Microalgae culture method
By using a flash light source and a culture medium with a specific composition, the problem of low light energy utilization in traditional microalgae cultivation has been solved, thereby improving the efficiency of microalgae biomass production and enhancing economic benefits.
Patent Information
- Application Number
- CN202410256535.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-03-06
- Publication Date
- 2025-09-09
AI Technical Summary
Traditional microalgae cultivation uses natural light with low energy density, resulting in slow microalgae growth, low light energy utilization, and high power consumption.
Microalgae were cultured using a flash light source. The duration of each emission was 0.1–2.0 ms, and the duration of non-emission was 0.2–4.5 ms. The wavelength was 380–780 nm, the color temperature was 4000–7000 K, and the surface light intensity was 5000–50000 lx. The culture medium contained phosphorus-containing wastewater, carbon source, nitrogen source, iron source, magnesium source, and pH adjuster. The suitable pH value was 8–11.
It effectively reduces the power consumption per unit of microalgae biomass for light, improves light energy utilization and microalgae biomass production efficiency, and has good economic benefits.
Smart Images
Figure BDA0004729413500000101
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of microalgae biotechnology, and in particular, to a microalgae cultivation method. Background Art
[0002] Microalgae are single-celled organisms capable of photosynthesis, converting inorganic carbon, nitrogen, and phosphorus into biomass with exceptionally high efficiency, making them highly valuable for future applications. Traditional microalgae cultivation utilizes open-type culture devices, relying on natural light as the energy source for growth. This method is simple and low-cost, but due to the low energy density of natural light, microalgae growth is slow.
[0003] With the development of semiconductor technology, light-emitting diodes (LEDs) are becoming increasingly popular as a new type of electric light source. LEDs offer a range of advantages, including low energy consumption, high brightness, and adjustable wavelength and color temperature. While the use of LEDs as a light source for plant and microalgae growth has been reported, these technologies still suffer from limitations such as slow microalgae biomass accumulation, high power consumption, and low light energy utilization. Summary of the Invention
[0004] The present invention aims to provide a microalgae cultivation method to improve the light energy utilization rate and microalgae biomass production efficiency during the microalgae growth process.
[0005] In order to achieve the above objectives, the present disclosure provides a microalgae cultivation method, which comprises:
[0006] The microalgae species are cultured in the presence of a culture solution, wherein the culture light source is a flash light source, each light emission duration of the flash light source is 0.1 to 2.0 ms, and the non-light emission duration is 0.2 to 4.5 ms.
[0007] Optionally, each lighting duration of the flash light source is 0.2 to 0.75 ms, and each non-lighting duration is 0.25 to 1.5 ms.
[0008] Optionally, the wavelength of the flash light source is 380-780 nm, the color temperature is 4000-7000 K, and the surface illumination intensity is 5000-50000 lx;
[0009] Optionally, the color temperature of the flash light source is 5000-6500K.
[0010] Optionally, the culture solution contains phosphorus-containing wastewater, a carbon source, a nitrogen source, an iron source, a magnesium source, optional trace elements and an optional pH regulator;
[0011] The phosphorus-containing wastewater contains at least one of phosphoric acid molecules, hydrogen phosphate ions, dihydrogen phosphate ions and phosphate ions; and the pH value of the culture solution is 8-11.
[0012] Optionally, in the phosphorus-containing wastewater, the total phosphorus content calculated as phosphorus element is 10 to 5000 mg / L; the phosphorus element in the form of phosphoric acid molecules, hydrogen phosphate ions, dihydrogen phosphate ions and / or phosphate ions accounts for 10 to 100% of the total phosphorus element;
[0013] In the culture medium, PO4 3- The calculated phosphate ion content is 5 to 3000 mg / L.
[0014] Optionally, based on the total weight of the culture solution, the content of the wastewater is 0.5-100 weight%, the content of the carbon source is 0.1-3 weight%, the content of the nitrogen source is 0.05-0.5 weight%, the content of the iron source is 0.0002-0.005 weight%, the content of the magnesium source is 0.005-0.05 weight%, the content of the trace elements is 0-0.001 weight%, and the content of the pH regulator is 0-0.001 weight%.
[0015] Optionally, the weight ratio of the microalgae species to the phosphorus-containing wastewater is 1:(0.01-10).
[0016] Optionally, the culture conditions include: ventilation volume of 0.1 to 5 m 3 / min, temperature is 20-35℃, and ventilation time is 1-24h / day.
[0017] Optionally, the microalgae species is at least one selected from Spirulina species, Chlorella species, Monopterus species and Scenedesmus species.
[0018] Through the above technical solution, the present disclosure adopts a flash light source as a light source for cultivating microalgae, which can effectively reduce the lighting power consumption per unit of microalgae biomass produced, improve the light energy utilization rate and microalgae biomass production efficiency, and has good economic benefits.
[0019] Other features and advantages of the present disclosure will be described in detail in the following detailed description. DETAILED DESCRIPTION
[0020] The following describes the specific embodiments of the present disclosure in detail. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.
[0021] The present disclosure provides a microalgae cultivation method, which includes: cultivating microalgae species in the presence of a culture solution, wherein the culture light source is a flash light source, and each light emission duration of the flash light source is 0.1 to 2.0 ms, and the non-light emission duration is 0.2 to 4.5 ms.
[0022] The flash light source refers to a light source that rapidly alternates between emitting and not emitting light (i.e., alternating between light and dark). Specifically, in the present disclosure, the microalgae species are cultured under a light source that alternates between emitting light for 0.1 to 2.0 milliseconds and not emitting light for 0.2 to 4.5 milliseconds. Shortening the duration of each flash light source's illumination and non-illumination periods helps reduce photodamage to the microalgae cells and reduces light energy wasted due to incomplete absorption. Furthermore, shortening the illumination duration can reduce energy losses caused by photorespiration, further improving light energy utilization.
[0023] In a preferred embodiment, the duration of each light emission of the flash light source is 0.2 to 0.75 ms, and the duration of non-light emission is 0.25 to 1.5 ms. The duration of each light emission of the flash light source can be the same as or different from the duration of non-light emission. For example, the duration of each light emission and the duration of non-light emission are both 0.5 ms; or, the duration of each light emission is 0.25 ms and the duration of non-light emission is 0.75 ms; or, the duration of each light emission is 0.5 ms and the duration of non-light emission is 1.0 ms. Further preferably, the duration of each light emission of the flash light source is different from the duration of non-light emission, and the ratio of the duration of each light emission to the duration of non-light emission is 1:(1.5 to 2.5).
[0024] Furthermore, the flashlight source is preferably an artificial light source. It can be a continuous spectrum light source consisting of a specific wavelength range. Specifically, the flashlight source can have a wavelength of 380 to 780 nm, a color temperature of 4000 to 7000 K, preferably 5000 to 6500 K, and a surface illumination intensity of 5000 to 50000 lx. This facilitates the absorption of photosensitive pigments in microalgae cells of photons within a specific wavelength range, converting light energy into chemical energy, and increasing the rate of biomass accumulation.
[0025] According to the present disclosure, the culture medium can be various culture media suitable for the growth of microalgae, and its components generally include various nutrients required for the growth of microalgae (such as carbon source, nitrogen source, phosphorus source, etc.), which can be commercially available products or prepared in the laboratory.
[0026] In a specific embodiment of the present disclosure, the culture solution contains phosphorus-containing wastewater, a carbon source, a nitrogen source, an iron source, a magnesium source, optional trace elements, and an optional pH adjuster; wherein the phosphorus-containing wastewater contains at least one of phosphate molecules, hydrogen phosphate ions, dihydrogen phosphate ions, and phosphate ions. The phosphorus-containing wastewater can provide the phosphorus source required for microalgae growth, thereby consuming the phosphate ions in the phosphorus-containing wastewater through microalgae cultivation, thereby achieving the purpose of microalgae treatment (conversion) of the phosphorus-containing wastewater. Furthermore, this method can reduce the amount of light power consumed per unit of phosphorus absorption while simultaneously obtaining a high yield of microalgae biomass, resulting in excellent economic, ecological, and social benefits.
[0027] There is no special restriction on the source of the phosphorus-containing wastewater, which can be specifically wastewater containing phosphate ions discharged from various industries. In particular, the microalgae cultivation method disclosed in the present invention is particularly suitable for treating phosphorus-containing wastewater with a high phosphorus content. Specifically, the total phosphorus content in the phosphorus-containing wastewater in terms of phosphorus element can be 10 to 5000 mg / L, preferably 50 to 2000 mg / L; the proportion of phosphorus elements in the form of phosphoric acid molecules, hydrogen phosphate ions, dihydrogen phosphate ions and / or phosphate ions in the total phosphorus element can be 10 to 100%, preferably 50 to 100%. Among them, the determination method of total phosphorus content (TP) and phosphate ion content can refer to the standard method HJ 670-2013. In a specific embodiment, the introduction of the phosphorus-containing wastewater causes the culture solution to contain PO4 3- The calculated phosphate ion content can be 5 to 3000 mg / L, preferably 200 to 2000 mg / L, and more preferably 500 to 1000 mg / L. When the phosphate ion concentration is higher than the concentration required for microalgae culture, water can be added to dilute it appropriately.
[0028] In this embodiment, the culture solution can be obtained by mixing phosphorus-containing wastewater with a carbon source, a nitrogen source, an iron source, a magnesium source, optional trace elements and an optional pH regulator, wherein the content of each component can be adjusted within a certain range. Specifically, based on the total weight of the culture solution, the content of the phosphorus-containing wastewater can be 0.5-100 weight%, the content of the carbon source can be 0.1-3 weight%, the content of the nitrogen source can be 0.05-0.5 weight%, the content of the iron source can be 0.0002-0.005 weight%, the content of the magnesium source can be 0.005-0.05 weight%, the content of the trace elements can be 0-0.001 weight%, and the content of the pH regulator can be 0-0.001 weight%. The composition of the above components can be selected based on the type of microalgae. The content of the carbon source, nitrogen source, iron source, magnesium source, and trace elements can be adjusted based on various common microalgae culture media (such as BG-11 medium, SE medium, Pr medium, f / 2 medium, and Zarrouk medium). Examples of the carbon source include sodium bicarbonate and sodium carbonate; examples of the nitrogen source include sodium nitrate and urea; examples of the iron source include ferrous sulfate, ferrous chloride, and ferric chloride; examples of the magnesium source include magnesium sulfate and magnesium chloride; and examples of the trace elements include boric acid and manganese chloride. Furthermore, the pH of the culture medium can be between 8 and 11, preferably between 8.5 and 10.5. By adjusting the pH of the culture medium to within the above range, the phosphorus therein can be present as phosphate ions, which can be utilized by the microalgae. If the pH of the culture medium is outside the above range, it can be adjusted by adding a pH adjuster, such as nitric acid, sodium bicarbonate, and CO2.
[0029] The amount of the culture solution can be adjusted as needed. In order to achieve a better treatment effect of phosphorus-containing wastewater, the weight ratio of the microalgae species to the phosphorus-containing wastewater can be 1:(0.01-10), preferably 1:(0.1-5).
[0030] In this embodiment, the culturing may be performed in a wastewater treatment device containing the phosphorus-containing wastewater, wherein the flash light source is provided in the wastewater treatment device.
[0031] According to the present disclosure, the culture conditions may include: ventilation volume of 0.1 to 5 m 3 / min, temperature is 20-35℃, and ventilation time is 1-24h / day.
[0032] The method disclosed herein is applicable to various common microalgae species. In particular, the microalgae species may be microalgae species that can use phosphate ions in wastewater as a phosphorus source, for example, eukaryotic algae species and / or prokaryotic algae species, preferably prokaryotic algae species. In one embodiment, the microalgae species may be at least one selected from Chlorella (such as Chlorella vulgaris, C. ellipsoidea or C. pyrenoidosa), Monoraphidium (such as Monoraphidium dybowskii), Scenedesmus (such as Scenedesmus obliqnus, S. acuminatus, S. arcuatus, S. armatus or S. quadricauda), and Spirulina (such as Spirulina platensis or Spirulina maxima). Preferably, the microalgae species is a Spirulina species.
[0033] The technical solution disclosed herein is simple and easy to implement, and can effectively reduce the lighting power consumption per unit of microalgae biomass production, thereby improving light energy utilization and microalgae biomass production efficiency. The produced microalgae biomass can be applied in the fields of feed, health products, materials, etc. after post-processing, and has high economic value.
[0034] The present disclosure is further described in detail below with reference to the embodiments, but they do not limit the present disclosure.
[0035] The microalgae species used in the following examples and comparative examples are Spirulina platensis species numbered FACHB-314 and Chlorella vulgaris species numbered FACHB-2338 purchased from the Freshwater Algae Seed Bank of the Chinese Academy of Sciences.
[0036] Phosphorus-containing wastewater comes from the caprolactam production process. Its total phosphorus content is 462.5 mg / L. The phosphorus element present in phosphate ions accounts for 94.3% of the total phosphorus element. The composition is: NO3 - 4.24g / L, SO4 2- 1.5mg / L, PO4 3- 1336mg / L, Na + 2274mg / L, Ca 2+ 115mg / L, toluene 0.01mg / L, caprolactam 1mg / L.
[0037] Determination of absorbance (OD value) of culture solution: The absorbance value of the culture solution was measured at the maximum absorption peak wavelength (560 nm) using a spectrophotometer with distilled water as a control, as an indicator of microalgae concentration.
[0038] The determination method of phosphate ion refers to HJ 670-2013 Water quality - Determination of phosphate and total phosphorus - Continuous flow-ammonium molybdate spectrophotometry.
[0039] Microalgae biomass accumulation rate = (biomass dry weight of culture medium after culture completion - initial biomass dry weight of culture medium) / (culture volume × culture days).
[0040] Lighting power consumption per unit microalgae biomass = light source input power × culture days × 24 / (biomass dry weight of culture medium after the completion of culture - initial biomass dry weight of culture medium).
[0041] Light consumption per unit phosphorus absorption = light source input power × culture days × 24 × 3.06 / [(initial PO4 3- Concentration - PO4 of the culture medium after the culture is completed 3- concentration) × culture volume].
[0042] Example 1
[0043] Zarrouk medium (without adding phosphate) was introduced into a culture tank (with a size of 0.4 m×0.6 m), Spirulina algae species were inoculated, and phosphorus-containing wastewater to be treated was introduced to obtain a culture solution. The pH value of the culture solution is 9.80. Based on the total weight of the culture solution, the content of phosphorus-containing wastewater is 46.8% by weight, the content of carbon source sodium bicarbonate is 0.84% by weight, the content of nitrogen source NaNO3 is 0.25% by weight, the content of iron source FeSO4·7H2O is 0.001% by weight, the content of magnesium source MgSO4·7H2O is 0.02% by weight, the content of trace element H3BO3 is 0.000286% by weight, the content of trace element (NH4)2MoO4 is 0.000002% by weight, the content of trace element MnCl·4H2O is 0.00018% by weight, the content of trace element CuSO4·5H2O is 0.000008% by weight, the content of trace element ZnSO4·7H2O is 0.000022% by weight, the content of pH regulator NaOH is 0-0.001% by weight, and the PO4 3- The concentration is 625 mg / L. The weight ratio of Spirulina to phosphorus-containing wastewater is 1:1.17. The OD of the culture medium after inoculation is 560 The temperature is about 0.3, and the culture depth is 0.4m. Air is introduced into the culture tank through the aeration pipe. At 28℃ and a ventilation volume of 0.2m 3 The culture was carried out under the conditions of 1% HCl / min and 24 h / day ventilation time.
[0044] The culture light source used an LED artificial light source with a light source length of 0.6 m, a light source spacing of 0.1 m, a wavelength of 380-780 nm, a color temperature of 6000 K, and a surface illumination intensity of 20,000 lx. The light source was set to a flashing light source that alternated between emitting and not emitting light, with each emitting light duration of 0.5 ms and each not emitting light duration of 1.0 ms (i.e., a flash frequency of 667 Hz and a duty cycle of 33%). A power detector was used to measure the light source input power.
[0045] The culture time was 15 days. The culture fluid samples were taken on the 0th and 15th days to detect the biomass dry weight and PO4 3- The concentration was used to calculate the microalgae biomass accumulation rate, the power consumption per unit microalgae biomass and phosphorus absorption, and the results are listed in Table 1.
[0046] Example 2
[0047] Microalgae were cultured according to the method of Example 1, except that the color temperature of the flash light source was 5000K.
[0048] Example 3
[0049] Microalgae were cultured according to the method of Example 1, except that the color temperature of the flash light source was 6500K.
[0050] Example 4
[0051] Microalgae were cultured according to the method of Example 1, except that each light emission duration of the flash light source was 0.5 ms, and each non-light emission duration was 0.5 ms (ie, the flash frequency was 1000 Hz, and the duty cycle was 50%).
[0052] Example 5
[0053] Microalgae were cultured according to the method of Example 1, except that the flash light source had a light emission duration of 0.25 ms and a non-light emission duration of 0.5 ms (ie, a flash frequency of 1333 Hz and a duty cycle of 33%).
[0054] Example 6
[0055] Microalgae were cultured according to the method of Example 1, except that the flash light source had a light emission duration of 2.0 ms and a non-light emission duration of 4.5 ms (ie, a flash frequency of 154 Hz and a duty cycle of 31%).
[0056] Example 7
[0057] Microalgae were cultured according to the method of Example 1, except that the flash light source had a light emission duration of 0.1 ms and a non-light emission duration of 0.2 ms (ie, a flash frequency of 3333 Hz and a duty cycle of 33%).
[0058] Example 8
[0059] Microalgae were cultured according to the method of Example 1, except that the color temperature of the flash light source was 4000K.
[0060] Example 9
[0061] Microalgae were cultured according to the method of Example 1, except that the color temperature of the flash light source was 7000K.
[0062] Example 10
[0063] Microalgae were cultured according to the method of Example 1, except that the weight ratio of Spirulina species to phosphorus-containing wastewater was 1:10.
[0064] Example 11
[0065] Microalgae were cultured according to the method of Example 1, except that the Spirulina species was replaced with the Chlorella species.
[0066] Comparative Example 1
[0067] Microalgae were cultured according to the method of Example 1, except that the flash light source had a light emission duration of 50 ms and a non-light emission duration of 50 ms (ie, a flash frequency of 10 Hz and a duty cycle of 50%).
[0068] Comparative Example 2
[0069] Microalgae were cultured according to the method of Example 1, except that the flash light source had a light emission duration of 5 ms and a non-light emission duration of 5 ms (ie, a flash frequency of 1 Hz and a duty cycle of 50%).
[0070] Comparative Example 3
[0071] Microalgae were cultured according to the method of Example 1, except that the flash light source had a light emission duration of 0.005 ms and a non-light emission duration of 0.005 ms (ie, a flash frequency of 100 kHz and a duty cycle of 50%).
[0072] Comparative Example 4
[0073] Wastewater treatment was carried out according to the method of Example 1, except that no flash light source was used, that is, the artificial light source was a continuous light source.
[0074] Table 1
[0075]
[0076] As can be seen from Table 1, the method disclosed herein can effectively reduce the light power consumption per unit of microalgae biomass production, and improve the light energy utilization rate and microalgae biomass production efficiency.
[0077] The preferred embodiments of the present disclosure are described in detail above. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.
[0078] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.
[0079] In addition, the various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.
Claims
1. A microalgae cultivation method, characterized in that: The method includes: The microalgae species are cultured in the presence of a culture solution, wherein the culture light source is a flash light source, each light emission duration of the flash light source is 0.1 to 2.0 ms, and the non-light emission duration is 0.2 to 4.5 ms.
2. The method according to claim 1, wherein The flash light source has a lighting duration of 0.2 to 0.75 ms and a non-lighting duration of 0.25 to 1.5 ms.
3. The method according to claim 1 or 2, wherein: The wavelength of the flash light source is 380-780nm, the color temperature is 4000-7000K, and the surface illumination intensity is 5000-50000lx.
4. The method according to claim 3, wherein: The color temperature of the flash light source is 5000-6500K.
5. The method according to claim 1, wherein The culture solution contains phosphorus-containing wastewater, a carbon source, a nitrogen source, an iron source, a magnesium source, optional trace elements and an optional pH regulator; The phosphorus-containing wastewater contains at least one of phosphoric acid molecules, hydrogen phosphate ions, dihydrogen phosphate ions and phosphate ions; and the pH value of the culture solution is 8-11.
6. The method according to claim 5, wherein: The phosphorus-containing wastewater has a total phosphorus content of 10 to 5000 mg / L in terms of phosphorus element; the phosphorus element in the form of phosphoric acid molecules, hydrogen phosphate ions, dihydrogen phosphate ions and / or phosphate ions accounts for 10 to 100% of the total phosphorus element; In the culture medium, PO4 3- The calculated phosphate ion content is 5 to 3000 mg / L.
7. The method according to claim 5, wherein: Based on the total weight of the culture solution, the content of the phosphorus-containing wastewater is 0.5 to 100 weight%, the content of the carbon source is 0.1 to 3 weight%, the content of the nitrogen source is 0.05 to 0.5 weight%, the content of the iron source is 0.0002 to 0.005 weight%, the content of the magnesium source is 0.005 to 0.05 weight%, the content of the trace elements is 0 to 0.001 weight%, and the content of the pH regulator is 0 to 0.001 weight%.
8. The method according to claim 5, wherein The weight ratio of the microalgae species to the phosphorus-containing wastewater is 1:(0.01-10).
9. The method according to claim 1, wherein The culture conditions include: ventilation volume of 0.1 to 5 m 3 / min, temperature is 20-35℃, and ventilation time is 1-24h / day.
10. The method according to claim 1, wherein The microalgae species is at least one selected from the group consisting of Spirulina species, Chlorella species, Monopterus species and Scenedesmus species.