Closed solid fermentation system and method combining algal cultivation and aquaculture

Abstract

This invention provides a closed-loop solid-state fermentation system and method combining algae cultivation and aquaculture, relating to the fields of agricultural waste resource utilization and ecological circular agriculture. The system includes: a closed-loop solid-state fermentation reactor equipped with an intelligent temperature monitoring component for real-time acquisition of the average temperature T; an ecological fishpond with an aeration device at the bottom; a gas collection and distribution unit, including a blower and gas pipelines; the blower is installed on the gas pipelines; the gas pipelines are connected to the exhaust port of the closed-loop solid-state fermentation reactor and the aeration device of the ecological fishpond; and a control unit configured to control the operating frequency of the blower based on the average temperature T to maintain the average temperature T within the closed-loop solid-state fermentation reactor within the range of 50℃-55℃. This invention innovatively constructs a multi-phase coupled material and energy cycle closed-loop system of "gas-algae-fish-fertilizer".

Description

Technical Field

[0001] This invention relates to the field of agricultural waste resource utilization and ecological circular agriculture technology, and in particular to a closed solid fermentation system and method that combines algae cultivation and aquaculture. Background Technology

[0002] With the rapid development of intensive agriculture, the amount of organic solid waste such as livestock and poultry manure, straw, and kitchen waste has increased dramatically. Their harmless treatment and resource utilization have become key challenges for sustainable agricultural development. Currently, aerobic composting is the mainstream technology for treating such waste. However, traditional open or semi-closed composting processes have significant technical bottlenecks: On the one hand, to meet the hygienic standards for killing pathogens and weed seeds, the compost temperature often needs to rise to 60℃ or even above 70℃. While this sustained high-temperature environment achieves harmlessness, it leads to severe thermal decomposition of heat-sensitive beneficial nutrients such as amino acids and vitamins, significantly reducing the agricultural value of compost products and their potential as feed additives. On the other hand, the large amount of malodorous waste gas containing ammonia, hydrogen sulfide, and volatile organic compounds generated during composting not only causes the loss of key nutrients such as nitrogen but also triggers serious air pollution and NIMBY (Not In My Backyard) effects. Existing end-of-pipe treatment methods such as membrane covering or biofiltration can partially alleviate the odor, but they fail to achieve the recycling of carbon and nitrogen resources in the waste gas, resulting in secondary waste of resources.

[0003] Meanwhile, aquaculture is facing multiple pressures, including high feed costs, increasing eutrophication, and enormous energy consumption for aeration. While microalgae cultivation can be an effective way to solve feed sourcing and water purification, its large-scale application is limited by the high input costs of carbon and nitrogen sources. Existing technologies, although some studies have attempted to use compost waste gas for algae cultivation, mostly treat waste treatment, algae cultivation, and aquaculture as independent processes, lacking a systematic integrated design. They have not established a dynamic matching mechanism between waste gas heat and material flow and the needs of fishponds, resulting in unutilized heat energy in the waste gas, large fluctuations in gas composition, and even the potential for excessively high temperatures to harm aquatic organisms.

[0004] Therefore, there is an urgent need to develop a system that can deeply integrate the closed fermentation of organic solid waste, the resource utilization of waste gas and waste heat, and ecological aquaculture, and build an ecological cycle chain of "waste-fertilizer / feed-aquatic products" to simultaneously solve the problems of environmental pollution, nutrient loss and high breeding costs. Summary of the Invention

[0005] To address the technical problems existing in the prior art, embodiments of the present invention provide a closed solid-state fermentation system and method combining algae cultivation and aquaculture. The technical solution is as follows:

[0006] This invention provides a closed solid-state fermentation system combining algae cultivation and aquaculture, comprising:

[0007] A closed solid-state fermentation reactor is provided with an exhaust port; the closed solid-state fermentation reactor is equipped with an intelligent temperature monitoring component to obtain the average temperature T inside the closed solid-state fermentation reactor in real time.

[0008] The ecological fishpond is equipped with an aeration device at the bottom.

[0009] A gas collection and distribution unit includes a blower and a gas pipeline; the blower is installed on the gas pipeline; the inlet of the gas pipeline is connected to the exhaust port of the closed solid fermentation reactor, and the outlet of the gas pipeline is connected to the aeration device at the bottom of the ecological fishpond.

[0010] The control unit is electrically connected to the intelligent temperature monitoring component and the fan respectively; the control unit is configured to control the operating frequency of the fan according to the average temperature T so that the average temperature T in the closed solid fermentation reactor is maintained within the range of 50℃-55℃.

[0011] Optionally, the control unit is configured to control the fan to operate at 25%-40% of the rated frequency when the average temperature T < 50℃; to control the fan to operate at 45%-75% of the rated frequency when the average temperature 50℃ ≤ T ≤ 55℃; and to control the fan to operate at 80%-100% of the rated frequency when the average temperature T > 55℃.

[0012] Optionally, the intelligent temperature monitoring component includes:

[0013] A temperature sensor array, distributed at multiple points within the closed solid-state fermentation reactor, is used to monitor the temperature of the pile at different locations within the closed solid-state fermentation reactor.

[0014] The data processing unit is electrically connected to the temperature sensor array and the control unit, respectively, and is used to calculate the average temperature T of the stack temperature at different locations and output it to the control unit.

[0015] Optionally, the exhaust port of the closed solid fermentation reactor is covered with a sealing functional membrane, which is one of PO membrane, PTFE membrane or composite microporous membrane.

[0016] Optionally, the exhaust gas discharged from the exhaust outlet of the closed solid fermentation reactor contains carbon dioxide, water vapor, ammonia, and volatile organic compounds.

[0017] This invention also provides a closed solid-state fermentation method combining algae cultivation and aquaculture using the system described above, comprising the following steps:

[0018] Organic solid waste is fed into the closed solid fermentation reactor for fermentation;

[0019] The average temperature T inside the closed solid-state fermentation reactor is acquired in real time.

[0020] The operating frequency of the fan is controlled according to the average temperature T so that the average temperature T is maintained within the range of 50℃-55℃;

[0021] The waste gas generated in the closed solid fermentation reactor is transported to the bottom aeration device of the ecological fishpond through a gas pipeline for aeration.

[0022] Optionally, when the average temperature T < 50°C, the fan is controlled to operate at 25%-40% of its rated frequency;

[0023] When the average temperature is 50℃≤T≤55℃, the fan is controlled to operate at 45%-75% of its rated frequency;

[0024] When the average temperature T > 55℃, the fan is controlled to operate at 80%-100% of the rated frequency.

[0025] Optionally, the solid fermentation products produced in the closed solid fermentation reactor are used as organic fertilizer after decomposition; the bottom mud of the ecological fishpond is recycled as organic solid waste in the closed solid fermentation reactor.

[0026] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0027] (1) The present invention combines algae cultivation and aquaculture in a closed solid fermentation system. By strictly controlling the high temperature period of solid fermentation within 50℃-55℃, it ensures the effective killing of pathogens while avoiding the damage of heat-sensitive substances caused by traditional high temperatures, and improves the retention rate of free amino acids and B vitamins in organic fertilizer. The system innovatively constructs a closed-loop material and energy cycle system of "gas-algae-fish-fertilizer" multiphase coupling, and directionally transports fermentation waste gas rich in CO2, ammonia nitrogen and sensible heat to ecological fish ponds. This not only promotes the increase of algae biomass and reduces the fish feed coefficient, but also uses waste heat to raise the water temperature in winter. Furthermore, it significantly reduces energy consumption by integrating the functions of fermentation ventilation and fish pond aeration, and realizes diversified high-value output from organic waste to high-quality fertilizer, protein feed and aquatic products. At the same time, the system has the ability to adaptively and intelligently regulate based on real-time temperature, which can effectively overcome the interference of environmental and material fluctuations, and ensure efficient and stable operation and low maintenance costs.

[0028] (2) The system of the present invention uses the dual mechanism of “closed functional membrane covering and full exhaust gas delivery” to block the unorganized emission of odorous gases such as ammonia and hydrogen sulfide from the source and convert them into a source of nutrients for water bodies, thus completely solving the problem of odor nuisance caused by traditional composting. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0030] Figure 1 This is a schematic diagram of a closed solid-state fermentation system combining algae cultivation and aquaculture, provided by an embodiment of the present invention.

[0031] Figure label:

[0032] 1-Closed solid-state fermentation reactor; 11-Inlet; 12-Outlet; 13-Ventilation port; 14-Exhaust gas outlet; 15-Sealed functional membrane;

[0033] 2-Ecological fishpond; 21-Aeration device;

[0034] 31-Fan; 32-Gas pipeline;

[0035] 41-Temperature sensor array;

[0036] 5-Control unit. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms “first,” “second,” and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms “an,” “a,” or “the,” and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms “comprising,” “including,” or “including,” and similar terms mean that the element or object preceding the word encompasses the element or object listed following the word and its equivalents, without excluding other elements or objects. The terms “connected,” “linked,” or “connected,” and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0039] It should be noted that the terms "up", "down", "left", "right", "front" and "back" used in this invention are only used to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0040] This invention provides a closed solid-state fermentation system combining algae cultivation and aquaculture, achieving resource utilization of organic waste through the coupling of material and energy flows. For example... Figure 1 As shown, the system includes: a closed solid fermentation reactor 1, an ecological fishpond 2, a gas collection and distribution unit, and a control unit 5.

[0041] The closed solid-state fermentation reactor 1 is a static chamber structure, preferably constructed of reinforced concrete or corrosion-resistant insulation panels. The closed solid-state fermentation reactor 1 has a vent 13 at the bottom, a feed inlet 11 for feeding and a discharge outlet 12 for discharging on the side, and an exhaust outlet 14 at the top.

[0042] An intelligent temperature monitoring component is installed inside the closed solid-state fermentation reactor 1. This component includes a temperature sensor array 41 and a data processing unit. The temperature sensor array 41 is arranged in a multi-point distribution manner, including at least three temperature sensors, which are respectively arranged in the upper, middle, and lower parts of the pile within the closed solid-state fermentation reactor 1, or distributed in a matrix at different depths within the pile. Each temperature sensor collects the pile temperature signal at its location in real time and transmits it to the data processing unit. The data processing unit calculates the average temperature T within the closed solid-state fermentation reactor 1 from the pile temperatures at different locations and outputs it to the control unit 5.

[0043] The exhaust port 14 at the top of the closed solid-state fermentation reactor 1 is covered with a sealing functional membrane 15. In this embodiment, the sealing functional membrane 15 is selected from PO membrane, PTFE membrane, or composite microporous membrane. This sealing functional membrane 15 has selective permeability characteristics: it allows water vapor and small molecule gases (such as CO2 and NH3) to pass through, but effectively blocks aerosols, dust, and most large odorous molecules, thereby forming an in-situ deodorization and nitrogen retention layer at the top of the reactor. The exhaust port 14 of the closed solid-state fermentation reactor 1 is located in the gas collection space below the sealing functional membrane 15, ensuring that the discharged gas mainly comes from the biological waste gas generated during the fermentation process.

[0044] Ecological fishpond 2 is a conventional aquaculture water body, with an aeration device 21 installed at its bottom. In this embodiment, the aeration device 21 includes a microporous aeration pipe network laid on the bottom of the pond. The air inlet of the aeration pipe network extends to the shore via a pipe, serving as the outlet connection point of the gas pipeline 32. Conventional freshwater fish (such as grass carp and silver carp) are raised in ecological fishpond 2, and the CO2, NH3, and nutrients in the fermentation waste gas are used to promote the growth of phytoplankton (algae), forming a "gas-algae-fish" symbiotic environment.

[0045] The gas collection and distribution unit includes a blower 31 and a gas pipeline 32. The blower 31 is a variable frequency blower, with its speed infinitely adjustable within the range of 0-1500 rpm. The blower 31 is connected in series to the gas pipeline 32. The gas pipeline 32 uses corrosion-resistant pipes (such as UPVC or HDPE pipes). The inlet of the gas pipeline 32 is sealed to the exhaust port 14 of the closed solid-state fermentation reactor 1, and the outlet of the gas pipeline 32 is connected to the aeration device 21 at the bottom of the ecological fishpond 2. Through this connection, the waste gas generated in the closed solid-state fermentation reactor 1 is forcibly transported to the bottom of the ecological fishpond 2, directly participating in the water aeration and fertilization process.

[0046] The control unit 5 is an industrial PLC controller or an embedded microprocessor, which is electrically connected to the intelligent temperature monitoring component and the fan 31, respectively. The control unit 5 has a temperature control program pre-stored inside. The core logic of this program is to dynamically adjust the operating frequency of the fan 31 based on the real-time average temperature T to achieve precise temperature control.

[0047] In this embodiment, the control unit 5 is configured to execute the following three-stage control strategy:

[0048] Heating Phase (Low Temperature Zone): When the average temperature T received by control unit 5 is < 50℃, the pile is determined to be in the initial stage of heating or in a state of insufficient heat. At this time, control unit 5 instructs fan 31 to operate at a low frequency (e.g., the frequency is set to 25%-40% of the rated frequency, corresponding to a smaller air volume). Reducing the ventilation volume aims to reduce convective heat loss and utilize the metabolic heat of microorganisms to promote a rapid rise in the pile temperature, so as to enter the high-temperature fermentation period as soon as possible.

[0049] Constant-temperature fermentation stage (optimal temperature zone): When the average temperature T is within the range of 50℃≤T≤55℃, the compost pile is considered to be in the optimal fermentation state. Within this temperature range, most pathogens and weed seeds can be effectively killed, while heat-sensitive nutrients such as amino acids and vitamins will not undergo significant decomposition. At this time, the control unit 5 instructs the fan 31 to operate at a medium frequency (for example, the frequency is set to 45%-75% of the rated frequency). The amount of oxygen provided by this wind speed is just enough to maintain the aerobic metabolism of microorganisms, while removing excess heat, so that the average temperature T is stably maintained within 50℃-55℃.

[0050] Cooling Protection Phase (High Temperature Zone): When the average temperature T > 55℃, the reactor is deemed to be at risk of overheating, which may lead to the destruction of beneficial substances or the generation of excessively hot exhaust gases that could damage subsequent algae / fish. At this time, the control unit 5 instructs the fan 31 to operate at a high frequency (e.g., the frequency is set to 80%-100% of the rated frequency, operating at full load). The ventilation volume is increased to enhance evaporative and convective heat dissipation, rapidly reducing the reactor temperature back to the safe range of 50℃-55℃.

[0051] Through the above closed-loop feedback control, the system can automatically adapt to different ambient temperatures, different material moisture contents and different fermentation stages of thermal changes, and always lock the core fermentation temperature within the range of 50℃-55℃.

[0052] This invention also provides a method for treating organic waste and aquaculture using the above system, the specific operation steps of which are as follows:

[0053] Step S1: Feeding and Start-up

[0054] Pretreated organic solid waste (such as crushed straw, dehydrated livestock and poultry manure, or kitchen waste with a moisture content adjusted to 55%-65%) is fed into the closed solid fermentation reactor 1 through the feed inlet 11. The system is started, and the control unit 5 begins to work.

[0055] Step S2: Real-time monitoring and temperature-controlled fermentation

[0056] The temperature sensor array 41 monitors the reactor temperature in real time and the data is aggregated into an average temperature T by the data processing unit and transmitted to the control unit 5.

[0057] If the initial temperature is low (T < 50℃), the blower 31 will operate at a low frequency, and the reactor temperature will gradually increase.

[0058] When the temperature rises above 50℃, fan 31 automatically switches to medium frequency, maintaining the temperature between 50℃ and 55℃ for continuous fermentation for 15-20 days. During this period, microorganisms efficiently degrade organic matter, producing exhaust gas rich in water vapor, CO2, NH3, and a small amount of volatile organic compounds.

[0059] If T > 55℃ is caused by local overheating, fan 31 will immediately operate at high frequency to intervene until the temperature drops.

[0060] This process ensures a high retention rate of heat-sensitive nutrients in the fermentation products (organic fertilizer), while also maintaining a suitable temperature for the exhaust gas, thus avoiding any impact on the fishpond ecosystem.

[0061] Step S3: Waste gas resource utilization

[0062] The waste gas generated during fermentation is filtered by the closed functional membrane 15 to remove aerosols, and then drawn into the gas pipeline 32 by the blower 31, and finally transported to the aeration device 21 at the bottom of the ecological fishpond 2.

[0063] As the exhaust gas bubbles rise, they increase dissolved oxygen in the water, achieving aeration and oxygenation. The sensible heat carried by the exhaust gas helps raise the water temperature during cold seasons, extending the growth period of fish. The CO2 in the exhaust gas dissolves in the water, serving as an inorganic carbon source to promote photosynthesis in phytoplankton (algae). The NH3 in the exhaust gas dissolves in the water to form ammonium nitrogen, which is directly absorbed and utilized by algae as nitrogen fertilizer. With the increase in algal biomass, algae serve as natural food for filter-feeding fish (such as silver carp and bighead carp) and can also be periodically harvested and processed into high-protein feed additives.

[0064] Step S4: Product Output and Recycling

[0065] After the material in the closed solid fermentation reactor 1 has decomposed, it is discharged through the discharge port 12 to obtain high-quality organic fertilizer, which can be directly returned to the field or used as a seedling substrate.

[0066] After a breeding cycle, the bottom sediment of ecological fishpond 2 is rich in unutilized organic matter and algal residue. This sediment is dredged out and used as new organic solid waste raw material, which is then fed back into the closed solid fermentation reactor 1 for fermentation treatment, thereby achieving a complete ecological closed loop of "waste-fertilizer / feed-aquatic products-waste".

[0067] Comparative experiments revealed that the system and method of this invention, through precise temperature control strategies, strictly locks the temperature fluctuation range during the high-temperature period of solid-state fermentation within the range of 50℃ to 55℃ (±2.5℃), effectively overcoming the defects of drastic temperature fluctuations (40℃-75℃) in traditional natural ventilation composting. This precise temperature control not only significantly increases the content of heat-sensitive free amino acids and the retention rate of B vitamins in organic fertilizer products by approximately 30% and 25% respectively compared to traditional high-temperature composting (>65℃), achieving efficient nutrient preservation, but also directs the waste gas rich in carbon dioxide and nitrogen to the ecological fishpond 2, promoting a 40% increase in algal biomass and a 15% reduction in the fish feed conversion ratio. Furthermore, it utilizes waste heat to raise the average water temperature by 1-2℃ in winter, thereby significantly reducing aquaculture costs while significantly reducing the concentration of ammonia and hydrogen sulfide around the plant area, constructing an ecological closed-loop system integrating high-quality fertilizer production, efficient aquaculture, and resource-based transformation of pollutants at the source.

[0068] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A closed solid-state fermentation system combining algae cultivation and aquaculture, characterized in that, include: A closed solid-state fermentation reactor is provided with an exhaust port; the closed solid-state fermentation reactor is equipped with an intelligent temperature monitoring component to obtain the average temperature T inside the closed solid-state fermentation reactor in real time. The ecological fishpond is equipped with an aeration device at the bottom. A gas collection and distribution unit includes a blower and a gas pipeline; the blower is installed on the gas pipeline; the inlet of the gas pipeline is connected to the exhaust port of the closed solid fermentation reactor, and the outlet of the gas pipeline is connected to the aeration device at the bottom of the ecological fishpond. The control unit is electrically connected to the intelligent temperature monitoring component and the fan respectively; the control unit is configured to control the operating frequency of the fan according to the average temperature T so that the average temperature T in the closed solid fermentation reactor is maintained within the range of 50℃-55℃.

2. The closed solid-state fermentation system combining algae cultivation and aquaculture according to claim 1, characterized in that, The control unit is configured to control the fan to operate at 25%-40% of the rated frequency when the average temperature T < 50℃; to control the fan to operate at 45%-75% of the rated frequency when the average temperature 50℃ ≤ T ≤ 55℃; and to control the fan to operate at 80%-100% of the rated frequency when the average temperature T > 55℃.

3. The closed solid-state fermentation system combining algae cultivation and aquaculture according to claim 1, characterized in that, The intelligent temperature monitoring component includes: A temperature sensor array, distributed at multiple points within the closed solid-state fermentation reactor, is used to monitor the temperature of the pile at different locations within the closed solid-state fermentation reactor. The data processing unit is electrically connected to the temperature sensor array and the control unit, respectively, and is used to calculate the average temperature T of the stack temperature at different locations and output it to the control unit.

4. The closed solid-state fermentation system combining algae cultivation and aquaculture according to claim 1, characterized in that, The exhaust port of the closed solid fermentation reactor is covered with a sealing functional membrane, which is one of PO membrane, PTFE membrane or composite microporous membrane.

5. The closed solid-state fermentation system combining algae cultivation and aquaculture according to claim 1, characterized in that, The exhaust gas discharged from the exhaust port of the closed solid fermentation reactor contains carbon dioxide, water vapor, ammonia, and volatile organic compounds.

6. A closed solid-state fermentation method combining algae cultivation and aquaculture using the system described in any one of claims 1 to 5, characterized in that, Includes the following steps: Organic solid waste is fed into the closed solid fermentation reactor for fermentation; The average temperature T inside the closed solid-state fermentation reactor is acquired in real time. The operating frequency of the fan is controlled according to the average temperature T so that the average temperature T is maintained within the range of 50℃-55℃; The waste gas generated in the closed solid fermentation reactor is transported to the bottom aeration device of the ecological fishpond through a gas pipeline for aeration.

7. The method according to claim 6, characterized in that, When the average temperature T < 50℃, the fan is controlled to operate at 25%-40% of its rated frequency; When the average temperature is 50℃≤T≤55℃, the fan is controlled to operate at 45%-75% of its rated frequency; When the average temperature T > 55℃, the fan is controlled to operate at 80%-100% of the rated frequency.

8. The method according to claim 6, characterized in that, The solid fermentation products produced in the closed solid fermentation reactor are used as organic fertilizer after decomposition; the bottom mud of the ecological fishpond is recycled as organic solid waste in the closed solid fermentation reactor.

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