Photo-anaerobic bioreactor and method thereof

Abstract

The invention discloses a sunlight and artificial light source-enhanced photo-anaerobic bioreactor and an application method thereof, and aims to enhance the absorption and conversion efficiency of a photosensitive material on light energy by combining the multispectral synergistic effect of sunlight and an artificial light source, so as to improve the overall efficiency of photo-anaerobic biological reaction. Particularly, the algae organic matter is introduced as a light-sensitive material, the reaction efficiency can be improved under the illumination condition, and the reaction process is optimized by accurately controlling the spectral range.

Description

Technical Field

[0001] The present invention relates to the field of photo - anaerobic bioreactors, and particularly to a photo - anaerobic bioreactor and a method thereof based on the synergistic effect of algal residues and mixed light sources. Background Art

[0002] Under the current technical background, anaerobic digestion is widely used for organic matter decomposition and bio - energy production, but its efficiency is often limited by microbial activity. As an important factor affecting microbial metabolism, light gradually shows its potential in enhancing anaerobic reactions. However, most current anaerobic digestion processes are limited to light - free environments or simply rely on sunlight and artificial light sources, failing to fully explore the synergistic enhancement effect of photosensitive materials.

[0003] UASB anaerobic reaction device based on intermittent optical fiber solar transmission CN116062911A: A UASB anaerobic reaction device based on intermittent optical fiber solar transmission is mainly used for the treatment of organic wastewater. This device uniquely uses sunlight and, through an external daylighting device and an optical fiber system, directly transmits light energy to the light - emitting device inside the device to provide the light energy required by photosynthetic bacteria. However, there are still deficiencies in the light energy utilization efficiency of this device. Specifically, the spectral range transmitted by its optical fiber is fixed, failing to meet the requirements of different photosynthetic bacteria for specific - wavelength light during metabolism, resulting in limited light energy capture and conversion efficiency. In addition, the dependence on a single light source makes the performance of the device unstable when the light conditions change. These deficiencies limit the wide application of this technology in complex wastewater treatment scenarios.

[0004] A novel photo - fermentation up - flow anaerobic reactor CN219972012U: Based on the traditional up - flow anaerobic reactor, this device adds an anaerobic coupled photocatalytic reaction zone. Through fixed fillers coated with visible - light catalysts and simulated solar lamps, the COD removal rate of wastewater is increased by 20% - 30%. A sludge bed, a three - phase separator, and a water distribution system are set inside the reactor, which can effectively separate sludge, gas, and treated wastewater, and at the same time recover biogas, optimizing the efficiency of wastewater treatment and resource utilization. However, this device has certain deficiencies: the photocatalytic reaction has a high dependence on simulated solar lamps, with high energy consumption and insufficient utilization of natural light resources; the catalyst coating on the surface of the filler may be affected by coverage or aging during long - term operation, resulting in a decline in catalytic performance.

[0005] A photocatalytic high-efficiency anaerobic reactor CN114804325A: This device promotes sewage oxidation through blue light irradiation, significantly improving the anaerobic reaction efficiency and sewage treatment effect. Its structure includes two inlet pipes, one connected to the reaction mechanism, and the other installed with a lighting mechanism and equipped with an automatic cleaning device to remove stains on the lighting components and maintain the blue light irradiation efficiency. In addition, the device is designed with high-efficiency and low-efficiency reaction zones, and the water treatment process is optimized through a three-phase separator. To prevent blockage, the reactor is also equipped with an automatic flushing system, which can collect and discharge impurities in the sewage to ensure the stability and smoothness of the treatment process. This design combines mechanics and photochemistry to improve the automation level and energy efficiency of sewage treatment. However, this device still has limitations in practical applications. First, the lighting system relies heavily on the cleaning device, and the complex operating environment may lead to a decrease in cleaning efficiency, affecting the blue light irradiation effect. Second, the automatic flushing system of the reactor is complexly designed, and the maintenance difficulty may increase during long-term operation.

[0006] A photosynthetic anaerobic bioreactor CN208684947U: This device is designed for the cultivation of photosynthetic anaerobic bacteria and consists of an outer tank and an inner tank, forming an annular cavity. An LED light source and an ultraviolet lamp are set in the center of the inner tank, and the light source intensity is controlled by an adjustment switch to optimize the lighting environment. The reactor improves the light source utilization rate through the transparent sidewall design, shortens the fermentation cycle, significantly improves the fermentation efficiency and the microbial growth rate, and reduces the production cost at the same time. The tank structure is convenient for cleaning and sterilization, ensuring the convenience and safety of operation. However, during long-term operation of the device, the transparent sidewall may be contaminated or affected by light attenuation, affecting the light effect; in addition, although the wavelength adaptation of the light source is flexible, it may be difficult to fully cover the needs of different strains, and there are certain limitations in special applications.

[0007] A lighting-type anaerobic treatment system for food waste CN113150964B: This system consists of an anaerobic treatment tank and a gas storage tank. The anaerobic treatment tank is connected to the gas storage tank through a pipeline. A horizontal stirring shaft and stirring blades are provided in the tank to promote the mixing and fermentation of materials. The innovation lies in that the sidewall of the anaerobic treatment tank is made of a transparent and light-transmitting material, and a movable light source strip is installed. The light source strip moves with the conveyor belt to achieve dynamic adjustment of the lighting intensity and distribution. This design activates the microbial activity through lighting, effectively improving the anaerobic fermentation efficiency and the resource treatment capacity of food waste. At the same time, combined with the stirring function, it ensures the uniformity of the fermentation environment. However, there may be some problems during the operation of this system: the chute of the light source strip and the conveyor belt are prone to wear and reduced efficiency in a high-humidity environment, increasing the equipment maintenance frequency, which may pose a certain challenge to the continuous and efficient operation of the system. Summary of the Invention

[0008] Algal organic matter is a type of natural photosensitive material, rich in photoactive components such as carotenoids and chlorophyll. It can efficiently absorb and convert light energy, and at the same time enhance the activity of microorganisms through light stimulation, optimizing the anaerobic digestion process. In addition, algal organic matter can also promote key metabolic pathways by interacting with anaerobic microorganisms, thereby improving the energy recovery efficiency. By integrating sunlight and artificial light sources through an optical fiber system and introducing algal organic matter as the photosensitive material, precise regulation of light intensity can be achieved, while significantly enhancing the light energy utilization efficiency and overcoming the deficiencies of single light sources in terms of energy consumption, stability, and environmental adaptability. This new type of light-enhanced anaerobic reaction system provides a new technical path for improving anaerobic digestion efficiency and reducing energy consumption, and is of great significance for environmental protection and sustainable development.

[0009] The object of the present invention is to provide a photo-anaerobic bioreactor enhanced by sunlight in cooperation with an artificial light source and its application method, aiming to enhance the absorption and conversion efficiency of light energy by the photosensitive material through the multi-spectral synergistic effect of combining sunlight and artificial light sources, thereby improving the overall efficiency of the photo-anaerobic biological reaction. In particular, the present invention introduces algal organic matter as the photosensitive material, which can improve the reaction efficiency under light conditions and optimize the reaction process by precisely controlling the spectral range.

[0010] In a first aspect, the present invention provides a photo-anaerobic bioreactor, comprising a transparent or semi-transparent reactor main body, and is equipped with a light source system, a photosensitive material system, a stirring system, a monitoring system, and a control system. The light source system includes a sunlight introduction system and an artificial light source, and the photosensitive material system includes algal organic matter.

[0011] In some embodiments, the algal organic matter includes: the algal organic matter is obtained by culturing cyanobacteria and green algae and their derivatives, including but not limited to pigments (such as chlorophyll, phycocyanin, phycoerythrin), extracellular polysaccharides, carotenoids, and other metabolic active substances produced by algae during metabolism. These algal organic matters can absorb light energy and convert it into chemical energy, enhancing the promotion of light on the photo-anaerobic biological reaction. Their photosensitive characteristics enable the reactor to achieve light energy enhancement under multi-spectral conditions, providing support for the metabolism of microorganisms.

[0012] The algal organic matter can be obtained by self-cultivation or further processed after being obtained from a factory. When self-cultivating, the growth of algae is promoted by regulating conditions such as light, temperature, and nutrients; when obtaining from a factory, preliminarily treated algal biomass raw materials can be used, and through steps including but not limited to heat treatment, centrifugal separation, and filtration concentration, the active ingredients inside the algal cells are released and extracted. This diverse acquisition method ensures the purity and photosensitive activity of the algal organic matter, providing efficient support for the photo-anaerobic biological reaction. These organic matters can absorb light energy and convert it into chemical energy, enhancing the promotion of light on the photo-anaerobic biological reaction. The photosensitive characteristics of the algal organic matter enable the reactor to carry out light energy enhancement under multi-spectral conditions, providing support for the metabolism of microorganisms.

[0013] In some embodiments, the sunlight introduction system (9) includes a Nephelitz lens, a filter, and light guiding optical fibers (5, 6, 7, 8). The light guiding optical fibers converge sunlight through the Nephelitz lens and transmit the external sunlight into the reactor. The filter is provided to adjust the spectral range to meet the requirements of different algal photosynthesis.

[0014] In some embodiments, the artificial light source includes LED lights (12, 13, 14), etc., which provide supplementary light when sunlight is insufficient.

[0015] In some embodiments, the monitoring system includes a pH probe (1), a dissolved oxygen probe (3), a redox potential probe (2), and a temperature probe (4). Multiple probes are installed inside the reactor to monitor the environmental changes inside the reactor in real time and feedback to the control system (16); through data feedback, the light source intensity, the temperature inside the reactor, and the stirring rate can be adjusted in a timely manner to ensure the best reaction conditions.

[0016] In some embodiments, the stirring system includes a mechanical stirring paddle (11) to ensure uniform distribution of the materials inside the reactor. The upper end of the stirring paddle (11) is connected to the control system (16), and its rotation speed stirring rate range is 300 - 700 r / min, regulated by an external driving device. The lower end of the stirring paddle is provided with blades to ensure sufficient contact between the algae and the light source during the reaction process, avoid efficiency losses caused by uneven light, enhance the mixing of substances inside the reactor, and improve the efficiency of photocatalysis and anaerobic biodegradation.

[0017] In some embodiments, the reactor main body can accommodate a culture solution volume of up to 500 L. The structure of the photo-anaerobic bioreactor ensures light uniformity, temperature control, sufficient mixing and flow of substances, thereby creating the best conditions for microorganism growth.

[0018] In some embodiments, a feed inlet (10) is provided at the top of the reactor body, and a discharge outlet (15) is provided at the bottom, facilitating the addition of materials and the collection of reaction products. The feeding and discharging system adopts a sealed design to ensure the stability of the photo-anaerobic environment inside the reactor.

[0019] In a second aspect, the present invention provides a method for enhancing methane production by methanogens in anaerobic digestion, comprising the following steps:

[0020] Step 1, algae cultivation: Cultivate cyanobacteria and green algae by controlling the cultivation conditions to promote the rapid growth of algae, and collect algal biomass.

[0021] Step 2, heat treatment of algal biomass: Centrifuge and separate to collect the part rich in photosensitive substances, and obtain algal organic matter as a photosensitive material through filtration, drying or concentration techniques.

[0022] Step 3, reaction environment construction: Add the algal organic matter to an anaerobic digestion reactor, mix it with anaerobic methanogenic microorganisms and a carbon-free medium, and control the temperature and pH inside the reactor to provide an optimized environment for the growth of methanogens.

[0023] Step 4, light enhancement: Promote the metabolic efficiency of methanogens by configuring and adjusting the lighting system.

[0024] In some embodiments, in Step 1, the cultivation conditions include, but are not limited to, light (100 - 500 μmol·m-2·s-1), temperature (22 - 37 °C, such as 30 - 37 °C), nutrients (nitrogen, phosphorus and trace elements), and pH (7.0 - 8.5). Appropriate nutrient solution is supplemented if necessary.

[0025] In some embodiments, in Step 2, the heat treatment includes: heating the algal biomass at 40 °C to 80 °C to break the algal cell wall and release intracellular active substances.

[0026] In some embodiments, in Step 3, the addition amount of the algal organic matter is 0.1% - 1% of the volume of the anaerobic digestion reactor.

[0027] In some embodiments, in Step 3, control the temperature range inside the reactor to be mesophilic 35 - 38 °C or thermophilic 50 - 55 °C; the pH range is 6.8 - 7.2 to provide an optimized environment for the growth of methanogens.

[0028] In some embodiments, in step 4, by configuring the lighting system, multi-spectral light energy is provided in the reaction environment to activate the photosensitive material of algal organic matter. The photosensitive material absorbs the light energy and converts it into chemical energy, further promoting the metabolic efficiency of methanogens. Preferably, the light intensity, photoperiod, and spectrum can be adjusted according to specific experimental requirements. For example, the light intensity ranges from 50 to 300 μmol·m-2·s-1, and the photoperiod is 12 hours of light / 12 hours of darkness.

[0029] Technical effects

[0030] By integrating the multi-spectral synergistic effect of sunlight and artificial light sources, and combining algal organic matter as a photosensitive material, the present invention effectively improves the light energy capture and conversion efficiency, and simultaneously optimizes the microbial metabolic pathway in the anaerobic digestion process.

[0031] The present invention uses algal organic matter as a photosensitive material, utilizes its photoactive components to enhance light energy capture and conversion, synergistically optimizes the metabolic pathway with anaerobic microorganisms, and significantly improves the light energy utilization efficiency and anaerobic digestion effect. Under light conditions, the algal photosensitive material absorbs light energy through its photoactive components such as carotenoids and chlorophyll, and converts the light energy into an energy form that can be utilized in the microbial metabolic process. The light capture ability of the algal material effectively increases the light absorption area, and at the same time, by reducing light energy loss, strengthens the utilization efficiency of light in the reactor. In addition, the algal material can also act synergistically with anaerobic microorganisms to regulate the metabolic environment in the reactor, further optimizing the light energy conversion and utilization process. By introducing the algal photosensitive material, the light energy capture and utilization efficiency in the anaerobic digestion process is significantly improved, the energy conversion efficiency and gas production rate of the reactor are increased. At the same time, the synergistic effect of the photosensitive material optimizes the microbial metabolic pathway, reduces the reaction time, and enhances the system stability. Compared with the traditional direct light irradiation method, this method reduces energy consumption, improves light energy utilization rate, has double economic and environmental benefits, and helps to expand the application scope and actual operation efficiency of anaerobic technology.

[0032] The present invention introduces light energy into the anaerobic digestion reactor, activates the activity of anaerobic microorganisms through light, thereby accelerating the degradation rate of organic pollutants and significantly increasing the methane production. The principle of introducing light energy into the anaerobic digestion system is based on the physiological characteristics of photosynthetic bacteria and other light-sensitive microorganisms. These microorganisms can carry out metabolic activities more effectively under light conditions, including the decomposition of organic matter and the conversion of energy. The light energy directly acts on the photoreceptors of the microorganisms, triggering and accelerating the biochemical reaction process, thereby increasing the decomposition rate of organic matter and the output of biogas (such as methane). Improving treatment efficiency: By introducing light energy, activating light-sensitive microorganisms, and accelerating the decomposition process of organic matter, the treatment efficiency of the entire anaerobic digestion system is improved.

[0033] Increasing methane production: The utilization of light energy promotes a faster rate of methane generation, increasing the total output of methane.

[0034] Reducing energy consumption and costs: By enhancing biological reactions using light energy, the energy consumption of traditional high-energy-consuming heating processes can be reduced, thereby lowering operating costs and improving the overall energy efficiency of the system.

[0035] The present invention combines sunlight with artificial light sources such as LED lights. Through this hybrid light source system, the controllability of light is enhanced, making the light more flexible and efficient. First, sunlight is efficiently concentrated through a Nephelitz lens placed in front of a filter, and then the concentrated light energy is effectively transmitted to the inside of the anaerobic digestion reactor using a light-conducting material. In addition, artificial light sources (such as LED lights) are used to artificially control the parameters of light to adapt to different environmental and microbial requirements. By combining sunlight and artificial light sources in an anaerobic digestion system, the use of natural sunlight significantly reduces energy consumption. Especially under sufficient sunlight conditions, the dependence on power-driven artificial light sources can be minimized. The complementary use of sunlight and artificial light sources ensures the continuity and stability of light under different environmental conditions, effectively compensating for their respective disadvantages, such as the instability of sunlight and the high cost of LEDs. This flexible light control mechanism improves the efficiency and reliability of the anaerobic digestion process and optimizes the performance of the overall system.

[0036] The present invention adopts a modular spectral regulation method, combined with customized artificial light source parameters, to achieve precise control of light intensity, spectral combination, and irradiation duration, thereby flexibly adjusting light conditions. Through the use of replaceable filters, flexible adjustment of the sunlight spectrum is achieved, enabling the system to adjust the optimal spectrum according to different environmental conditions and microbial requirements, improving the light energy utilization efficiency and anaerobic digestion effect. Secondly, the customized artificial light source parameters allow precise control of light conditions, further optimizing the growth and metabolic processes of microorganisms and enhancing the production of useful gases such as methane. These effects comprehensively improve the operational flexibility, energy efficiency, and economic benefits of the system. Description of the Drawings

[0037] Figure 1 is a front view structural schematic diagram of the photo-anaerobic bioreactor of Embodiment 1 of the present invention;

[0038] Figure 2 is a top view structural schematic diagram of the photo-anaerobic bioreactor of Embodiment 1 of the present invention;

[0039] Figure 3 is a data graph of enhanced methane generation under light conditions of algal organic matter in Embodiment 2 of the present invention;

[0040] Reference Signs:

[0041] 1: pH probe; 2: Redox potential probe; 3: Dissolved oxygen probe; 4: Temperature probe; 5, 6, 7, 8: Light guiding optical fibers; 9: Solar energy introduction system; 10: Feed inlet; 11: Agitator paddle; 12, 13, 14: LED light strips; 15: Discharge outlet; 16: Control system. Detailed implementation manners

[0042] The following introduces multiple preferred embodiments of the present invention with reference to the accompanying drawings of the specification, making its technical content clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0043] Embodiment 1:

[0044] A photo-anaerobic bioreactor, as Figure 1 and 2 shown, includes a transparent or semi-transparent reactor body, and is configured with a light source system, a photosensitive material system, a mechanical agitator paddle (11), a monitoring system and a control system. The light source system includes a solar energy introduction system and LED light strips (12, 13, 14), and the photosensitive material system includes algal organic matter.

[0045] The algal organic matter includes: organisms and their derivatives of cyanobacteria or green algae, including but not limited to pigments (such as chlorophyll, phycocyanin, phycoerythrin), exopolysaccharides, carotenoids and other metabolic active substances produced by algae during metabolism.

[0046] The solar energy introduction system (9) includes a filter and a Nephelitz lens, which are connected to the light guiding optical fibers (5, 6, 7, 8) to transmit external sunlight into the reactor. The setting of the filter can adjust the spectral range to meet the requirements of different algal photosynthesis.

[0047] The reactor body is provided with a pH probe (1), a dissolved oxygen probe (3), a redox potential probe (2), and a temperature probe (4). A variety of probes are installed in the reactor to monitor the environmental changes in the reactor in real time and feedback to the control system; through data feedback, the light source intensity, the temperature in the reactor and the stirring rate can be adjusted in time to ensure the best reaction conditions.

[0048] The reactor body can accommodate a culture solution volume of up to 500 L.

[0049] The reactor body is provided with a feed inlet (10) at the top and a discharge outlet (15) at the bottom, which is convenient for the addition of materials and the collection of reaction products.

[0050] Embodiment 2:

[0051] This embodiment provides a method for enhancing methane production by anaerobic digestion with green algae.

[0052] First, cultivate green algae by controlling environmental conditions. The specific conditions include using BBM medium, light intensity of 100 μmol·m-2·s-1, and temperature of 25 °C. After 72 hours of cultivation, the green algae rapidly proliferate and accumulate a large amount of photosensitive active substances such as chlorophyll and extracellular polysaccharides, providing rich photosensitive materials for subsequent reactions.

[0053] The collected green algae biomass needs to be further processed to prepare highly active algal organic matter photosensitive materials. The processing methods include heating the green algae suspension (60 °C) to break the cell wall and release the internal active components; then centrifuging to remove the liquid phase part and retaining the solid phase rich in photosensitive components; finally, concentrating the liquid phase through vacuum freeze-drying technology to prepare highly pure and highly active algal photosensitive materials. These materials have the ability to absorb light energy and convert it into chemical energy, which is the key to enhancing methane production in anaerobic digestion.

[0054] In the experiment, the prepared photosensitive materials were added to the anaerobic reactor at a certain ratio of the total reactor volume (compared with a 500 L volume, 0 mg, 2 mg, 4 mg, 8 mg, and 16 mg of photosensitive materials were added respectively). The reactor also included anaerobic methane-producing microorganisms (OD 600 = 0.2) and a carbon-free medium. The photosensitive materials were evenly distributed in the reaction medium by shaking, while the reactor temperature was controlled at 37 °C, the pH was maintained at 7.0, and the shaking speed was 120 rpm. This reaction environment ensured the activity of methanogens and provided conditions for the photosensitive materials to fully play their roles.

[0055] After starting the light source system of the reactor, the LED lamp provided light with a wavelength of 400 - 700 nm and a light intensity of 100 μmol·m-2·s-1. After absorbing light energy, the photosensitive materials converted it into active intermediate products, promoted the metabolic pathway of methanogens, and accelerated the conversion of substrates into methane. The light intensity range was 300 μmol·m-2·s-1, and the light cycle was 12 hours of light / 12 hours of darkness.

[0056] The control group did not start the light source system (dark-0 mg: no photosensitive material added; dark-16 mg: 16 mg of photosensitive material added), and methanogens were cultured under the same other conditions. After 7 days of cultivation, the cumulative methane production was measured.

[0057] The experimental results are as Figure 3 shown. It can be seen that the treatment group with the addition of photosensitive materials and enhanced by light had a 20% increase in cumulative methane production compared with the control group. This method provides an innovative solution for improving the efficiency of anaerobic digestion by optimizing green algae cultivation and the application of photosensitive materials.

[0058] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by those skilled in the art in this technical field based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should fall within the protection scope determined by the claims.

Claims

1. A photo-anaerobic bioreactor, comprising a transparent or translucent reactor body, and is equipped with a light source system, a photosensitive material system, a stirring system, a monitoring system and a control system; the light source system comprises a sunlight introduction system and an artificial light source, the sunlight introduction system introduces natural light into the reactor through a light-guiding optical fiber, and the photosensitive material system comprises algae organic matter.

2. The photo-anaerobic bioreactor according to claim 1, characterized in that: The algae organic matter is organisms and their derivatives obtained by culturing blue algae and green algae, and the derivatives include pigments, extracellular polysaccharides, carotenoids and other metabolically active substances produced by algae during metabolism.

3. The photo-anaerobic bioreactor according to claim 1, characterized in that: The sunlight introduction system comprises a Nefelds lens, a filter and a light-guiding optical fiber. The light-guiding optical fiber converges sunlight through the Nefelds lens, and the filter is used to adjust the spectral range.

4. The photo-anaerobic bioreactor according to claim 1, characterized in that: The artificial light source includes an LED light strip.

5. The photo-anaerobic bioreactor according to claim 1, characterized in that: The monitoring system includes a pH probe, a dissolved oxygen probe, a redox potential probe and a temperature probe.

6. The photo-anaerobic bioreactor according to claim 1, characterized in that: The stirring system comprises a stirring paddle, the upper end of which is connected to a control system and the rotation speed of which is regulated by an external driving device to stir the liquid inside the reactor at a speed of 300-700 r / min; a blade is arranged at the lower end of the stirring paddle.

7. A method for enhancing methanogen production by anaerobic digestion, comprising the following steps: Step 1: Algae Culture Cultivate blue algae and green algae by controlling culture conditions, adjusting light, temperature, nutrients and pH to promote rapid growth of algae, and collect algae biomass; Step 2: Algal biomass processing thermally treating the collected algae biomass by heating it at a temperature ranging from 40° C. to 80° C.; The fraction rich in photosensitizing substances is collected by centrifugal separation technology, and further purified by filtering, drying or concentration technology to obtain algae organic matter as photosensitizing material; Step 3: React environment construction Adding the algae organic matter into the photo-anaerobic bioreactor according to any one of claims 1 to 6, mixing with anaerobic methanogenic microorganisms and a carbon-free culture medium, controlling the temperature in the reactor at 35-38° C. or 50-55° C., and controlling the pH range at 6.8-7.2; Step 4: Light Enhancement A lighting system including a solar light introduction system and an artificial light source was configured, and the light intensity was adjusted to 50-300 μmol·m-2·s-1. A photoperiod of 12 hours of light / 12 hours of darkness was adopted to cultivate methanogens.

8. The method according to claim 7, characterized in that In step 1, the culture conditions include light intensity of 100-500 μmol·m-2·s-1, temperature of 30-37°C, pH 7.0-8.5, and addition of nitrogen and phosphorus sources to promote algae growth.

9. The method according to claim 7, characterized in that In step 2, the heat treatment lasts for 30-120 minutes and is combined with ultrasonic or mechanical crushing technology.

10. The method according to claim 7, characterized in that In step 3, the stirring system in the reactor is regulated by an external control system, and the stirring rate is 300-700 r / min.

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