; 4) Final harvest: All were harvested, and the conversion rate of organic carbon (c / c mol ratio) was measured to be 0.87.

[0022] Example 2 like Figure 1 As shown, this embodiment provides a method for microalgae polyculture by adjusting the organic carbon source supply through dissolved oxygen content feedback, including the following steps: 1) Autotrophic stage: Chlorella was cultured in an 800L tank reactor. 2% CO2 was introduced into the tank at a flow rate of 0.3 vvm. The bottom agitator rotated at 100 rpm, and a 1000W external LED light source was used for energy supply. The inoculum concentration was 0.1 g / L. After 5 days of culture, the cell concentration reached 1 g / L, and dissolved oxygen (DO) reached 105%.

[0023] 2) Co-culture stage: Aeration is stopped, the stirring speed is adjusted to 200 rpm, and a 15% w / w glucose solution is added. The glucose pump speed is dynamically adjusted by real-time monitoring of dissolved oxygen (DO). When the DO reaches 95%, acetic acid addition is stopped. Then, when the DO rises to 115%, glucose addition is restarted. This feedback control mechanism achieves efficient utilization of organic carbon.

[0024] 3) Continuous production phase: Harvest and add new culture medium at a dilution rate of 0.2 g / day, and continue operation for 30 days; 4) Final harvest: All harvest, measured organic carbon conversion rate (c / c mol ratio) is 0.93.

[0025] Example 3 As Figure 1 shown, the present embodiment provides a microalgae mixed culture method for feedback regulation of organic carbon source supply by dissolved oxygen content, comprising the following steps: 1) Autotrophic phase: Cultivate sulfur red algae, the cultivation reactor is a 1000L tank reactor, 2% CO2 is introduced into the tank, the aeration rate is 0.3vvm, the bottom stirring speed is 100rpm, the light energy supply is 3000w LED built-in light source, and the inoculation concentration is 0.5g / L. Cultivate for 5 days, the cell concentration reaches 2.4 g / L, and the dissolved oxygen (DO) reaches 130%; 2) Mixed culture phase: Stop aeration, adjust the stirring speed to 200rpm, add glycerol, monitor DO in real time and dynamically adjust the glycerol pump speed, when DO reaches 125%, stop glycerol addition, then when DO rises to 135%, start glycerol addition again. Through the above feedback control mechanism, efficient utilization of organic carbon is realized.

[0026] 3) Continuous production phase: Harvest and add new medium at a dilution rate of 1.2 / day, continue to run for 60 days; 4) Final harvest: All harvest, measured organic carbon conversion rate (c / c mol ratio) is 0.95.

[0027] Example 4 A microalgae mixed culture method for feedback regulation of organic carbon source supply by dissolved oxygen content, comprising the following steps: Step one, autotrophic phase: aeration in the cultivation reactor, autotrophic growth, and the cell concentration reaches a certain concentration; Step two, mixed culture phase: stop aeration, monitor dissolved oxygen in real time and dynamically adjust the start and stop of the organic carbon source pump to realize mixed nutrition; Step three, continuous production: set the dilution rate, continuously harvest and replenish the medium, and continuously run.

[0028] In step one, the content of CO2 in aeration is 1%; the aeration rate is 0.1vvm.

[0029] In step one, when autotrophic growth: the bottom stirring speed of the cultivation reactor is 50rpm; the cultivation reactor is provided with LED light source, so that the light intensity in the cultivation reactor is 200μmol•m⁻²•s⁻¹.

[0030] In step one, the cell concentration reaches 1g / L.

[0031] The pump speed of the organic carbon source is dynamically adjusted in the second step: the organic carbon source pump stops running when the dissolved oxygen is 90-130%; the organic carbon source pump stops running when the dissolved oxygen is lower than 90%; and the organic carbon source pump starts running when the dissolved oxygen is higher than 130%.

[0032] In the second step, the stirring speed is adjusted to 100 rpm when mixed nutrition.

[0033] In the third step, the dilution rate is set to 0.2 day-1; and the continuous operation lasts for 30 days.

[0034] The organic carbon source is acetic acid. The conversion rate (c / c mol ratio) of organic carbon is 0.87.

[0035] The microalgae mixed culture method for adjusting the supply of organic carbon source by dissolved oxygen content feedback is applied to Chlorella.

[0036] Example 5 The microalgae mixed culture method for adjusting the supply of organic carbon source by dissolved oxygen content feedback comprises the following steps: Step 1, autotrophic phase: aeration is carried out in the cultivation reactor, and cells grow by autotrophy to a certain concentration; Step 2, mixed nutrition phase: stop aeration, real-time monitor dissolved oxygen and dynamically adjust the start and stop of the organic carbon source pump to realize mixed nutrition; Step 3, continuous production: set the dilution rate, continuously harvest and supplement the medium, and continuously operate.

[0037] In the first step, the content of CO2 in aeration is 5%; and the aeration amount is 0.2 vvm.

[0038] In the first step, when autotrophic growth: the stirring speed at the bottom of the cultivation reactor is 200 rpm; and the cultivation reactor is provided with an LED light source, so that the light intensity in the cultivation reactor is 500 μmol•m⁻²•s⁻¹.

[0039] In the first step, the cell concentration reaches 3 g / L.

[0040] The pump speed of the organic carbon source is dynamically adjusted in the second step: the organic carbon source pump stops running when the dissolved oxygen is 90-130%; the organic carbon source pump stops running when the dissolved oxygen is lower than 90%; and the organic carbon source pump starts running when the dissolved oxygen is higher than 130%.

[0041] In the second step, the stirring speed is adjusted to 300 rpm when mixed nutrition.

[0042] In the third step, the dilution rate is set to 2 day-1; and the continuous operation lasts for 50 days.

[0043] The organic carbon source is acetic acid. The conversion rate of organic carbon (c / c mol ratio) is 0.86.

[0044] The microalgae mixed culture method of feeding back and adjusting the organic carbon source by the dissolved oxygen content is applied to the sulfur red algae.

[0045] Comparative Example 1 The difference between this comparative example and Example 4 is that the CO2 content in the ventilation in Step One is 0.5%. The conversion rate of organic carbon (c / c mol ratio) is 0.67.

[0046] Comparative Example 2 The difference between this comparative example and Example 5 is that the CO2 content in the ventilation in Step One is 6%. The conversion rate of organic carbon (c / c mol ratio) is 0.71.

[0047] Comparative Example 3 The difference between this comparative example and Example 4 is that the ventilation amount in Step One is 0.05 vvm. The conversion rate of organic carbon (c / c mol ratio) is 0.52.

[0048] Comparative Example 4 The difference between this comparative example and Example 4 is that the cell concentration reaches 0.5 g / L in Step One. The conversion rate of organic carbon (c / c mol ratio) is 0.55.

[0049] Comparative Example 5 The difference between this comparative example and Example 4 is that the dilution rate is set to 0.1 day⁻¹ in Step Three. The conversion rate of organic carbon (c / c mol ratio) is 0.56.

[0050] Comparative Example 6 The difference between this comparative example and Example 5 is that the dilution rate is set to 2.5 day⁻¹ in Step Three. The conversion rate of organic carbon (c / c mol ratio) is 0.64.

[0051] Comparative Example 7 The difference between this comparative example and Example 4 is that the pump speed of the organic carbon source is dynamically adjusted in Step Two: when the dissolved oxygen is 80-130%, the organic carbon source pump stops running; when the dissolved oxygen is lower than 80%, the organic carbon source pump stops running; when the dissolved oxygen is higher than 130%, the organic carbon source pump starts. The conversion rate of organic carbon (c / c mol ratio) is 0.65.

[0052] Comparative Example 8 The difference between the present comparative example and Example 5 is that in the second step, the pump speed of the organic carbon source is dynamically adjusted: when the dissolved oxygen is 90-140%, the pump of the organic carbon source stops running; when the dissolved oxygen is lower than 90%, the pump of the organic carbon source stops running; and when the dissolved oxygen is higher than 140%, the pump of the organic carbon source starts running. The conversion rate of the organic carbon (c / c mol ratio) is measured to be 0.61.

[0053] Comparative Example 9 The difference between the present comparative example and Example 4 is that in the second step, the pump speed of the organic carbon source is dynamically adjusted: when the dissolved oxygen is 90-120%, the pump of the organic carbon source stops running; when the dissolved oxygen is lower than 90%, the pump of the organic carbon source stops running; and when the dissolved oxygen is higher than 120%, the pump of the organic carbon source starts running. The conversion rate of the organic carbon (c / c mol ratio) is measured to be 0.62.

[0054] Comparative Example 10 The difference between the present comparative example and Example 5 is that in the second step, the pump speed of the organic carbon source is dynamically adjusted: when the dissolved oxygen is 80-140%, the pump of the organic carbon source stops running; when the dissolved oxygen is lower than 80%, the pump of the organic carbon source stops running; and when the dissolved oxygen is higher than 140%, the pump of the organic carbon source starts running. The conversion rate of the organic carbon (c / c mol ratio) is measured to be 0.1.57.

[0055] The above description is only the preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification or equivalent change based on the technical essence of the present application to the above embodiment falls within the protection scope of the present application.

Claims

1. A method for the co-culture of microalgae with an organic carbon source supply regulated by feedback on the dissolved oxygen content, characterized in that, The method comprises the following steps: Step one, autotrophic phase: aeration is conducted in the cultivation reactor, and cells grow by autotrophy to a certain concentration; Step two, mixed culture phase: aeration is stopped, dissolved oxygen is monitored in real time, and the start and stop of the organic carbon source pump are dynamically adjusted to realize mixed nutrition; Step three, continuous production: the dilution rate is set, the medium is continuously supplemented and harvested, and the operation is continuously carried out.

2. The method according to claim 1, wherein the microalgae polyculture method is characterized by: In step one, the content of CO2 in aeration is 1-5%, and the aeration amount is 0.1-0.3vvm.

3. The method according to claim 1, wherein the microalgae polyculture method is characterized by: In step one, when autotrophic growth: the stirring speed at the bottom of the cultivation reactor is 50-200rpm; the cultivation reactor is provided with an internal LED light source, so that the light intensity in the cultivation reactor is 200-500 μmol•m⁻²•s⁻¹.

4. The method according to claim 1, wherein the microalgae polyculture method is characterized by: In step one, the cell concentration reaches 1-3g / L.

5. The method according to claim 1, wherein the microalgae polyculture method is characterized by: In step two, the pump speed of the organic carbon source is dynamically adjusted: when the dissolved oxygen is 90-130%, the organic carbon source pump remains in the original state; when the dissolved oxygen is lower than 90%, the organic carbon source pump stops running; when the dissolved oxygen is higher than 130%, the organic carbon source pump starts.

6. The method for microalgae polyculture by feedback adjustment of organic carbon source supply according to the dissolved oxygen content of claim 1, characterized in that: In step two, when mixed nutrition: the stirring speed is adjusted to 100-300rpm.

7. The method according to claim 1, wherein the microalgae polyculture method is characterized by: In step three, the dilution rate is set to 0.2-2 day⁻¹; the operation is continuously carried out for more than 30 days.

8. The method for microalgae polyculture by feedback adjustment of organic carbon source supply according to the dissolved oxygen content of claim 1, characterized in that: The organic carbon source is acetic acid, glucose or glycerol.

9. The microalgal mixed culture method for adjusting the supply of organic carbon source by dissolved oxygen content feedback according to any one of claims 1-8 is applied to Chlorella and Rhodothamnus.

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