System for strengthening anaerobic digestion of organic solid waste

Abstract

The invention relates to the technical field of resource recovery, and discloses a system for strengthening anaerobic digestion of organic solid waste. The system comprises a photovoltaic power generation device and a bypass device, the photovoltaic power generation device is used for converting light energy into electric energy; the bypass device is used for electrically strengthening the anaerobic digestion substrate in the first area in the anaerobic digestion reactor based on the electric energy and returning the strengthened anaerobic digestion substrate to the second area in the anaerobic digestion reactor; the height of the first area in the anaerobic digestion reactor is lower than a preset height; the height of the second area in the anaerobic digestion reactor is higher than a preset height. According to the invention, the electric energy generated by photovoltaic is used for enhancing the efficiency of methane production by anaerobic digestion of the organic solid waste, so that the application scene of photovoltaic power generation is widened, and meanwhile, the transformation of the main reactor is avoided and the voltage required for electrically enhancing anaerobic digestion is reduced through the bypass device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource recycling, and particularly relates to a system for enhancing anaerobic digestion of organic solid waste. BACKGROUND

[0002] With the continuous increase in the global production of organic solid waste (such as municipal sludge, agricultural waste, kitchen waste, etc.), efficient treatment and resource utilization of the organic solid waste have become an urgent environmental and energy problem to be solved. At present, the treatment technologies for organic solid waste mainly include landfill, incineration, aerobic composting and anaerobic digestion, etc. Among them, the anaerobic digestion technology can convert organic matter in the organic solid waste into biogas (mainly composed of methane) through microbial metabolism, realize energy recovery and solid waste reduction, and reduce greenhouse gas emissions. The traditional anaerobic digestion technology has significant defects, mainly manifested in long fermentation period, low organic matter degradation rate, limited biogas yield, resulting in low treatment efficiency and insufficient resource utilization. Therefore, how to promote the decomposition and metabolism of organic solid waste and the generation of methane in the anaerobic digestion process, and improve the energy recovery rate of organic solid waste is the focus of attention at present. SUMMARY

[0003] Therefore, the present application provides a system for enhancing anaerobic digestion of organic solid waste to promote the decomposition and metabolism of organic solid waste and the generation of methane, and improve the energy recovery rate of organic solid waste.

[0004] The present application provides a system for enhancing anaerobic digestion of organic solid waste, which comprises: a photovoltaic power generation device and a bypass device.

[0005] The photovoltaic power generation device is used for converting light energy into electric energy.

[0006] The bypass device is used for electrically enhancing the anaerobic digestion substrate in the first region of the anaerobic digestion reactor based on the electric energy, and returning the enhanced anaerobic digestion substrate to the second region in the anaerobic digestion reactor; the height of the first region in the anaerobic digestion reactor is lower than a preset height; the height of the second region in the anaerobic digestion reactor is higher than the preset height.

[0007] The system provided by the embodiment can convert light energy into electric energy through the photovoltaic power generation device to provide power for the bypass device, and realize energy self-sufficiency of the electrically enhanced anaerobic digestion process. Compared with the electrically enhanced technology in the related art which relies on external power grid for power supply, the system provided by the embodiment significantly reduces the operation cost. Meanwhile, the bypass device is separated from the anaerobic digestion reactor instead of modifying the anaerobic digestion reactor, which further reduces the electrically enhanced cost. The embodiment combines the photovoltaic power generation device with the bypass device, and overcomes the problem that the electrically enhanced anaerobic digestion in the related art has a problem that the electric energy input is greater than the methane output. On the other hand, the bottom (the first region) of the anaerobic digestion reactor is usually rich in high-concentration organic matter and microorganisms, the substrate at the bottom of the first region of the anaerobic digestion reactor is electrically enhanced to promote the decomposition of organic matter and the metabolism of methanogenic bacteria, and then the enhanced substrate is returned to the upper part (the second region) of the reactor. The circulation mode forms a concentration gradient and an electron transfer gradient, enhances the material transfer and biological metabolism efficiency in the reactor, promotes the decomposition and metabolism of organic solid waste and the generation of methane, and improves the energy recovery rate of the organic solid waste.

[0008] In an optional embodiment, the bypass device comprises an ultrasonic module, the ultrasonic module being configured to disperse the anaerobic digestion substrate and microorganisms in the anaerobic digestion reactor, and the ultrasonic module being configured to be started when the input voltage of the bypass device is lower than a preset voltage.

[0009] In the embodiment, the ultrasonic stimulation can promote the cell membrane permeability of microorganisms, enhance the enzyme activity, and significantly improve the metabolic activity of methanogenic bacteria. Meanwhile, the ultrasonic module can effectively break the agglomerates (such as cellulose bundles and organic particles) in the anaerobic digestion substrate through the cavitation effect generated by high-frequency vibration, increase the contact area between microorganisms and organic matter, and improve the hydrolysis efficiency. In the low-voltage condition, the electrically enhanced effect of the bypass device is weakened. When the input voltage of the bypass device is lower than the preset voltage, for example, the electric energy is reduced due to weak light in the photovoltaic power generation device, the ultrasonic module can compensate for the insufficient electrically enhanced effect to ensure the stability of the anaerobic digestion process.

[0010] In an optional embodiment, the ultrasonic power and duration of the ultrasonic module have a positive correlation with the solid content in the anaerobic digestion reactor.

[0011] In the above-mentioned embodiments, when the solid content in the anaerobic digestion reactor is high, the viscosity of the anaerobic digestion substrate increases, and the mass transfer resistance increases. Therefore, the processing efficiency can be improved by increasing the ultrasonic power of the ultrasonic module and prolonging the action time.

[0012] In an optional embodiment, the bypass device comprises an electrode module, a cathode in the electrode module is arranged on the inner wall of the bypass device, and an anode in the electrode module is arranged in the center of the bypass device.

[0013] Through the above-mentioned embodiments, the electrons generated by the anode migrate to the cathode through the anaerobic digestion substrate, the layout of the central anode and the inner wall cathode makes the electron transfer path shorter and more uniform, reduces the electrical resistance, and reduces the electrical energy loss. In addition, the cathode is arranged on the inner wall of the bypass device, and the anode is arranged in the center of the bypass device. This similar cylindrical symmetric structure forms a radial uniform electric field, so that the entire substrate cross section is within the effective electric field range, promoting direct electron transfer between microorganisms and electrodes. Furthermore, the high concentration of organic matter environment around the central anode helps to form an efficient electron transfer biofilm, and the cathode located on the inner wall can provide a larger surface area, promote the attachment of methanogens to generate, accelerate the process of reducing carbon dioxide to methane, and help to improve the methanogenesis efficiency.

[0014] In an alternative embodiment, the system further comprises: an energy storage device, the energy storage device being connected to the photovoltaic power generation device;

[0015] The energy storage device is used to store the electrical energy converted by the photovoltaic power generation device.

[0016] Through the above-mentioned embodiments, the energy storage device can store the excess electrical energy generated by the photovoltaic power generation device under sufficient light, and release electrical energy under insufficient light, such as at night or on rainy days, to ensure that the electrically enhanced process of the bypass device can be continuously operated, avoiding the electrical energy fluctuations caused by the photovoltaic power generation device directly outputting electrical energy to the bypass device, and ensuring the stable operation of the system.

[0017] In an alternative embodiment, the system further comprises: a voltage conversion device, the energy storage device being connected to the bypass device through the voltage conversion device;

[0018] The voltage conversion device is used to receive the output voltage of the energy storage device, adjust the output voltage of the energy storage device to obtain an adjusted voltage, and input the adjusted voltage to the bypass device.

[0019] Through the above-mentioned embodiments, the voltage conversion device converts the output voltage of the energy storage device into the working voltage required by the bypass device, so that the electrically enhanced voltage of the electrically enhanced process is accurately adjusted.

[0020] In an alternative embodiment, the residence time of the anaerobic digestion substrate in the bypass device is determined based on the volume of the bypass device, the volume of the anaerobic digestion reactor, and the residence time of the corresponding organic solid waste in the anaerobic digestion reactor.

[0021] Through the above implementation method, the residence time of the anaerobic digestion substrate in the bypass device is determined based on the residence time of the organic solid waste corresponding to the anaerobic digestion substrate in the anaerobic digestion reactor, the volume of the bypass device, and the volume of the anaerobic digestion reactor. This design synchronizes the bypass enhancement process with the microbial metabolic cycle of the main reactor, avoiding insufficient electro-enhancement due to too short a residence time in the bypass device, or energy waste due to too long a residence time.

[0022] In one optional implementation, the formula for calculating the residence time of the anaerobic digestion substrate in the bypass device includes:

[0023]

[0024] Among them, T 旁 V represents the residence time of the anaerobic digestion substrate in the bypass device. 旁 V is the volume of the bypass device; 主 T is the volume of the anaerobic digester reactor. 主 is the residence time of the organic solid waste corresponding to the anaerobic digestion substrate in the anaerobic digestion reactor; k is the minimum ratio of the anaerobic digestion substrate in the bypass device to the anaerobic digestion substrate in the anaerobic digestion reactor.

[0025] In order to ensure the enhancement effect of the entire anaerobic digestion through the above implementation method, it is necessary to electrically enhance at least the minimum proportion k of the material in the anaerobic digestion reactor to enhance its adaptability to the complex matrix in the anaerobic digestion reactor.

[0026] In one alternative implementation, the distance between the cathode and the anode is determined by a preset mass and a preset resistance; the preset mass is the minimum mass of the anaerobic digestion substrate that the bypass device can enhance; and the preset resistance is the maximum resistance between the cathode and the anode.

[0027] In the above implementation, the cathode is located on the inner wall of the bypass device, and the anode is located in the center of the bypass device. The distance between the cathode and anode is the inner diameter (radius) of the bypass device. When the distance between the cathode and anode is less than a certain distance (e.g., 20 cm), the mass of anaerobic digestion substrate that can be enhanced per unit height of the bypass device is relatively limited, which is not technically economical. Although the greater the distance between the electrodes, the more anaerobic digestion substrate that can be enhanced per unit height of the bypass device, and the better the economic efficiency, when the distance between the cathode and anode is too large (e.g., exceeding 80 cm), it will lead to excessive resistance, affecting the electro-enhancement effect. Therefore, in this implementation, the distance between the cathode and anode is determined based on the minimum mass of anaerobic digestion substrate that the bypass device can enhance and the maximum resistance between the cathode and anode, ensuring the electro-enhancement efficiency while improving the substrate enhancement quality of the bypass device.

[0028] In an alternative embodiment, the voltage adjusting device is further configured to determine the adjusted voltage based on the activity of the microorganisms in the anaerobic digestion substrate.

[0029] With the above embodiments, within a certain voltage range, the activity of the microorganisms in the anaerobic digestion substrate is activated, but excessive voltage can cause the cells of the microorganisms to rupture, affecting the activity of the microorganisms. Therefore, the adjusted voltage can be determined based on the activity of the microorganisms in the anaerobic digestion substrate, so that the voltage of the enhanced anaerobic digestion substrate is within a reasonable voltage range, the activity of the microorganisms in the anaerobic digestion substrate is activated, and the enhancement effect is improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the specific embodiments or prior art of the present application, the drawings needed in the specific embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0031] Figure 1 is a structural schematic diagram of a system for enhancing anaerobic digestion of organic solid waste according to an embodiment of the present application;

[0032] Figure 2 is a structural schematic diagram of another system for enhancing anaerobic digestion of organic solid waste according to an embodiment of the present application. DETAILED DESCRIPTION

[0033] The technical solutions of the present application will be described below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0034] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0035] First, the application scenario of the embodiments of the present application is exemplarily introduced.

[0036] With the acceleration of global urbanization, the demand for large-scale treatment of organic solid waste (such as municipal sludge, agricultural waste, kitchen waste, etc.) is increasingly urgent. Among the treatment technologies of organic solid waste, anaerobic digestion has become the mainstream technology direction due to its organic solid waste reduction, energy (biogas production) and low carbon emission characteristics. This treatment technology converts organic matter into methane (CH4) and carbon dioxide (CO2) through microbial metabolic activity, while realizing the resource utilization of solid waste, it can reduce environmental pollution and greenhouse gas emissions caused by landfill or incineration. Therefore, how to promote the decomposition and metabolism of organic solid waste and methane generation in the anaerobic digestion process, and improve the energy recovery rate of organic solid waste is the focus of attention.

[0037] Therefore, the embodiment of the present application provides a system for strengthening anaerobic digestion of organic solid waste to promote the decomposition and metabolism of organic solid waste and methane generation in the anaerobic digestion process, and improve the energy recovery rate of organic solid waste.

[0038] In the embodiment, a system for strengthening anaerobic digestion of organic solid waste is provided, Figure 1 is a structural schematic diagram of a system for strengthening anaerobic digestion of organic solid waste according to the embodiment of the present application, as Figure 1 shown, the system comprises: a photovoltaic power generation device 1 and a bypass device 2.

[0039] The photovoltaic power generation device 1 is used to convert light energy into electrical energy.

[0040] In a possible implementation, the photovoltaic power generation device 1 is a device that converts solar radiation energy directly into electrical energy by using the photovoltaic effect, and the core component is a solar cell panel (such as single crystal silicon, polycrystalline silicon or thin film battery). It usually includes photovoltaic components, combiner boxes, inverters and other supporting equipment.

[0041] It should be noted that in the case where the electrical energy generated by the photovoltaic power generation device 1 is less than the preset electrical energy, an external power source can be used to provide electrical energy for the bypass device 2.

[0042] The bypass device 2 is used to electrically strengthen the anaerobic digestion substrate in the first area of the anaerobic digestion reactor based on electrical energy, and return the strengthened anaerobic digestion substrate to the second area in the anaerobic digestion reactor; the height of the first area in the anaerobic digestion reactor is lower than the preset height; the height of the second area in the anaerobic digestion reactor is higher than the preset height.

[0043] In a possible implementation, the anaerobic digestion reactor is used for anaerobic digestion of the input organic solid waste. In the embodiments of the present application, the first region is the bottom region of the anaerobic digestion reactor, which is rich in high-concentration organic solid waste and hydrolysis and fermentation bacteria, and has a high solid content of the substrate. For example, the first region is the lower 1 / 4 of the height of the anaerobic digestion reactor. The second region is the top region of the anaerobic digestion reactor, which is mainly liquid substrate and rich in methanogenic bacteria, and is the main region of biogas production. For example, the first region is the upper 1 / 4 of the height of the anaerobic digestion reactor. The preset height can be set according to the specific results of the anaerobic digestion reactor, or according to the fluid mechanics characteristics, which is not limited in the present application.

[0044] Optionally, the anaerobic digestion reactor can be a complete-mix anaerobic reactor. The solid content of the reactor is set in the range of [85%, 95%]. In this solid content range, neither the high concentration of organic matter will cause too large resistance to limit the electron transfer process, nor the low concentration of organic matter will cause long reaction time of the anaerobic digestion system and reduce the economy.

[0045] In a possible implementation, the electric enhancement refers to a technical means for promoting microbial electron transfer by an external electric field, for accelerating the decomposition of organic matter into acetic acid, hydrogen and other methanogenic precursors, improving the activity of methanogenic bacteria, and shortening the digestion period. The bypass device 2 is used for diverting part of the anaerobic digestion substrate from the anaerobic digestion reactor to the in-vitro enhanced treatment cycle unit, improving the microbial activity and the degradation efficiency of organic matter in the anaerobic digestion substrate by electric enhancement (such as electrode effect), and then returning the enhanced anaerobic digestion substrate to the anaerobic digestion reactor to form a treatment cycle. For example, the bypass device 2 can realize the circulation of the anaerobic digestion substrate between the first region and the second region through a circulating pump module.

[0046] In a possible implementation, the bypass device 2 includes but is not limited to an electrode module, a circulating pump module, a detection instrument, and the like. The electrode module is used to build an electric field environment for electric enhancement of the anaerobic digestion substrate. The circulating pump module is used to drive the flow of the anaerobic digestion substrate between the bypass device 2 and the anaerobic digestion reactor. The monitoring instrument is used to detect pH value, conductivity and the like, and to collect the state of the anaerobic digestion substrate in real time.

[0047] The system in the embodiments of the present application, on the one hand, converts light energy into electric energy through the photovoltaic power generation device 1 to provide power for the bypass device 2, and realizes energy self-sufficiency of the electrically enhanced anaerobic digestion process. Compared with the electrically enhanced technology in the related art which relies on external power grid for power supply, the system provided in the embodiments significantly reduces the operation cost. At the same time, the bypass device 2 is separated from the anaerobic digestion reactor instead of modifying the anaerobic digestion reactor, which further reduces the electrically enhanced cost. The embodiments combine the photovoltaic power generation device 1 with the bypass device 2, and overcome the problem that the electrically enhanced anaerobic digestion in the related art has a problem that the electric energy input is greater than the methane output. On the other hand, the bottom (the first region) of the anaerobic digestion reactor is usually rich in high-concentration organic matter and microorganisms, the substrate at the bottom in the first region of the anaerobic digestion reactor is electrically enhanced, organic matter decomposition and methanogen metabolism are promoted, and then the enhanced substrate is returned to the upper part (the second region) of the reactor. This cycle forms a concentration gradient and an electron transfer gradient, enhances the material transfer and biological metabolism efficiency in the reactor, promotes the decomposition and metabolism of organic solid waste and the generation of methane, and improves the energy recovery rate of the organic solid waste.

[0048] In some embodiments, the bypass device 2 comprises an ultrasonic module, the ultrasonic module being configured to disperse the anaerobic digestion substrate and microorganisms in the anaerobic digestion reactor.

[0049] In a possible implementation, the ultrasonic module is a device that uses the physical effects (such as cavitation, mechanical vibration) of ultrasonic waves (frequency > 20 kHz) to enhance the anaerobic digestion process. Ultrasonic stimulation can promote microbial cell membrane permeability, enhance enzyme activity, and significantly improve the metabolic activity of methanogens. At the same time, the ultrasonic module effectively breaks up the aggregates (such as cellulose bundles, organic particles) in the anaerobic digestion substrate through the cavitation effect generated by high-frequency vibration, increases the contact area between microorganisms and organic matter, and improves the hydrolysis efficiency.

[0050] In a possible implementation, the ultrasonic module is started when the input voltage of the bypass device 2 is lower than a preset voltage.

[0051] This is because, under low-voltage conditions, the electrically enhanced effect of the bypass device 2 will be weakened. In the case where the input voltage of the bypass device 2 is lower than the preset voltage, such as the decrease in electric energy caused by weak light conditions of the photovoltaic power generation device 1, the ultrasonic module is added to the bypass device 2 to compensate for the insufficient electrically enhanced effect, and to ensure the stability of the anaerobic digestion process. The system in the embodiments of the present application adopts the combination of the electrode module and the ultrasonic module to synergistically enhance the anaerobic digestion substrate in the bypass device 2, and the enhancement efficiency of organic matter degradation and methane production rate is further improved compared with a single enhancement mode. Compared with directly enhancing in the anaerobic digestion reactor (also referred to as the main reactor), the bypass device separated from the anaerobic digestion reactor greatly reduces the requirements for voltage and ultrasonic power, and can greatly reduce the investment and operation cost.

[0052] In a possible implementation, the ultrasonic power and the duration of the ultrasonic module are positively correlated with the solid content in the anaerobic digestion reactor.

[0053] Optionally, the ultrasonic power refers to the energy output by the ultrasonic module per unit time, reflecting the intensity of the ultrasonic wave. The duration refers to the working time of the ultrasonic module. The solid content refers to the mass percentage of solid substances in the anaerobic digestion substrate. The higher the solid content in the anaerobic digestion reactor, the larger and more difficult to decompose the solid particles in the anaerobic digestion substrate, requiring stronger ultrasonic power and longer processing time. Conversely, the lower the solid content, the fewer particles in the anaerobic digestion substrate, and the easier to decompose, at which time, low-power and short-time ultrasonic waves can achieve the function of the ultrasonic module, avoiding energy waste.

[0054] It should be noted that when the ultrasonic power and the duration are too large, the microbial cells are damaged, and when the ultrasonic power and the duration are too small, the dispersion effect is poor. By setting appropriate ultrasonic power and duration, the electrical enhancement efficiency of the ultrasonic module can be improved. For example, the ultrasonic power ranges from [0.5 kW / m 3 , 5 kW / m 3 ], and the duration ranges from [30 s / h, 150 s / h]. In this way, the ultrasonic wave acts on the dispersion of organic matter and microorganisms, making the anaerobic digestion substrate more uniform, and thus improving the efficiency of electrical enhancement.

[0055] In some embodiments, the bypass device 2 includes an electrode module, a cathode in the electrode module is arranged on the inner wall of the bypass device 2, and an anode in the electrode module is arranged in the center of the bypass device 2.

[0056] In a possible implementation, the electrode module is used to build an electric field environment for electrical enhancement, promote the electron transfer of microorganisms in the anaerobic digestion substrate, and accelerate the generation of organic matter and methane. The anode in the electrode module serves as an electrode that releases electrons in the electrode module, and the cathode serves as an electrode that accepts electrons in the electrode module. The material of the anode needs to have high electron conductivity, corrosion resistance, and biocompatibility, etc., and for example, can be a stainless steel mesh, a carbon felt, a platinum-coated titanium electrode, etc. The material of the cathode needs to have oxidation resistance and high electron transport efficiency, and for example, can be a carbon brush, a titanium-based oxide electrode, etc.

[0057] In a possible implementation, the distance between the cathode and the anode is determined by a preset mass and a preset resistance. The preset mass is the minimum mass of the anaerobic digestion substrate that can be enhanced by the bypass device 2, and the preset resistance is the maximum resistance between the cathode and the anode.

[0058] Optionally, the distance between the cathode and the anode is a core parameter of the electrode layout of the bypass device 2, which directly affects the resistance, electric field distribution and microbial metabolic efficiency.

[0059] Optionally, the preset mass is the minimum mass of anaerobic digestion substrate that the bypass device 2 can effectively process under design conditions. The preset resistance is the maximum resistance between the cathode and anode. If the resistance between the cathode and anode exceeds this preset resistance, the energy loss will increase significantly, resulting in a decrease in energy efficiency. The preset mass and preset resistance can be set according to the actual engineering requirements of the bypass device 2.

[0060] For example, constraint equations are established based on minimum mass and maximum resistance to obtain the distance between the cathode and anode, calculated as follows:

[0061]

[0062] Where L is the distance between the cathode and the anode, ρ is the resistivity of the anaerobic digestion substrate, and ρ 密 R is the density of the anaerobic digestion substrate. max The maximum resistance is given by S, where S is the area of ​​the electrodes facing each other, i.e., the area between the cathode and anode, in meters. min It is the minimum mass.

[0063] For example, when R max For 100Ω, R max It is 100kg, ρ is 50Ω·m, ρ 密 1000 kg / m 3 S is 0.5m 2 At this time, the distance between the cathode and the anode needs to be between 0.2 and 1.0 m. An example of choosing 0.5 m is to satisfy the requirement that the resistance does not exceed 100 Ω and can accommodate at least 100 kg of substrate.

[0064] The distance between the cathode and the anode is the inner diameter (radius) of the bypass device 2. When the distance between the cathode and the anode is less than a certain distance (for example, 20 cm), the mass of the anaerobic digestion substrate that can be strengthened by the bypass device 2 per unit height is relatively limited, and it is not technically and economically feasible. Although the greater the distance between the cathode and the anode, the greater the mass of the anaerobic digestion substrate that can be strengthened by the bypass device 2 per unit height, and the better the economy, when the distance between the cathode and the anode is too large (for example, more than 80 cm), it will lead to too large resistance, affecting the electric strengthening effect. Therefore, in the embodiment, the distance between the cathode and the anode is determined based on the minimum mass of the anaerobic digestion substrate that can be strengthened by the bypass device 2 and the maximum resistance between the cathode and the anode, which ensures the electric strengthening efficiency while improving the mass of the substrate that can be strengthened by the bypass device 2. In the embodiment, the distance between the cathode and the anode is in the range of [20 cm, 80 cm].

[0065] In the embodiment, the electrons generated by the anode migrate to the cathode through the anaerobic digestion substrate, and the layout of the central anode and the inner wall cathode makes the electron transfer path shorter and more uniform, reduces the resistance, and reduces the power loss. In addition, the cathode is arranged on the inner wall of the bypass device 2, and the anode is arranged in the center of the bypass device 2, which forms a radial uniform electric field in a cylindrical symmetric structure, so that the entire substrate cross section is within the effective electric field range, promoting direct electron transfer between microorganisms and electrodes. Furthermore, the high-concentration organic environment around the central anode helps to form an efficient electron transfer biofilm, and the cathode on the inner wall can provide a larger surface area, promote the attachment of methanogens, accelerate the process of reducing carbon dioxide to methane, and help to improve the methanogenesis efficiency.

[0066] In some embodiments, considering that the power generation of the photovoltaic power generation device 1 is affected by factors such as light intensity, weather, and seasonal changes, the electric energy generated by the photovoltaic power generation device 1 is intermittent and fluctuating. Therefore, the system provided in the embodiment further comprises a storage device 3 connected to the photovoltaic power generation device 1.

[0067] The storage device 3 is used to store the electric energy converted by the photovoltaic power generation device 1.

[0068] In the embodiment, the storage device 3 can store the excess electric energy generated by the photovoltaic power generation device 1 when the light is sufficient, and release the electric energy when the light is insufficient, such as at night or on rainy days, to ensure that the electric strengthening process of the bypass device 2 can be continuously operated, avoiding the fluctuation of the electric energy caused by the direct output of the electric energy from the photovoltaic power generation device 1 to the bypass device 2, and ensuring the stable operation of the system.

[0069] In some embodiments, the system provided by the embodiments of the present application further comprises a voltage conversion device 4, and the energy storage device 3 is connected to the bypass device 2 through the voltage conversion device 4.

[0070] The voltage conversion device 4 is configured to receive an output voltage of the energy storage device 3, adjust the output voltage of the energy storage device 3 to obtain an adjusted voltage, and input the adjusted voltage to the bypass device 2. In the embodiments of the present application, the voltage conversion device 4 converts the output voltage of the energy storage device 3 into a direct-current working voltage required by the bypass device 2, so that the electric field strengthening voltage of the electric field strengthening process is accurately adjusted.

[0071] In a possible implementation, when the bypass device 2 comprises an electrode module, the voltage conversion device 4 converts the output voltage of the energy storage device 3 into a working voltage (also referred to as a first voltage) required by the electrode module. When the bypass device 2 comprises an ultrasonic module, the voltage conversion device 4 converts the output voltage of the energy storage device 3 into a working voltage (also referred to as a second voltage) required by the ultrasonic module.

[0072] In a possible implementation, when the bypass device 2 comprises both the electrode module and the ultrasonic module, the voltage conversion device 4 converts the output voltage of the energy storage device 3 into the working voltage required by the electrode module and the working voltage required by the ultrasonic module, respectively. In this way, the voltage conversion device 4 converts based on the actual required working voltage in the bypass device 2 to support the normal work of the bypass device 2.

[0073] In a possible implementation, the voltage conversion device 4 is further configured to determine the adjusted voltage based on the activity of the microorganism in the anaerobic digestion substrate. This is because, within a certain voltage range, the activity of the microorganism in the anaerobic digestion substrate is activated, but an excessively large voltage can cause the cells of the microorganism to rupture, affecting the activity of the microorganism. Therefore, the adjusted voltage can be determined based on the activity of the microorganism in the anaerobic digestion substrate, so that the voltage for strengthening the anaerobic digestion substrate is within a reasonable voltage range, the activity of the microorganism in the anaerobic digestion substrate is activated, and the strengthening effect is improved.

[0074] Optionally, the activity of the microorganism in the anaerobic digestion substrate can be represented by indexes such as enzyme activity, metabolic rate, and cell activity. The above indexes can be obtained by sensors and the like.

[0075] Optionally, the adjusted voltage is within the range of [0.1V, 18V].

[0076] Preferably, the adjusted voltage is within the range of [0.2V, 12V]. Within this range, the activity of the microorganism can be activated to promote direct electron transfer, and the cells of the microorganism will not rupture to affect the activity of the microorganism.

[0077] Optionally, the energization duration of the voltage transformation device 4 is not limited, for example, the energization duration of the voltage transformation device 4 is consistent with the duration of the photovoltaic power generation device 1.

[0078] In some embodiments, the residence time of the anaerobic digestion substrate in the bypass device 2 is determined based on the volume of the bypass device 2, the volume of the anaerobic digestion reactor, and the residence time of the organic solid waste corresponding to the anaerobic digestion substrate in the anaerobic digestion reactor.

[0079] In this way, the residence time of the anaerobic digestion substrate in the bypass device 2 is determined based on the residence time of the organic solid waste corresponding to the anaerobic digestion substrate in the anaerobic digestion reactor, the volume of the bypass device 2, and the volume of the anaerobic digestion reactor, so that the bypass intensification process is synchronized with the microbial metabolic cycle of the main reactor, avoiding insufficient electric intensification due to too short residence time of the bypass device 2, or energy waste due to too long residence time of the bypass device 2.

[0080] In one possible implementation, the calculation formula of the residence time of the anaerobic digestion substrate in the bypass device 2 includes:

[0081]

[0082] wherein T 旁 is the residence time of the anaerobic digestion substrate in the bypass device 2; V 旁 is the volume of the bypass device 2; V 主 is the volume of the anaerobic digestion reactor; T 主 is the residence time of the organic solid waste corresponding to the anaerobic digestion substrate in the anaerobic digestion reactor; and k is the minimum proportion of the anaerobic digestion substrate in the bypass device 2 to the anaerobic digestion substrate in the anaerobic digestion reactor.

[0083] In the embodiments of the present application, in order to ensure the intensification effect of the entire anaerobic digestion, at least the material with the minimum proportion k in the anaerobic digestion reactor needs to be electrically intensified to enhance the adaptability to the complex substrate in the anaerobic digestion reactor.

[0084] For example, k is set to 10%, and the residence time of the anaerobic digestion substrate in the bypass device 2 is in the range of 3h to 24h.

[0085] This is because the minimum residence time is set to 3h, and below this duration, the anaerobic digestion substrate in the bypass device 2 is difficult to be sufficiently intensified. In addition, in order to ensure the intensification effect of the entire anaerobic digestion, at least 10% of the anaerobic digestion substrate in the anaerobic digestion reactor needs to be electrically intensified, that is, k is 10%, and thus the maximum residence time of the substrate in the bypass device 2 can be calculated as 24h. It should be noted that in order to ensure the feasibility of the system, when designing the bypass device 2, it is necessary to ensure that

[0086] In addition, the residence time of the anaerobic digestion substrate in the bypass device 2 is also related to the input voltage of the bypass device 2, the solid content of the anaerobic digestion substrate in the bypass device 2, and the distance between the cathode and the anode in the electrode module of the bypass device 2. The bypass device 2 in the system provided by the embodiments of the present application is also used to determine the residence time of the anaerobic digestion substrate in the bypass device 2 based on one or more of the input voltage of the bypass device 2, the solid content of the anaerobic digestion substrate in the bypass device 2, and the distance between the cathode and the anode in the electrode module of the bypass device 2.

[0087] For example, the input voltage of the bypass device 2 is negatively correlated with the residence time of the anaerobic digestion substrate in the bypass device 2, that is, the greater the input voltage of the bypass device 2, the shorter the residence time of the anaerobic digestion substrate in the bypass device 2.

[0088] For example, the solid content of the anaerobic digestion substrate in the bypass device 2 is positively correlated with the residence time of the anaerobic digestion substrate in the bypass device 2, that is, the higher the solid content (the greater the resistance), the longer the residence time of the anaerobic digestion substrate in the bypass device 2.

[0089] For example, the distance between the cathode and the anode in the electrode module of the bypass device 2 is positively correlated with the residence time of the anaerobic digestion substrate in the bypass device 2, that is, the greater the distance between the cathode and the anode in the electrode module (the greater the resistance), the longer the residence time of the anaerobic digestion substrate in the bypass device 2.

[0090] Figure 2 A structural schematic diagram of a system for enhancing anaerobic digestion of organic solid waste. In the system, a photovoltaic power generation device, an energy storage device, a voltage conversion device, and a bypass device (including an electrode module and an ultrasonic module) are connected in sequence. The voltage conversion device adjusts the output voltage of the energy storage device to obtain an adjusted voltage (a first voltage and a second voltage). The first voltage is used to support the operation of the electrode module, and the second voltage is used to support the operation of the ultrasonic module. The cathode in the electrode module is arranged on the inner wall of the bypass device, and the anode in the electrode module is arranged in the center of the bypass device. A central complete-mixing anaerobic digestion (main) reactor is connected to the bypass device in the system. The process of electrically enhancing the complete-mixing anaerobic digestion (main) reactor in the system for enhancing anaerobic digestion of organic solid waste includes: first, inputting pretreated organic solid waste into the complete-mixing anaerobic digestion (main) reactor. During the anaerobic digestion reaction in the complete-mixing anaerobic digestion (main) reactor, gas products, as well as solid and liquid products, are contained. The complete-mixing anaerobic digestion (main) reactor outputs the anaerobic digestion substrate located at the bottom to the bypass device. After being electrically enhanced by the electrode module and the ultrasonic module in the bypass device, the anaerobic digestion substrate is obtained. The bypass device returns the enhanced anaerobic digestion substrate to the top of the complete-mixing anaerobic digestion (main) reactor.

[0091] By the system in the embodiments of the present application, on the one hand, the organic matter degradation rate and the methane yield of the organic solid waste anaerobic digestion are increased by more than 20% through the bypass device to strengthen the anaerobic digestion reaction, the treatment capacity (cost) of the biogas residue is reduced, and the resource product quantity (added value) is increased, thereby reducing the comprehensive cost and carbon emission level of the organic solid waste disposal and resource utilization. On the other hand, the micro-voltage and ultrasonic two ways are used to cooperatively strengthen the substrate in the bypass device, compared with a single strengthening method, the strengthening efficiency of the organic matter degradation and the methane yield is further improved; compared with directly strengthening in the anaerobic digestion reactor, the requirement of voltage and ultrasonic power is greatly reduced, and the investment and operation cost can be greatly reduced. On the other hand, the power consumption of the electrode module and the ultrasonic module is basically matched with the photovoltaic power generation power, the electric energy generated by the photovoltaic is fully utilized, and energy waste is avoided; except that a small amount of power consumption is generated during the transportation of the substrate between the bypass device and the anaerobic digestion reactor, the system provided in the embodiments of the present application does not increase other operation costs.

[0092] It should be noted that in this document, the terms "comprise", "comprise", or any other variant thereof are intended to cover non-exclusive inclusion, so that processes, methods, articles or devices that include a series of elements not only include those elements, but also include other elements not explicitly listed, or include elements inherent to such processes, methods, articles or devices. Without more limitations, the element defined by the statement "comprises a" does not exclude the presence of additional identical elements in the process, method, article or device that includes the element.

[0093] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications of these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A system for enhancing the anaerobic digestion of organic solid waste, characterized in that, The system includes: a photovoltaic power generation device and a bypass device; The photovoltaic power generation device is used to convert light energy into electrical energy; The bypass device is used to electrically enhance the anaerobic digestion substrate in the first region of the anaerobic digestion reactor based on the electrical energy, and return the enhanced anaerobic digestion substrate to the second region of the anaerobic digestion reactor; the first region is at a height lower than a preset height in the anaerobic digestion reactor; the second region is at a height higher than the preset height in the anaerobic digestion reactor.

2. The system according to claim 1, characterized in that, The bypass device includes an ultrasonic module, which is used to disperse the anaerobic digestion substrate and microorganisms in the anaerobic digestion reactor; the ultrasonic module is activated when the input voltage of the bypass device is lower than a preset voltage.

3. The system according to claim 2, characterized in that, The ultrasonic power and duration of the ultrasonic module are positively correlated with the solids content in the anaerobic digester.

4. The system according to any one of claims 1-3, characterized in that, The bypass device includes an electrode module, wherein the cathode of the electrode module is disposed on the inner wall of the bypass device; and the anode of the electrode module is disposed in the center of the bypass device.

5. The system according to claim 1, characterized in that, The system further includes an energy storage device, which is connected to the photovoltaic power generation device; The energy storage device is used to store the electrical energy converted by the photovoltaic power generation device.

6. The system according to claim 5, characterized in that, The system further includes: a transformer, through which the energy storage device is connected to the bypass device; The transformer is used to receive the output voltage of the energy storage device; adjust the output voltage of the energy storage device to obtain an adjusted voltage; and input the adjusted voltage to the bypass device.

7. The system according to claim 1, characterized in that, The residence time of the anaerobic digestion substrate in the bypass device is determined based on the volume of the bypass device, the volume of the anaerobic digestion reactor, and the residence time of the organic solid waste corresponding to the anaerobic digestion substrate in the anaerobic digestion reactor.

8. The system according to claim 7, characterized in that, The formula for calculating the residence time of the anaerobic digestion substrate in the bypass device includes: Among them, T 旁 V is the residence time of the anaerobic digestion substrate in the bypass device. 旁 V is the volume of the bypass device; 主 T is the volume of the anaerobic digester reactor. 主 is the residence time of the organic solid waste corresponding to the anaerobic digestion substrate in the anaerobic digestion reactor; k is the minimum ratio of the anaerobic digestion substrate in the bypass device to the anaerobic digestion substrate in the anaerobic digestion reactor.

9. The system according to claim 4, characterized in that, The distance between the cathode and the anode is determined by a preset mass and a preset resistance; the preset mass is the minimum mass of the anaerobic digestion substrate that the bypass device can enhance; the preset resistance is the maximum resistance between the cathode and the anode.

10. The system according to claim 6, characterized in that, The transformer is also used to determine the regulated voltage based on the activity of microorganisms in the anaerobic digestion substrate.

Images