Microalgae expanding culture method, microalgae expanding culture system and ecological restoration method

Abstract

The invention relates to the technical field of algae culture, in particular to a microalgae expanding culture method, a microalgae expanding culture system and an ecological restoration method. The microalgae expanding culture method comprises the following steps: inoculating a microalgae seed solution into a first culture solution, and carrying out first amplification treatment under the illumination condition of 100-500lux to prepare a first algae seed mixed solution; inoculating the first algae seed mixed solution into a second culture solution, and carrying out second amplification treatment under the illumination condition of 1000-3000 lux to prepare a second algae seed mixed solution; inoculating the second algae mixed solution into a third culture solution, and performing third amplification treatment at the pH value of 6.5-10 to prepare a third algae mixed solution; inoculating the third algae mixed solution into a fourth culture solution, and carrying out fourth amplification treatment under a stirring condition to prepare a fourth algae mixed solution; wherein the volumes of the first culture solution, the second culture solution, the third culture solution and the fourth culture solution are sequentially increased. According to the expanding culture method, the microalgae grow fast, and the culture period can be effectively shortened.

Description

Technical Field

[0001] This application relates to the field of algae cultivation technology, specifically to methods for expanding microalgae cultivation, microalgae cultivation systems, and ecological restoration methods. Background Art

[0002] Ecological restoration of coal mine soil mainly employs vegetation restoration, soil amendment application, and microbial remediation. Vegetation restoration involves planting herbaceous plants and shrubs to restore vegetation cover in coal mine spoil heaps; however, due to the poor soil quality and low nutrient content in coal mines, vegetation restoration can only improve the structure and fertility of the topsoil to a limited extent, with limited effectiveness. Soil amendment application involves applying organic fertilizers, chemical fertilizers, lime, and other soil amendments to improve the physical and chemical properties of the soil, increase soil fertility, and promote plant growth. However, this method relies heavily on chemical fertilizers and other soil amendments, which can lead to soil acidification and salinization, hindering sustainable development.

[0003] Compared to traditional vegetation restoration and soil conditioner application methods, microbial remediation offers advantages such as being eco-friendly, producing no secondary pollution, and contributing to ecosystem stability. Microalgae, as key participants in microbial remediation, can not only fix carbon dioxide and mitigate the greenhouse effect but also effectively remove pollutants such as nitrogen and phosphorus from water and soil, thus improving the ecological environment. However, microbial remediation requires large quantities of microalgae, which are currently cultivated on a large scale in single pipe or raceway ponds. This results in drawbacks such as slow growth, long cultivation cycles, and poor continuity. Summary of the Invention

[0004] Based on this, this application provides a method for expanding microalgae cultivation, a microalgae cultivation system, and an ecological restoration method. The microalgae cultivated using the method provided in this application exhibit rapid growth, effectively shorten the cultivation cycle, and demonstrate good continuity.

[0005] The first aspect of this application provides a method for the propagation of microalgae, comprising the following steps:

[0006] Microalgae seed solution was inoculated into the first culture medium and subjected to the first amplification treatment under light conditions of 100 lux to 500 lux to prepare the first algal seed mixture.

[0007] The first algal strain mixture was inoculated into the second culture medium and subjected to a second amplification treatment under a light condition of 1000 lux to 3000 lux to prepare the second algal strain mixture;

[0008] The second algal strain mixture was inoculated into the third culture medium and subjected to a third amplification treatment at a pH of 6.5-10 to prepare the third algal strain mixture.

[0009] The third algal strain mixture was inoculated into the fourth culture medium, and a fourth amplification treatment was carried out under stirring conditions to prepare the fourth algal strain mixture;

[0010] The volumes of the first culture medium, the second culture medium, the third culture medium, and the fourth culture medium increase sequentially.

[0011] In one embodiment, the first amplification process further comprises one or more of the following features:

[0012] (1) The temperature of the first amplification process is 15℃~35℃;

[0013] (2) The illumination wavelength of the first amplification process is 400nm~700nm;

[0014] (3) The microalgae seed solution is inoculated into the mixture prepared by the first culture medium, wherein the mass-volume concentration of the microalgae is 0.05 g / L to 0.4 g / L;

[0015] (4) In the first algal mixture, the mass-volume concentration of the microalgae is 0.5 g / L to 1.5 g / L;

[0016] (5) The first amplification process includes a first sub-amplification process, a second sub-amplification process and a third sub-amplification process performed sequentially. The volume of the first culture medium used in the first sub-amplification process, the second sub-amplification process and the third sub-amplification process is 200 mL to 5 L, and the volume of the first culture medium used in the first sub-amplification process, the second sub-amplification process and the third sub-amplification process increases sequentially.

[0017] In one embodiment, the first culture medium, the second culture medium, the third culture medium, and the fourth culture medium each independently comprise a solvent and the following components in terms of mass-volume concentration: 1 g / L to 2 g / L sodium nitrate, 0.02 g / L to 0.06 g / L potassium dihydrogen phosphate, 0.05 g / L to 0.1 g / L magnesium sulfate, 0.02 g / L to 0.05 g / L calcium chloride, and 0.004 g / L to 0.03 g / L trace substances;

[0018] The trace substances include one or more of citric acid, ferric ammonium citrate, disodium ethylenediaminetetraacetate, manganese sulfate, zinc sulfate, copper sulfate, sodium molybdate, and boric acid.

[0019] In one embodiment, the second amplification process further comprises one or more of the following features:

[0020] (1) In the atmosphere of the second amplification treatment, the volume concentration of carbon dioxide is 3%~8%;

[0021] (2) The second amplification process includes a first-level amplification process and a second-level amplification process performed sequentially. The volume of the second culture medium used in the first-level amplification process and the second-level amplification process is 30L~100L, and the volume of the second culture medium used in the first-level amplification process and the second-level amplification process increases sequentially.

[0022] (3) The equipment used for the second amplification treatment is a column-type photosynthetic reactor;

[0023] (4) In the second algal mixture, the mass-volume concentration of the microalgae is 1.8 g / L to 2.5 g / L;

[0024] (5) The first algal seed mixture is inoculated into the mixture prepared by the second culture medium, wherein the mass volume concentration of the microalgae is 0.05 g / L to 0.4 g / L.

[0025] In one embodiment, the pH value in the third amplification process step is controlled by the amount of carbon dioxide introduced.

[0026] And / or, the device for performing the third amplification treatment is a horizontal tube photosynthetic reactor;

[0027] And / or, the volume of the third culture medium is 0.5 tons to 4 tons; the third amplification process includes a first amplification process and a second amplification process performed sequentially, wherein the volume of the third culture medium used in the first amplification process and the second amplification process is independently 0.5 tons to 4 tons, and the volume of the third culture medium used in the first amplification process and the second amplification process increases sequentially.

[0028] And / or, the second algal strain mixture is inoculated into the mixture prepared by the third culture medium, wherein the mass-volume concentration of the microalgae is 0.05 g / L to 0.4 g / L;

[0029] And / or, in the third algal species mixture, the mass-volume concentration of the microalgae is 1.8 g / L to 2.5 g / L.

[0030] In one embodiment, the fourth amplification process rotation speed is 40 r / min to 80 r / min;

[0031] And / or, the device for performing the fourth amplification process is a raceway pool;

[0032] And / or, the temperature for performing the fourth amplification process is 15°C to 35°C;

[0033] And / or, the atmosphere in which the fourth amplification process is performed is air;

[0034] And / or, the volume of the fourth culture medium is 8 to 50 tons;

[0035] The fourth amplification process includes a first amplification process and a second amplification process performed sequentially. The volume of the fourth culture medium used in the first amplification process and the second amplification process is independently 8 to 50 tons, and the volume of the fourth culture medium used in the first amplification process and the second amplification process increases sequentially.

[0036] And / or, the liquid depth of the fourth culture medium is 20cm~50cm;

[0037] And / or, the third algal strain mixture is inoculated into a mixture prepared by the fourth culture medium, wherein the mass-volume concentration of the microalgae is 0.05 g / L to 0.4 g / L;

[0038] And / or, in the fourth algal species mixture, the mass-volume concentration of the microalgae is 0.6 g / L to 1 g / L.

[0039] In one embodiment, the microalgae include one or more of Scenedesmus, Chlorella, and nitrogen-fixing cyanobacteria.

[0040] A second aspect of this application provides a microalgae propagation system used in any embodiment of the first aspect of this application, comprising:

[0041] A conical flask culture container with a volume of 200 mL to 5 L is used to inoculate microalgae seed culture into a first culture medium and perform a first amplification treatment.

[0042] A column-type photosynthetic reactor, the volume of which is 30L~100L, is used to inoculate a first algal strain mixture into a second culture medium and perform a second amplification treatment.

[0043] A horizontal tube photosynthetic reactor, the volume of which is 0.5 tons to 4 tons, is used to inoculate a second algal strain mixture into a third culture medium and carry out a third amplification treatment.

[0044] The raceway pool has a volume of 8 to 50 tons and is used to inoculate the third algal strain mixture into the fourth culture medium and perform the fourth amplification treatment.

[0045] In one embodiment, the outlet of the column-type photosynthetic reactor is connected to the inlet of the horizontal tube-type photosynthetic reactor.

[0046] And / or, the outlet of the horizontal tubular photosynthetic reactor is connected to the inlet of the raceway pool.

[0047] A third aspect of this application provides an ecological restoration method, comprising the following steps:

[0048] The fourth algal strain mixture prepared by the propagation method described in any embodiment of the first aspect of this application is coated onto the soil surface.

[0049] The microalgae propagation method provided in this application has at least the following beneficial effects:

[0050] The expansion method provided in this application first performs a first expansion treatment under low light conditions. The relatively suitable treatment conditions and small volume of the first culture medium at this stage facilitate the rapid adaptation of the microalgae seed culture to its living environment, thus promoting its growth and reproduction. As the microalgae expand, the process transitions sequentially to second, third, and fourth culture media with increasing volumes. This process is accompanied by changes in the expansion treatment parameters, which work synergistically to provide suitable conditions for the sequential expansion of the microalgae. Simultaneously, this gradual expansion of the cultivation scale avoids the impact on microalgae growth caused by a sudden increase in culture medium volume or uneven resource distribution, ensuring that the microalgae are in an environment with a favorable growth space ratio. This facilitates the full utilization of nutrients, accelerates growth, and shortens the cultivation cycle. Furthermore, the close connection between each stage of the expansion treatment reduces the risk of contamination and the possibility of cultivation interruption due to improper operation or environmental changes. This creates a stable environment for microalgae growth and greatly improves the continuity of the entire expansion process.

[0051] Therefore, the propagation method provided in this application has a faster growth rate, can effectively shorten the cultivation cycle, and has good continuity. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 A flowchart illustrating a microalgae propagation method provided as an example in this application;

[0054] Figure 2 This is a schematic diagram of the structure of a microalgae propagation system provided as an example of this application.

[0055] In the diagram, 10 is a conical flask culture container; 20 is a column-type photosynthetic reactor; 30 is a horizontal tube-type photosynthetic reactor; and 40 is a raceway pool. Detailed Implementation

[0056] The following detailed description, in conjunction with specific embodiments, provides a more complete and clear account of the microalgae propagation method, microalgae propagation system, and ecological restoration method of this application. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of this application.

[0057] It should be understood that the terminology used in this application is merely for describing particular embodiments and is not intended to limit the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to limit the application.

[0058] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art described herein. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this application. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0059] In this article, "one or more" refers to any one, two or more of the listed items.

[0060] In this application, terms such as "first aspect," "second aspect," "third aspect," "fourth aspect," and "fifth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," "third," "fourth," and "fifth" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0061] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0062] Furthermore, for numerical ranges in this application, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this application. The upper and lower limits of these smaller ranges may be independently included or excluded from the range. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0063] Unless otherwise specified, the percentage content mentioned in this application refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures.

[0064] Unless otherwise specified, all percentage concentrations mentioned in this application refer to the final concentration. The final concentration refers to the proportion of the added component in the system after the addition of that component.

[0065] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows for temperature fluctuations within the precision range controlled by the instrument.

[0066] Coal mine soils have long been affected by coal mining activities, resulting in numerous problems such as structural damage, low fertility, and the accumulation of heavy metals and organic pollutants, impacting the ecological environment and sustainable land use. Microalgae bioremediation technology, leveraging the ability of microalgae to secrete extracellular polymers to improve soil structure, fix nitrogen and release nutrients to enhance fertility, adsorb and accumulate heavy metals and degrade organic pollutants to remove soil contaminants, form biofilms to maintain soil moisture and promote vegetation restoration, and possesses advantages such as environmental friendliness and low cost, has become an effective means of remediating coal mine soils, playing a significant role in the restoration and sustainable development of the ecological environment in coal mining areas. However, currently, microalgae are cultivated on a large scale in single pipe or raceway ponds, which suffers from drawbacks such as slow growth rate, long cultivation cycle, and poor continuity.

[0067] Based on this, the first aspect of this application provides a method for the propagation of microalgae, comprising the following steps:

[0068] S10. Inoculate the microalgae seed solution into the first culture medium and carry out the first amplification treatment under a light condition of 100 lux to 500 lux to prepare the first algae seed mixture.

[0069] S20. The first algal seed mixture is inoculated into the second culture medium and subjected to a second amplification treatment under a light condition of 1000 lux to 3000 lux to prepare the second algal seed mixture.

[0070] S30. The second algal strain mixture is inoculated into the third culture medium and subjected to a third amplification treatment at a pH of 6.5-10 to prepare the third algal strain mixture.

[0071] S40. The third algal strain mixture is inoculated into the fourth culture medium, and a fourth amplification treatment is carried out under stirring conditions to prepare the fourth algal strain mixture.

[0072] The volumes of the first culture medium, the second culture medium, the third culture medium, and the fourth culture medium increase sequentially.

[0073] In one example, the first amplification process includes a first sub-amplification process, a second sub-amplification process, and a third sub-amplification process performed sequentially. The volume of the first culture medium used in the first sub-amplification process, the second sub-amplification process, and the third sub-amplification process is independently 200 mL to 5 L, and the volume of the first culture medium used in the first sub-amplification process, the second sub-amplification process, and the third sub-amplification process increases sequentially.

[0074] Further, the volumes of the first culture medium used in the first sub-amplification treatment, the second sub-amplification treatment, and the third sub-amplification treatment are 300mL~700mL, 1.5L~2.5L, and 4L~5L, respectively. For example, the volume of the first culture medium used in the first sub-amplification treatment can be selected from any value between 300mL and 700mL. For example, the volume of the first culture medium used in the first sub-amplification treatment includes, but is not limited to, 300mL, 350mL, 400mL, 450mL, 500mL, 550mL, 600mL, 650mL, or 700mL, or any two of the above values ​​as endpoints. The volume of the first culture medium used in the second sub-diffusion treatment includes, but is not limited to, 1.5L, 1.8L, 2L, 2.2L, 2.4L, or 2.5L, or any two of the above values ​​as endpoints. The volume of the first culture medium used in the third sub-amplification treatment includes, but is not limited to, 4L, 4.5L, 4.8L, or 5L.

[0075] This application involves sequentially performing the first sub-amplification treatment, the second sub-amplification treatment, and the third sub-amplification treatment in a culture medium with increasing volume. This process can meet the gradually increasing space and nutrient requirements of microalgae during their natural growth, enabling the microalgae to gradually adapt to the constantly changing culture environment, thereby achieving efficient growth and mass reproduction.

[0076] See Figure 1 Further, step S10 includes: inoculating the microalgae seed solution into a first culture medium, and then sequentially performing a first sub-amplification treatment, a second sub-amplification treatment, and a third sub-amplification treatment under a light irradiation of 100 lux to 500 lux. Specifically, the first sub-amplification treatment involves inoculating the microalgae seed solution into a first culture medium with a volume of 300 mL to 700 mL; the second sub-amplification treatment involves inoculating the mixture after the first sub-amplification treatment into a first culture medium with a volume of 1.5 L to 2.5 L; and the third sub-amplification treatment involves inoculating the mixture after the second sub-amplification treatment into a first culture medium with a volume of 4 L to 5 L.

[0077] In one example, microalgae seed culture is inoculated into a mixture prepared from a first culture medium, wherein the mass-volume concentration of the microalgae is 0.05 g / L to 0.4 g / L. It is understood that "the mixture prepared from microalgae seed culture inoculated into the first culture medium" refers to the mass-volume concentration of the microalgae in the mixture before the amplification treatment. When the amplification treatment includes a first sub-amplification treatment, a second sub-amplification treatment, and a third sub-amplification treatment performed sequentially, the mass-volume concentration of the microalgae in the mixture before each of the first, second, and third sub-amplification treatments is independently 0.05 g / L to 0.4 g / L.

[0078] In one example, the microalgae concentration in the first algal strain mixture is 0.5 g / L to 1.5 g / L. For example, the microalgae concentration in the first algal strain mixture may include, but is not limited to, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.9 g / L, 1 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, or 1.5 g / L. Understandably, in the first amplification step, when the microalgae concentration reaches 0.5 g / L to 1.5 g / L, a subsequent amplification step is required.

[0079] Further, step S10 includes: inoculating the microalgae seed culture into 300mL~700mL of the first culture medium to achieve a microalgae concentration of 0.05g / L~0.4g / L, and then performing first-order amplification treatment under 100lux~500lux light conditions to achieve a microalgae concentration of 0.5g / L~1.5g / L; then inoculating the mixture after the first-order amplification treatment into 1.5L~2.5L of the first culture medium to achieve a microalgae concentration of 0.05g / L~0.4g / L. Then, under light conditions of 100 lux to 500 lux, a second amplification treatment was performed to achieve a microalgae concentration of 0.5 g / L to 1.5 g / L. The mixture after the second amplification treatment was then inoculated into 4 L to 5 L of the first culture medium to achieve a microalgae concentration of 0.05 g / L to 0.4 g / L. Then, under light conditions of 100 lux to 500 lux, a third amplification treatment was performed to achieve a microalgae concentration of 0.5 g / L to 1.5 g / L, thus preparing the first algal strain mixture.

[0080] In one example, the temperature of the first amplification process is 15°C to 35°C. For example, the temperature of the first amplification process includes, but is not limited to, 15°C, 18°C, 20°C, 22°C, 25°C, 28°C, 30°C, or 35°C. It is understood that when the first amplification process includes a first sub-diffusion process, a second sub-diffusion process, and a third sub-diffusion process performed sequentially, the process parameters for each step are the same as those for the first amplification process.

[0081] Understandably, the light intensity of the first amplification process can be selected from any value between 100 lux and 500 lux. For example, the light intensity of the first amplification process includes, but is not limited to, 100 lux, 200 lux, 220 lux, 230 lux, 240 lux, 250 lux, 260 lux, 280 lux, 300 lux, 320 lux, 350 lux, 380 lux, 400 lux, 420 lux, 450 lux, 480 lux, or 500 lux.

[0082] In one example, the illumination wavelength for the first amplification process is 400 nm to 700 nm. The illumination wavelength for the first amplification process includes, but is not limited to, 400 nm, 420 nm, 450 nm, 480 nm, 500 nm, 520 nm, 550 nm, 600 nm, 650 nm, or 700 nm. Understandably, the light source can be natural light or an LED, as long as the illumination wavelength or intensity meets the above range.

[0083] This application has discovered that performing the first amplification treatment under the specific temperature, light intensity, and light wavelength conditions described above provides a mild light condition that can prevent microalgae from being damaged by strong light during the initial growth stage, thus facilitating their balanced adaptation to the environment and initiation of growth.

[0084] In one example, the first culture medium comprises a solvent and the following components in mass-volume concentrations: 1 g / L to 2 g / L sodium nitrate, 0.02 g / L to 0.06 g / L potassium dihydrogen phosphate, 0.05 g / L to 0.1 g / L magnesium sulfate, 0.02 g / L to 0.05 g / L calcium chloride, and 0.004 g / L to 0.03 g / L trace substances.

[0085] The trace substances include one or more of citric acid, ferric ammonium citrate, disodium ethylenediaminetetraacetate, manganese sulfate, zinc sulfate, copper sulfate, sodium molybdate, and boric acid.

[0086] Further, the mass-volume concentration of sodium nitrate includes, but is not limited to, 1 g / L, 1.2 g / L, 1.5 g / L, 1.6 g / L, 1.8 g / L, or 2 g / L. The mass-volume concentration of potassium dihydrogen phosphate includes, but is not limited to, 0.02 g / L, 0.03 g / L, 0.04 g / L, 0.05 g / L, or 0.06 g / L. The mass-volume concentration of magnesium sulfate includes, but is not limited to, 0.05 g / L, 0.06 g / L, 0.07 g / L, 0.08 g / L, 0.09 g / L, or 0.1 g / L. The mass-volume concentration of calcium chloride includes, but is not limited to, 0.02 g / L, 0.03 g / L, 0.04 g / L, or 0.05 g / L. The mass-volume concentration of trace substances includes, but is not limited to, 0.004 g / L, 0.005 g / L, 0.008 g / L, 0.01 g / L, 0.015 g / L, 0.02 g / L, 0.025 g / L, or 0.03 g / L.

[0087] Furthermore, the solvent used in the first culture medium is water. Even further, the water used in the first culture medium includes, but is not limited to, tap water, distilled water, and ultrapure water.

[0088] For example, the first culture medium includes, but is not limited to, BG11 medium.

[0089] In one example, the apparatus for performing the first amplification process is a conical flask.

[0090] In one example, the volume concentration of carbon dioxide in the atmosphere of the second amplification process is 3% to 8%. Further, the volume concentration of carbon dioxide in the atmosphere of the second amplification process includes, but is not limited to, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, or 8%.

[0091] In one example, the second amplification process includes a first-stage amplification process and a second-stage amplification process performed sequentially, wherein the volume of the second culture medium used in the first-stage amplification process and the second-stage amplification process is independently 30L~100L, and the volume of the second culture medium used in the first-stage amplification process and the second-stage amplification process increases sequentially.

[0092] Further, the volumes of the second culture medium used in the first-stage amplification process and the second-stage amplification process are 30L~70L and 80L~120L, respectively. For example, the volume of the second culture medium used in the first-stage amplification process includes, but is not limited to, 30L, 32L, 33L, 35L, 38L, 40L, 42L, 45L, 48L, 50L, 52L, 55L, 58L, 60L, 62L, 65L, 68L, or 70L. For example, the volume of the second culture medium used in the second-stage amplification process includes, but is not limited to, 80L, 85L, 90L, 95L, 100L, 105L, 110L, 115L, or 120L.

[0093] See Figure 1 Further, step S20 includes: inoculating the first algal strain mixture into the second culture medium, and then sequentially performing a first-stage amplification treatment and a second-stage amplification treatment under a light irradiation of 1000 lux to 3000 lux. Specifically, the first-stage amplification treatment involves inoculating the first algal strain mixture into a second culture medium with a volume of 30 L to 70 L; the second-stage amplification treatment involves inoculating the mixture after the first-stage amplification treatment into a second culture medium with a volume of 80 L to 120 L.

[0094] In one example, the first algal strain mixture is inoculated into a mixture prepared with a second culture medium, wherein the mass-volume concentration of the microalgae is 0.05 g / L to 0.4 g / L. For example, the mass-volume concentration of the microalgae in the mixture includes, but is not limited to, 0.05 g / L, 0.1 g / L, 0.15 g / L, 0.2 g / L, 0.25 g / L, 0.3 g / L, 0.35 g / L, or 0.4 g / L. It is understood that when the second amplification treatment includes a first-stage amplification treatment and a second-stage amplification treatment performed sequentially, the mass-volume concentration of the microalgae in the mixture before the first-stage amplification treatment and before the second-stage amplification treatment is independently 0.05 g / L to 0.4 g / L.

[0095] In one example, the microalgae concentration in the second algal mixture is 1.8 g / L to 2.5 g / L. Understandably, in the second amplification process, when the microalgae concentration reaches 1.8 g / L to 2.5 g / L, a subsequent amplification process is required. When the second amplification process includes both a first-stage and a second-stage amplification process, a subsequent amplification process is required when the microalgae concentration in the mixture after each amplification process reaches 1.8 g / L to 2.5 g / L.

[0096] Further, step S20 includes: inoculating the first algal strain mixture into 30L~70L of a second culture medium to achieve a microalgal mass-volume concentration of 0.05g / L~0.4g / L, and then performing a first-stage amplification treatment under a light irradiation of 1000lux~3000lux to achieve a microalgal mass-volume concentration of 1.8g / L~2.5g / L; then inoculating the mixture after the first-stage amplification treatment into 80L~120L of a second culture medium to achieve a microalgal mass-volume concentration of 0.05g / L~0.4g / L, and then performing a second-stage amplification treatment under a light irradiation of 1000lux~3000lux to achieve a microalgal mass-volume concentration of 1.8g / L~2.5g / L, thereby preparing the second algal strain mixture.

[0097] In one example, the device used to perform the second amplification process is a column-type photosynthetic reactor.

[0098] Column-type photosynthetic reactors provide relatively stable and precisely controllable environmental conditions, such as light and carbon dioxide concentration, which are conducive to the rapid growth and reproduction of microalgae in a suitable environment. Furthermore, the column-type reactor provides a large gas-liquid contact area, ensuring that microalgae receive sufficient carbon dioxide and sunlight within a relatively small space. In addition, column-type photosynthetic reactors facilitate large-scale cultivation, meeting the high microalgal biomass requirements of ecological restoration methods.

[0099] In one example, the second culture medium comprises a solvent and the following components in mass-volume concentrations: 1 g / L to 2 g / L sodium nitrate, 0.02 g / L to 0.06 g / L potassium dihydrogen phosphate, 0.05 g / L to 0.1 g / L magnesium sulfate, 0.02 g / L to 0.05 g / L calcium chloride, and 0.004 g / L to 0.03 g / L trace substances.

[0100] The trace substances include one or more of citric acid, ferric ammonium citrate, disodium ethylenediaminetetraacetate, manganese sulfate, zinc sulfate, copper sulfate, sodium molybdate, and boric acid.

[0101] The second culture medium contains the same nutrients as the first culture medium, such as sodium nitrate, so it will not be described again here.

[0102] Furthermore, the solvent for the second culture medium is coal mine pit water.

[0103] This application finds that using coal mine pit water as the solvent for the second culture medium can provide rich nutrition for microalgae growth by utilizing the various minerals and trace elements it contains, while achieving environmentally friendly treatment and resource utilization of the mine pit water.

[0104] In one example, the pH value in the third amplification step is regulated by the amount of carbon dioxide introduced.

[0105] In one example, the device used for the third amplification process is a tubular photosynthetic reactor. The tubular reactor has a large surface area, allowing for more efficient use of sunlight for microalgal photosynthesis. Carbon dioxide is introduced into the reactor, and the gas flow rate is strictly controlled according to the pH value. This stage exhibits high gas mass transfer capacity, further increasing microalgal biomass.

[0106] In one example, the volume of the third culture medium is 0.5 to 4 tons; the third amplification process includes a first amplification process and a second amplification process performed sequentially, wherein the volume of the third culture medium used in the first amplification process and the second amplification process is independently 0.5 to 4 tons, and the volume of the third culture medium used in the first amplification process and the second amplification process increases sequentially.

[0107] Furthermore, the first amplification treatment involves inoculating the second algal strain mixture into a third culture medium with a volume of 0.5 to 2 tons; the second amplification treatment involves inoculating the mixture after the first amplification treatment into a third culture medium with a volume of 2.5 to 4 tons.

[0108] See Figure 1 Further, step S30 includes: inoculating the second algal strain mixture into the third culture medium, and then sequentially performing a first-stage amplification treatment and a second-stage amplification treatment at a pH of 6.5-10. The first-stage amplification treatment involves inoculating the second algal strain mixture into a third culture medium with a volume of 0.5 to 2 tons; the second-stage amplification treatment involves inoculating the mixture after the first-stage amplification treatment into a third culture medium with a volume of 2.5 to 4 tons.

[0109] In one example, the second algal strain mixture is inoculated into a mixture prepared with a third culture medium, wherein the mass-volume concentration of the microalgae is 0.05 g / L to 0.4 g / L. When the amplification process includes a first amplification process and a second amplification process performed sequentially, the mass-volume concentration of the microalgae in the mixture before the first amplification process and before the second amplification process is independently 0.05 g / L to 0.4 g / L.

[0110] In one example, the microalgae concentration in the third algal strain mixture is 1.8 g / L to 2.5 g / L. Understandably, in the third amplification process, when the microalgae concentration reaches 1.8 g / L to 2.5 g / L, a subsequent amplification process is required. When the third amplification process includes both the first and second amplification processes, a subsequent amplification process is required when the microalgae concentration in the mixture after each amplification process reaches 1.8 g / L to 2.5 g / L.

[0111] In one example, the third culture medium comprises a solvent and the following components in mass-volume concentrations: 1 g / L to 2 g / L sodium nitrate, 0.02 g / L to 0.06 g / L potassium dihydrogen phosphate, 0.05 g / L to 0.1 g / L magnesium sulfate, 0.02 g / L to 0.05 g / L calcium chloride, and 0.004 g / L to 0.03 g / L trace substances.

[0112] The trace substances include one or more of citric acid, ferric ammonium citrate, disodium ethylenediaminetetraacetate, manganese sulfate, zinc sulfate, copper sulfate, sodium molybdate, and boric acid.

[0113] The nutrients in the third culture medium, such as sodium nitrate, are the same as those in the first culture medium, so they will not be described again here.

[0114] Furthermore, the solvent for the third culture medium is coal mine pit water.

[0115] In one example, the rotation speed of the fourth amplification process is 40 r / min to 80 r / min. The rotation speed of the fourth amplification process includes, but is not limited to, 40 r / min, 50 r / min, 55 r / min, 60 r / min, 65 r / min, 70 r / min, 75 r / min, or 80 r / min. Amplification under stirring conditions ensures the fluidity of the algal solution and uniform light distribution. Furthermore, the raceway pool design takes into account light and temperature fluctuations under outdoor conditions, which is crucial for ensuring continuous and efficient microalgae growth and for enabling vegetation irrigation and ecological restoration once the algal solution concentration in the raceway pool meets irrigation requirements.

[0116] In one example, the device performing the fourth amplification process is a runway pool.

[0117] In one example, the temperature for performing the fourth amplification process is 15°C to 35°C. The temperature for the fourth amplification process includes, but is not limited to, 15°C, 17°C, 20°C, 22°C, 25°C, 28°C, 30°C, 33°C, or 35°C.

[0118] In one example, the atmosphere in which the fourth amplification process is performed is air. Understandably, the runway pool can be placed outdoors to perform the fourth amplification process in an air atmosphere.

[0119] In one example, the volume of the fourth culture medium is 8 to 50 tons.

[0120] In one example, the liquid depth of the fourth culture medium is 20 cm to 50 cm. For example, the liquid depth of the fourth culture medium includes, but is not limited to, 20 cm, 25 cm, 30 cm, 35 cm, 40 cm, 45 cm, or 50 cm.

[0121] In one example, the fourth amplification process uses a fourth culture medium with a volume of 8 to 50 tons.

[0122] Further, step S40 includes: inoculating the third algal strain mixture into 8 to 50 tons of the fourth culture medium to make the mass-volume concentration of microalgae 0.05 g / L to 0.4 g / L, and then performing a fourth amplification treatment under stirring to make the mass-volume concentration of microalgae reach 0.6 g / L to 1 g / L, thereby preparing the fourth algal strain mixture.

[0123] In another example, the fourth amplification process includes a first amplification process and a second amplification process performed sequentially, wherein the volume of the fourth culture medium used in the first amplification process and the second amplification process is independently 8 to 50 tons, and the volume of the fourth culture medium used in the first amplification process and the second amplification process increases sequentially.

[0124] See Figure 1 Further, step S40 includes: inoculating the third algal strain mixture into the fourth culture medium, and then sequentially performing the first amplification treatment and the second amplification treatment under stirring conditions. Specifically, the first amplification treatment involves inoculating the third algal strain mixture into a fourth culture medium with a volume of 8 to 30 tons; the second amplification treatment involves inoculating the mixture after the first amplification treatment into a fourth culture medium with a volume of 35 to 50 tons.

[0125] In one example, the third algal strain mixture is inoculated into a mixture prepared with a fourth culture medium, wherein the mass-volume concentration of the microalgae is 0.05 g / L to 0.4 g / L. For example, the mass-volume concentration of the microalgae in the mixture includes, but is not limited to, 0.05 g / L, 0.1 g / L, 0.15 g / L, 0.2 g / L, 0.25 g / L, 0.3 g / L, 0.35 g / L, or 0.4 g / L. It is understood that when the fourth amplification treatment includes a first amplification treatment and a second amplification treatment performed sequentially, the mass-volume concentration of the microalgae in the mixture before the first amplification treatment and before the second amplification treatment is independently 0.05 g / L to 0.4 g / L.

[0126] In one example, the microalgae concentration in the fourth algal strain mixture is 0.6 g / L to 1 g / L. Understandably, in the fourth amplification process, the amplification process ends when the microalgae concentration reaches 0.6 g / L to 1 g / L. When the fourth amplification process includes a first amplification process and a second amplification process, a subsequent amplification process is required when the microalgae concentration in the mixture after each amplification process reaches 0.6 g / L to 1 g / L.

[0127] See Figure 1 Further, step S40 includes: inoculating the third algal strain mixture into 8 to 30 tons of a fourth culture medium to achieve a microalgal concentration of 0.05 g / L to 0.4 g / L; then performing a first-step amplification treatment under stirring to achieve a microalgal concentration of 0.6 g / L to 1 g / L; then inoculating the mixture after the first-step amplification treatment into 8 to 30 tons of the fourth culture medium to achieve a microalgal concentration of 0.05 g / L to 0.4 g / L; then performing a second-step amplification treatment under stirring to achieve a microalgal concentration of 0.6 g / L to 1 g / L, thus preparing the fourth algal strain mixture.

[0128] In one example, the fourth culture medium comprises a solvent and the following components in mass-volume concentrations: 1 g / L to 2 g / L sodium nitrate, 0.02 g / L to 0.06 g / L potassium dihydrogen phosphate, 0.05 g / L to 0.1 g / L magnesium sulfate, 0.02 g / L to 0.05 g / L calcium chloride, and 0.004 g / L to 0.03 g / L trace substances.

[0129] The trace substances include one or more of citric acid, ferric ammonium citrate, disodium ethylenediaminetetraacetate, manganese sulfate, zinc sulfate, copper sulfate, sodium molybdate, and boric acid.

[0130] The nutrients in the fourth culture medium, such as sodium nitrate, are the same as those in the first culture medium, so they will not be described again here.

[0131] Furthermore, the solvent for the fourth culture medium is coal mine pit water.

[0132] In one example, the microalgae include one or more of Scenedesmus, Chlorella, and nitrogen-fixing cyanobacteria.

[0133] See Figure 2 A second aspect of this application provides a microalgae propagation system used in any of the exemplary propagation methods of the first aspect of this application, comprising:

[0134] A conical flask culture container 10, the volume of which is 200mL~5L, is used to inoculate microalgae seed liquid into a first culture medium and perform a first amplification treatment.

[0135] A column-type photosynthetic reactor 20, with a volume of 30L to 100L, is used to inoculate a first algal strain mixture into a second culture medium and perform a second amplification treatment.

[0136] A horizontal tube photosynthetic reactor 30, the volume of which is 0.5 tons to 4 tons, is used to inoculate the second algal strain mixture into the third culture medium and carry out the third amplification treatment.

[0137] The raceway pool 40 has a volume of 8 to 50 tons and is used to inoculate the third algal strain mixture into the fourth culture medium and perform the fourth amplification treatment.

[0138] In one example, the conical flask culture container 10 includes three conical flasks of different volumes. For example, the conical flask culture container 10 includes a first set of conical flasks, a second set of conical flasks, and a third set of conical flasks.

[0139] Furthermore, the volume of the first group of conical flasks is 300 mL to 1 L. The volume of the second group of conical flasks is 1.5 L to 3 L. The volume of the third group of conical flasks is 4 L to 6 L. Understandably, the volume of each group of conical flasks is adapted to the volume of the first culture medium in the first, second, and third sub-amplification treatment steps, respectively. Understandably, the number of conical flasks in each group can be one or more.

[0140] In one example, the column photosynthetic reactor 20 includes two column photosynthetic reactor devices of different volumes. For example, the column photosynthetic reactor 20 includes a first set of column photosynthetic reactor devices and a second set of column photosynthetic reactor devices.

[0141] Furthermore, the volume of the first group of column-type photosynthetic reactors is 30L~75L. The volume of the second group of column-type photosynthetic reactors is 80L~125L. Understandably, the volume of each group of column-type photosynthetic reactors is adapted to the volume of the second culture medium in the first-stage amplification treatment and the second-stage amplification treatment, respectively. Understandably, the number of column-type photosynthetic reactors in each group can be one or more.

[0142] In one example, the horizontal tubular photosynthetic reactor 30 includes two horizontal tubular photosynthetic reactor devices of different volumes. For example, the horizontal tubular photosynthetic reactor 30 includes a first set of horizontal tubular photosynthetic reactor devices and a second set of horizontal tubular photosynthetic reactor devices.

[0143] Furthermore, the volume of the first group of horizontal tubular photosynthetic reactors ranges from 0.5 tons to 2.3 tons. The volume of the second group of horizontal tubular photosynthetic reactors ranges from 2.5 tons to 4.5 tons. Understandably, the volume of each group of horizontal tubular photosynthetic reactors is adapted to the volume of the third culture medium in the first and second amplification treatments, respectively. Understandably, the number of horizontal tubular photosynthetic reactors in each group can be one or more.

[0144] In one example, the runway pool 40 includes one or more runway pool devices. The volume of the runway pool device is between 8 tons and 55 tons. Understandably, the volume of the runway pool device is adapted to the volume of the fourth culture medium in the fourth amplification process.

[0145] In another example, runway pool 40 includes two runway pool assemblies of different volumes. For example, runway pool 40 includes a first set of runway pool assemblies and a second set of runway pool assemblies.

[0146] Furthermore, the volume of the first set of raceway pool devices ranges from 8 tons to 33 tons. The volume of the second set of raceway pool devices ranges from 35 tons to 55 tons. Understandably, the volume of each set of raceway pool devices is adapted to the volume of the fourth culture medium in the first and second amplification processes, respectively.

[0147] Understandably, the number of runway pool devices in each group can be one or more.

[0148] In one example, the outlet of the column-type photosynthetic reactor is connected to the inlet of the horizontal tube-type photosynthetic reactor.

[0149] In one example, the outlet of the horizontal tubular photosynthetic reactor is connected to the inlet of the raceway pool.

[0150] The propagation method or propagation system provided in this application has at least the following beneficial effects:

[0151] (1) High-efficiency microalgae production: The cultivation scale is gradually expanded through a multi-stage expansion system, from small conical flasks to outdoor racetrack pools, ensuring that microalgae can grow rapidly under optimal environmental conditions. This graded expansion model can realize large-scale production of microalgae biomass to meet the needs of ecological restoration projects.

[0152] (2) High resource utilization efficiency: The system uses coal mine pit water as a microalgae culture medium, which effectively utilizes the nutrients in the wastewater, not only reducing the use of external water sources, but also improving the recycling rate of resources.

[0153] (3) Improve soil quality: Microalgae biomass is rich in a variety of nutrients required by plants, such as nitrogen, phosphorus, and potassium. Applying it to coal mine soil can significantly improve soil fertility and promote vegetation restoration. At the same time, the biological crust formed by microalgae on the soil surface helps prevent soil erosion and improve the soil microenvironment.

[0154] A third aspect of this application provides an ecological restoration method, comprising the following steps:

[0155] The fourth algal strain mixture prepared by the propagation method described in any of the first aspects of this application is coated onto the soil surface.

[0156] This application achieves large-scale microalgae production by progressively increasing the biomass of cultivated microalgae, and also improves resource utilization efficiency by utilizing nutrients in coal mine wastewater. Finally, the microalgae are sprayed onto the grassland of coal mine spoil heaps, where their rich nutrients and soil crust-forming ability significantly improve soil structure and fertility, promoting vegetation restoration. Furthermore, the microalgae can absorb carbon dioxide through photosynthesis, reducing greenhouse gas emissions.

[0157] The following detailed embodiments illustrate this application in more detail. It should also be understood that the following embodiments are for further explanation only and should not be construed as limiting the scope of protection of this application. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of this application fall within the scope of protection of this application. The specific process parameters, etc., in the following embodiments are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not necessarily limited to the specific values ​​in the embodiments below.

[0158] Example

[0159] Microalgae propagation systems: such as Figure 2 As shown. Specifically, the microalgae propagation system includes: conical flask culture containers 10, column-type photosynthetic reactors 20, horizontal tube-type photosynthetic reactors 30, and raceway tanks 40. The conical flask culture containers 10 include a first group of conical flasks, a second group of conical flasks, and a third group of conical flasks. The first group of conical flasks has a volume of 500 mL and contains 10 conical flasks. The second group of conical flasks has a volume of 2 L and contains 10 conical flasks. The third group of conical flasks has a volume of 5 L and contains 20 conical flasks.

[0160] The column-type photosynthetic reactor 20 includes a first group of column-type photosynthetic reactor devices and a second group of column-type photosynthetic reactor devices. The first group of column-type photosynthetic reactor devices has a volume of 50L and includes two column-type photosynthetic reactor devices. The second group of column-type photosynthetic reactor devices has a volume of 100L and also includes two column-type photosynthetic reactor devices.

[0161] The horizontal tubular photosynthetic reactor 30 includes a first group of horizontal tubular photosynthetic reactor devices and a second group of horizontal tubular photosynthetic reactor devices. The first group of horizontal tubular photosynthetic reactor devices has a volume of 1 ton and includes two horizontal tubular photosynthetic reactor devices. The second group of horizontal tubular photosynthetic reactor devices has a volume of 4 tons and also includes two horizontal tubular photosynthetic reactor devices.

[0162] The runway pool 40 includes three runway pool units. The volume of each runway pool unit is 50 tons.

[0163] Microalgae propagation methods:

[0164] First amplification treatment: Microalgae seed culture (Chlorella vulgaris) was inoculated into 400 mL of the first culture medium (tap water, standard BG11 medium, placed in the first set of Erlenmeyer flasks) to achieve a microalgae concentration of 0.1 g / L. Then, first amplification treatment was performed at 25℃, 200 lux light intensity, and a light wavelength of 400 nm–700 nm to achieve a microalgae concentration of 1.5 g / L. The mixture after the first amplification treatment was then inoculated into 1.8 L of the first culture medium (standard BG11 medium, placed in the second set of Erlenmeyer flasks) to achieve a microalgae concentration of 0.1 g / L. L, and then the second sub-amplification treatment was carried out at 25℃, 200 lux light intensity, and light wavelength of 400nm~700nm to achieve a microalgae mass-volume concentration of 1.5 g / L; then the mixture after the second sub-amplification treatment was inoculated into 4.5 L of the first culture medium (standard BG11 medium, placed in the third group of conical flasks) to achieve a microalgae mass-volume concentration of 0.1 g / L. Then the third sub-amplification treatment was carried out at 25℃, 200 lux light intensity, and light wavelength of 400nm~700nm to achieve a microalgae mass-volume concentration of 1.5 g / L, thus preparing the first algae seed mixture.

[0165] Second amplification treatment: The first algal strain mixture was inoculated into 45L of the second culture medium (coal mine quarry water as solvent, standard BG11 medium, placed in the first column-type photosynthetic reactor device) to achieve a microalgal mass-volume concentration of 0.1 g / L. Then, under the conditions of 2000 lux light and 5% carbon dioxide volume concentration, the first-stage amplification treatment was carried out to achieve a microalgal mass-volume concentration of 2 g / L. The mixture after the first-stage amplification treatment was inoculated into 95L of the second culture medium (coal mine quarry water as solvent, standard BG11 medium, placed in the second column-type photosynthetic reactor device) to achieve a microalgal mass-volume concentration of 0.1 g / L. Then, under the conditions of 1000 lux~3000 lux light and 5% carbon dioxide volume concentration, the second-stage amplification treatment was carried out to achieve a microalgal mass-volume concentration of 2 g / L, thus preparing the second algal strain mixture.

[0166] The third amplification treatment: The second algal strain mixture was inoculated into 0.9 tons of the third culture medium (coal mine quarry water as solvent, standard BG11 medium, placed in the first group of horizontal tube photosynthetic reactor devices), and then the first amplification treatment was carried out at pH 8.5 (if the pH exceeds 8.5, CO2 can be introduced in 30-second cycles at a flow rate of approximately 300 ml / min until the pH drops below 8.5 and then the gas introduction is stopped), so that the mass-volume concentration of microalgae reaches 2 g / L; the mixture after the first amplification treatment was inoculated into 3.5 tons of the third culture medium (coal mine quarry water as solvent, standard BG11 medium, placed in the second group of horizontal tube photosynthetic reactor devices), so that the mass-volume concentration of microalgae is 0.1 g / L, and then the second amplification treatment was carried out at pH 8.5, so that the mass-volume concentration of microalgae reaches 2 g / L, thus preparing the third algal strain mixture.

[0167] Fourth amplification treatment: The third algal strain mixture was inoculated into 45 tons of fourth culture medium (coal mine pit water as solvent, liquid depth of about 40 cm, standard BG11 medium, placed in a raceway pool device) to make the mass volume concentration of microalgae 0.1 g / L. Then, the first amplification treatment was carried out under stirring at 60 r / min to make the mass volume concentration of microalgae reach 0.6 g / L, thus preparing the fourth algal strain mixture.

[0168] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0169] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for propagating microalgae, characterized in that, Includes the following steps: Microalgae seed solution was inoculated into the first culture medium and subjected to the first amplification treatment under light conditions of 100 lux to 500 lux to prepare the first algal seed mixture. The first algal strain mixture was inoculated into the second culture medium and subjected to a second amplification treatment under a light condition of 1000 lux to 3000 lux to prepare the second algal strain mixture; The second algal strain mixture was inoculated into the third culture medium and subjected to a third amplification treatment at a pH of 6.5-10 to prepare the third algal strain mixture. The third algal strain mixture was inoculated into the fourth culture medium, and a fourth amplification treatment was carried out under stirring conditions to prepare the fourth algal strain mixture; The volumes of the first culture medium, the second culture medium, the third culture medium, and the fourth culture medium increase sequentially.

2. The method for propagating microalgae according to claim 1, characterized in that, The first amplification process also has one or more of the following features: (1) The temperature of the first amplification process is 15℃~35℃; (2) The illumination wavelength of the first amplification process is 400nm~700nm; (3) Inoculate the microalgae seed solution into the mixture prepared by the first culture medium, and the mass-volume concentration of the microalgae is 0.05 g / L to 0.4 g / L; (4) In the first algal strain mixture, the mass-volume concentration of microalgae is 0.5 g / L to 1.5 g / L; (5) The first amplification process includes a first sub-amplification process, a second sub-amplification process and a third sub-amplification process performed sequentially. The volume of the first culture medium used in the first sub-amplification process, the second sub-amplification process and the third sub-amplification process is 200 mL to 5 L, and the volume of the first culture medium used in the first sub-amplification process, the second sub-amplification process and the third sub-amplification process increases sequentially.

3. The method for propagating microalgae according to claim 1, characterized in that, The first culture medium, the second culture medium, the third culture medium, and the fourth culture medium each independently comprise a solvent and the following components in terms of mass-volume concentration: 1 g / L to 2 g / L sodium nitrate, 0.02 g / L to 0.06 g / L potassium dihydrogen phosphate, 0.05 g / L to 0.1 g / L magnesium sulfate, 0.02 g / L to 0.05 g / L calcium chloride, and 0.004 g / L to 0.03 g / L trace substances; The trace substances include one or more of citric acid, ferric ammonium citrate, disodium ethylenediaminetetraacetate, manganese sulfate, zinc sulfate, copper sulfate, sodium molybdate, and boric acid.

4. The method for propagating microalgae according to claim 1, characterized in that, The second amplification process also has one or more of the following features: (1) In the atmosphere of the second amplification treatment, the volume concentration of carbon dioxide is 3%~8%; (2) The second amplification process includes a first-level amplification process and a second-level amplification process performed sequentially. The volume of the second culture medium used in the first-level amplification process and the second-level amplification process is 30L~100L, and the volume of the second culture medium used in the first-level amplification process and the second-level amplification process increases sequentially. (3) The equipment used for the second amplification treatment is a column-type photosynthetic reactor; (4) In the second algal mixture, the mass-volume concentration of microalgae is 1.8 g / L to 2.5 g / L; (5) The first algal seed mixture is inoculated into the mixture prepared by the second culture medium, and the mass volume concentration of microalgae is 0.05 g / L to 0.4 g / L.

5. The method for propagating microalgae according to claim 1, characterized in that, The pH value in the third amplification process is controlled by the amount of carbon dioxide introduced. And / or, the device for performing the third amplification treatment is a horizontal tube photosynthetic reactor; And / or, the volume of the third culture medium is 0.5 tons to 4 tons; the third amplification process includes a first amplification process and a second amplification process performed sequentially, wherein the volume of the third culture medium used in the first amplification process and the second amplification process is independently 0.5 tons to 4 tons, and the volume of the third culture medium used in the first amplification process and the second amplification process increases sequentially. And / or, the second algal strain mixture is inoculated into the mixture prepared by the third culture medium, and the mass-volume concentration of microalgae is 0.05 g / L to 0.4 g / L; And / or, in the third algal species mixture, the mass-volume concentration of microalgae is 1.8 g / L to 2.5 g / L.

6. The method for propagating microalgae according to claim 1, characterized in that, The rotation speed of the fourth amplification process is 40 r / min to 80 r / min; And / or, the device for performing the fourth amplification process is a raceway pool; And / or, the temperature for performing the fourth amplification process is 15°C to 35°C; And / or, the atmosphere in which the fourth amplification process is performed is air; And / or, the volume of the fourth culture medium is 8 to 50 tons; The fourth amplification process includes a first amplification process and a second amplification process performed sequentially. The volume of the fourth culture medium used in the first amplification process and the second amplification process is independently 8 to 50 tons, and the volume of the fourth culture medium used in the first amplification process and the second amplification process increases sequentially. And / or, the liquid depth of the fourth culture medium is 20cm~50cm; And / or, the third algal strain mixture is inoculated into the mixture prepared by the fourth culture medium, and the mass-volume concentration of microalgae is 0.05 g / L to 0.4 g / L; And / or, in the fourth algal species mixture, the mass-volume concentration of microalgae is 0.6 g / L to 1 g / L.

7. The method for propagating microalgae according to any one of claims 1 to 6, characterized in that, The microalgae include one or more of Scenedesmus, Chlorella, and nitrogen-fixing cyanobacteria.

8. A microalgae propagation system, characterized in that, include: A conical flask culture container with a volume of 200 mL to 5 L is used to inoculate microalgae seed culture into a first culture medium and perform a first amplification treatment. A column-type photosynthetic reactor, the volume of which is 30L~100L, is used to inoculate a first algal strain mixture into a second culture medium and perform a second amplification treatment. A horizontal tube photosynthetic reactor, the volume of which is 0.5 tons to 4 tons, is used to inoculate a second algal strain mixture into a third culture medium and carry out a third amplification treatment. The raceway pool has a volume of 8 to 50 tons and is used to inoculate the third algal strain mixture into the fourth culture medium and perform the fourth amplification treatment.

9. The microalgae propagation system according to claim 8, characterized in that, The outlet of the column-type photosynthetic reactor is connected to the inlet of the horizontal tube-type photosynthetic reactor. And / or, the outlet of the horizontal tubular photosynthetic reactor is connected to the inlet of the raceway pool.

10. An ecological restoration method, characterized in that, Includes the following steps: The fourth algal strain mixture prepared by the propagation method according to any one of claims 1 to 7 is coated on the soil surface.

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