Nuclear waste fractionation bioprocessing and containment system and method

Abstract

The application relates to a nuclear waste grading biological treatment and shielding system and method, and belongs to the technical field of nuclear waste treatment and radiation protection. The system comprises: a primary wastewater biological treatment unit used for adsorbing and enriching radionuclides in radioactive wastewater by using mycelium of melanin-producing fungi, and collecting waste fungal biomass after adsorption saturation; and a secondary waste resourceization and shielding unit used for taking the waste fungal biomass as shielding material for deep geological disposal, and early warning radionuclide leakage risk by monitoring metabolic activity of fungi in the waste fungal biomass. The method adopts the system to perform nuclear waste grading biological treatment and shielding. The application realizes synergistic effect, cost reduction, waste resourceization and utilization in the whole process from wastewater treatment to final disposal.

Description

Technical Field

[0001] This invention belongs to the field of nuclear waste treatment and radiation protection technology, specifically involving a graded biological treatment and shielding system and method for nuclear waste based on melanin-producing fungi. It utilizes the mycelium of melanin-producing fungi to purify radioactive wastewater and recycles the waste biomass generated during the purification process, forming a comprehensive solution with radiation shielding, biological monitoring and potential remediation. Background Technology

[0002] Currently, the treatment and disposal of radioactive liquid and solid waste generated by nuclear power plants mainly rely on mature physicochemical methods and deep geological disposal technologies in industry, but these methods have a series of inherent technical defects.

[0003] In treating low-to-medium level radioactive wastewater, existing technologies employ a combined process of "chemical precipitation-ion exchange-evaporation concentration." This process first adds chemical agents, such as ferric hydroxide and barium salts, to the wastewater, causing the main radionuclides, such as cesium-137 and strontium-90, to co-precipitate. Then, the supernatant is passed through an ion exchange resin bed to adsorb and remove dissolved ions. Finally, a large amount of water is evaporated through an evaporator, concentrating the radionuclides in a small amount of residual liquid for solidification. While effective, this traditional approach has several significant drawbacks: First, high operating costs, primarily due to the frequent regeneration and replacement of the ion exchange resin and the large amount of heat required for the evaporation process. Second, the process generates new secondary waste, such as precipitated sludge, saturated resin, and concentrated evaporation liquid, increasing the volume and cost of subsequent solidification and final disposal. Third, evaporation is an energy-intensive process, contradicting the concept of green and low-carbon development. Fourth, its function is limited, focusing solely on wastewater purification and lacking extended functions such as radiation shielding or system status monitoring.

[0004] In the final disposal of high-level radioactive solid waste, existing technologies employ a multi-layered engineering barrier system within deep geological repositories. The core structure includes a vitrified body, metal waste containers, bentonite buffer material, and concrete lining. Specifically, the high-level waste is vitrified, encapsulated in stainless steel or carbon steel containers, and placed hundreds of meters underground in deep geological structures. The containers are surrounded by bentonite, and the repositories' tunnels are constructed of concrete. The main drawbacks of this system are: first, the engineering barriers are static and passive; once installed, the performance of the concrete and bentonite naturally degrades over time, making it unable to proactively respond to potential corrosion or other changes in the internal state of the waste containers; second, the system severely lacks self-healing and real-time monitoring capabilities; if a leak occurs in the waste container, radioactive nuclides will enter the buffer material and surrounding rock, and existing technologies struggle to provide early warning, let alone proactively prevent or repair leaks; finally, the production process of barrier materials such as cement and steel is itself highly carbon-intensive and consumes enormous resources.

[0005] In related research, scientific literature and patents have explored the application of biomass in relevant fields. For example, the research "Ionizing Radiation Changes the Electronic Properties of Melanin and Enhances the Growth of Melanized Fungi," published by Dadachova et al. in the journal *PLOS ONE* in 2007, revealed the alteration of the electronic properties of melanin-producing fungi under radiation and their enhanced growth. Furthermore, various communities of "radiotropic fungi" exhibiting radiotropic growth were also discovered in the Chernobyl nuclear power plant ruins. In the patent field, although there are some schemes for treating uranium-containing wastewater using microbial agents, such as CN108217975A, their mechanism of action mainly relies on biosorption and does not involve the use of radiation energy for metabolism or the subsequent use of biomass for shielding and monitoring. Similarly, there are patents for preparing thermal and sound insulation materials using fungal mycelium, such as CN114961082A, but these are not specifically designed for the specific fields of radiation shielding and nuclear waste treatment.

[0006] In addition, there have long been two technical biases in the field of nuclear waste treatment and disposal.

[0007] First, the use of active biological barrier materials is currently prohibited in high-radiation environments. Deep geological disposal of high-level radioactive waste relies on multi-layered engineered barrier systems, the core design requirement of which is that the barrier materials must maintain long-term chemical and mechanical stability over a service life of hundreds to thousands of years. The prevailing understanding in the field is that bio-organic materials inevitably undergo radiation degradation and biological deterioration in high-radiation dose fields and long-term geological disposal environments, making them unsuitable as engineering barrier materials for high-level radioactive waste repositories. This understanding is reflected in industrial practice: existing and under-construction deep geological repositories are entirely constructed of inorganic materials, such as bentonite, cement-based materials, and steel, excluding any active biological components. For example, the current international practice for high-level radioactive waste disposal commonly employs a multi-layered engineered barrier system consisting of vitrified solids, metal waste containers, bentonite buffer materials, and concrete lining. This system is entirely based on inert inorganic components and contains no active biological components. However, research shows that some melanin-producing fungi exhibit significant tolerance to ionizing radiation; their melanin can capture radiation energy and convert it into chemical energy, thereby maintaining or enhancing the fungal metabolic activity. These findings suggest that certain fungi do not necessarily lose their biological functions in high-radiation environments. However, due to the aforementioned biases, those skilled in the art have generally not considered incorporating them into the engineering barrier system of the disposal repository.

[0008] Second, radioactive wastewater treatment and solid waste disposal are currently two separate treatment stages, and their materials should not be used interchangeably. In current nuclear industry practice, radioactive liquid waste treatment and solid waste disposal are usually implemented separately by different process units, following different technical standards and specifications. The industry generally regards sludge and residues generated from wastewater treatment as "secondary waste," which is disposed of as solid waste after further solidification, and has never considered them as functional raw materials that can be used for constructing disposal reservoir barriers. However, existing patents, such as CN117280426A, clearly record the use of fungi such as Cladosporium as the main component of radiation shielding materials, confirming that fungal mycelium and melanin have practically usable radiation shielding functions, rather than remaining only at the laboratory research stage. However, influenced by the technical bias of "separation between treatment and disposal fields," existing technologies have never proposed the idea of ​​using waste fungal biomass generated in the wastewater treatment stage as a material for disposal reservoir shielding barriers for resource utilization, failing to couple the potential waste and materials in the two technical fields of wastewater purification and solid waste disposal across fields.

[0009] Due to the aforementioned two technological biases, existing technologies have failed to provide a comprehensive technical solution that integrates wastewater biological purification, waste biomass resource recycling, and the construction of a shielding barrier for the disposal reservoir. Summary of the Invention

[0010] The purpose of this invention is to overcome the aforementioned technical biases in existing nuclear waste treatment technologies and provide a graded biological treatment and shielding system and method for nuclear waste. This system integrates biological treatment, resource utilization, shielding protection, and status monitoring, providing an economical, environmentally friendly, and multifunctional integrated solution that achieves efficiency improvement and cost reduction throughout the entire process from wastewater treatment to final disposal, as well as the resource utilization of waste.

[0011] To achieve the above objectives, in one respect, the present invention provides a graded biological treatment and shielding system for nuclear waste based on melanin-producing fungi, comprising: The primary wastewater biological treatment unit is used to utilize the mycelium of melanin-producing fungi to adsorb and enrich radionuclides in radioactive wastewater, and to collect the waste fungal biomass after adsorption saturation. The secondary waste resource utilization and shielding unit is used to use waste fungal biomass as a shielding material for deep geological disposal, and to monitor the metabolic activity of fungi in the waste fungal biomass to provide early warning of the risk of radionuclide leakage. The primary wastewater biological treatment unit includes: Radioactive wastewater storage tanks are used to temporarily store low- to intermediate-level radioactive wastewater generated during the operation of nuclear power plants. The fungal bioreactor has a first inlet at the top connected to the outlet of a radioactive wastewater storage tank via an inlet valve and pump; a second inlet at the top connected to an external purified water source via a backwash valve and pump; an aeration device at the bottom inlet to introduce sterile air or sterile oxygen into the fungal bioreactor to maintain the aerobic metabolism of melanin-producing fungi; a purified water outlet and a biomass discharge outlet at the bottom; an internal mycelial packing layer composed of mycelia of non-pathogenic, highly radiation-resistant melanin-producing fungi to adsorb and concentrate radionuclides in low-radioactive wastewater; and a stirring device above the internal mycelial packing layer to promote fluid mixing. The waste fungal biomass collector has its inlet connected to the biomass outlet of the fungal bioreactor via a valve, and is used to collect waste fungal biomass after adsorption saturation. The secondary waste resource recovery and shielding unit includes: Matrix material storage compartment, used for storing matrix materials; The mixing agitator has its first inlet connected to the outlet of the waste fungal biomass collector via a screw conveyor, and its second inlet connected to the outlet of the substrate material silo via a metering conveyor belt. It is used to mix the waste fungal biomass and substrate material in a proportional and uniform manner to form a mixture. A pressing molding machine, the inlet of which is connected to the outlet of a mixing agitator, is used to press the mixture into matrix-fungus composite shielding bricks; The deep geological disposal facility contains metal waste tanks that hold high-level radioactive waste glass solidifiers. The metal waste tanks are surrounded by a bentonite buffer layer and an inner lining layer made of matrix-fungus composite shielding bricks. At least one metabolic activity monitoring sensor; the metabolic activity monitoring sensor is an integrated multi-parameter sensor, which is embedded in the inner liner layer to synchronously and in real time detect CO2 concentration, relative humidity and temperature in the inner liner layer, thereby monitoring the metabolic activity of melanin-producing fungi in real time.

[0012] As one feasible approach, the packing density of the mycelium packing layer is 50~150 g dry weight / L packing volume, and the specific oxygen consumption rate of the melanin-producing fungal mycelium at 25~30℃ is 0.5~2.0 mg O2 / (g dry weight·h). As one possible approach, the mycelium in the mycelium packing layer exists in the form of mycelial balls or is attached to a porous carrier in an immobilized manner; when the mycelium exists in the form of mycelial balls, the diameter of the mycelial balls is 1~10 mm, preferably 2~5 mm; when the mycelium is attached to a porous carrier in an immobilized manner, the porous carrier is preferably polyvinyl alcohol compounded with sodium alginate, or polyurethane foam; The filling height of the mycelium packing layer is 1 / 2 to 2 / 3 of the effective height of the fungal bioreactor.

[0013] As one feasible approach, non-pathogenic, highly radiation-tolerant melanin-producing fungi are obtained through screening and / or domestication using the following methods: (1) Selection of starting strain: Select melanin-producing fungi with radiation tolerance as starting strains, including but not limited to one or more of Cryptococcus neoformans, Cladosporium, Exospirolium and Brachymycota; the starting strains are identified or confirmed to be non-pathogenic or low-pathogenic strains through genetic engineering. (2) Adaptive laboratory evolution: The starting strain was inoculated into a liquid culture medium containing a gradient concentration of radionuclides, with the radioactivity concentration ranging from 10... 2 Bq / mL gradually increased to 10 5 Continuous subculturing was carried out under the condition of Bq / mL, with each generation lasting 7-14 days and a total of no less than 10 generations. This allowed the fungi to accumulate adaptive mutations to the high-radiation environment under continuous selection pressure, resulting in the domesticated fungal population. (3) Screening of highly tolerant strains: The domesticated bacterial population was spread on solid culture medium plates and cultured for 7 to 14 days under γ-ray or X-ray irradiation with a dose rate of 10 to 100 Gy / h. Single colonies with normal growth and significant melanin phenotype were selected. The selected colonies were exposed to γ-ray irradiation with increasing doses and the survival rate of each strain was determined. Mutants with a half-lethal dose ≥ 1.0 kGy or a survival rate significantly higher than that of the starting strain at the target dose were selected as non-pathogenic, highly radiation-tolerant melanin-producing fungal strains.

[0014] As one possible approach, a water distributor is installed at the top inlet of the fungal bioreactor, and an effluent screen is installed at the purified water outlet.

[0015] As one possible approach, the matrix material is one or more of bentonite, gypsum, cement, or biodegradable polymer; the radial thickness of the bentonite buffer layer is 30-50 cm, and the bentonite is preferably high-pressure compacted sodium-based bentonite; the thickness of the inner lining layer is 20-50 cm.

[0016] To achieve the above objectives, the present invention also provides a method for graded biological treatment and shielding of nuclear waste based on melanin-producing fungi. The system for graded biological treatment and shielding of nuclear waste based on melanin-producing fungi includes the following steps: S1. Pump the radioactive wastewater in the radioactive wastewater storage tank into the fungal bioreactor, so that it flows through the mycelial packing layer. At the same time, start the stirring device and the aeration device. The aeration device introduces sterile air or sterile oxygen into the fungal bioreactor, and the stirring device promotes the mixing of fluids in the fungal bioreactor. Melanin-producing fungi absorb the ionizing radiation released by radionuclides in radioactive wastewater and convert it into chemical energy required for mycelial growth and metabolism through radiosynthesis, thereby achieving the bioadsorption, enrichment and purification of radionuclides. S2. When the mycelium packing layer is saturated with adsorption, the waste fungal biomass is transported to the waste fungal biomass collector by backwashing or direct discharge. S3: The waste fungal biomass in the waste fungal biomass collector and the matrix material in the matrix material bin are put into the mixing mixer according to the predetermined mass ratio. After adding purified water and mixing evenly to form a mixture, it is sent to the pressing and molding machine to be pressed into a matrix-fungus composite shielding brick and cured. S4: In the deep geological treatment facility, after the metal waste tank containing the high-level radioactive waste vitrifier is placed in place, a bentonite buffer layer is filled around it, and a matrix-fungus composite shielding brick is used to build an inner lining layer around the buffer layer. At the same time, a metabolic activity monitoring sensor is embedded in the inner lining layer. S5: The metabolic activity monitoring sensor synchronously and in real time detects three parameters in the inner lining: CO2 concentration, relative humidity, and temperature. When a single parameter or a combination of parameters is abnormal, it is determined that the metabolic activity of melanin-producing fungi is abnormal, triggering a radionuclide leakage warning.

[0017] As one possible implementation method, in S1, radioactive wastewater in the radioactive wastewater storage tank is evenly sprayed into the fungal bioreactor from the top inlet water distributor through a pump at a flow rate of 0.5-2 times the volume of the fungal bioreactor per hour, and flows downward through the mycelial packing layer; the dissolved oxygen concentration in the fungal bioreactor is controlled at 2-4 mg / L, the temperature is controlled at 25-30℃, and the pH is controlled at 5.0-7.0; the stirring speed of the stirring device is controlled at 50-100 r / min.

[0018] As one possible implementation method, in S2, when the radionuclide removal rate of the mycelium packing layer is detected to decrease by 15% to 20% compared to the initial value, or the bed pressure drop increases to 1.5 to 2 times the initial pressure drop, the inlet valve is closed and the backwash valve is opened. Purified water from an external purified water source is used to backwash and regenerate the mycelium packing layer. The flow rate of the purified water during backwashing is 2 to 5 times the normal inlet flow rate, and the backwashing time is 3 to 8 minutes. The temperature inside the waste fungal biomass collector is maintained at 4℃, and the collected waste fungal biomass has a moisture content of 80-90%.

[0019] As one possible approach, in S3, the waste fungal biomass in the waste fungal biomass collector and the matrix material in the matrix material bin are added to a mixing mixer at a mass ratio of 1:1 to 1:3. 10% to 15% of the total mass of the waste fungal biomass and matrix material is added to purified water, and the mixture is stirred at a speed of 30 to 60 r / min for 15 to 25 minutes to form a mixture.

[0020] As one possible method, in S4, the pressing machine cold-presses the mixture into a matrix-fungus composite shielding brick under a pressure of 20~30 MPa; the matrix-fungus composite shielding brick is then cured for 7 days at a temperature of 25±3℃ and a relative humidity of 85±5%.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects: By using melanin-producing fungal mycelium to construct a bioreactor for treating radioactive wastewater, low-energy consumption, low-cost, and high-efficiency purification was achieved at ambient temperature and pressure. The purification process mainly relies on biological adsorption and fixation, avoiding the addition of chemical agents, thereby significantly reducing the generation of secondary waste such as chemical sludge.

[0022] By using waste fungal biomass generated during the purification process as the core raw material to prepare composite shielding bricks, the resource utilization of radioactive waste has been realized, turning waste into treasure. Simultaneously, this composite shielding brick, serving as the inner lining of a high-level radioactive waste disposal facility, contains melanin and organic matter components that can effectively scatter and absorb gamma rays and moderate neutrons, synergistically enhancing the radiation shielding effect of the engineering barrier in conjunction with bentonite.

[0023] By utilizing the metabolic activity of fungi as biosensors throughout the system, early, online, and non-destructive warnings of the integrity of the treatment reservoir barrier system hundreds of meters underground were achieved. Once fungal metabolic abnormalities are caused by leakage or groundwater intrusion, the sensors can immediately send signals, overcoming the shortcomings of traditional passive barriers that are "invisible and inaccurate to measure".

[0024] The comprehensive biological treatment solution provided by this invention, compared with traditional physicochemical methods, achieves greening, volume reduction and functional diversification of nuclear waste treatment as a whole, and has significant environmental and economic benefits. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a nuclear waste grading and biological treatment and shielding system according to an embodiment of the present invention.

[0026] In the diagram, 1. Radioactive wastewater storage tank; 2. Fungal bioreactor; 3. Mycelial packing layer; 4. Biomass discharge outlet; 5. Waste fungal biomass collector; 6. Matrix material silo; 7. Mixing agitator; 8. Press molding machine; 9. Matrix-fungus composite shielding brick; 10. High-level radioactive waste glass curing device; 11. Metal waste tank; 12. Deep geological disposal tank; 13. Bentonite buffer layer; 14. Inner lining layer; 15. Metabolic activity monitoring sensor. Detailed Implementation

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0028] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] In the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0030] The terms “upper,” “lower,” “left,” “right,” “front,” “back,” “top,” “bottom,” “inner,” and “outer,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use. They are only for the convenience of description and simplification, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0031] The terms “include,” “comprising,” or any other variation thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1 As shown, this invention provides an embodiment of a graded biological treatment and shielding system for nuclear waste based on melanin-producing fungi. This system provides a comprehensive solution that combines biological treatment technology with the engineering disposal of nuclear waste, enabling the full-process treatment from liquid radioactive waste to solid radioactive waste.

[0034] The nuclear waste tiered biological treatment and shielding system described in this embodiment includes: The primary wastewater biological treatment unit is used to utilize the mycelium of melanin-producing fungi to adsorb and enrich radionuclides in radioactive wastewater, and to collect the waste fungal biomass after adsorption saturation. The secondary waste resource utilization and shielding unit is used to use waste fungal biomass as a shielding material for deep geological disposal, and to provide early warning of radionuclide leakage risks by monitoring the metabolic activity of fungi in the waste fungal biomass.

[0035] In this embodiment, the primary wastewater biological treatment unit includes: Radioactive wastewater storage tank 1 is a sealed, corrosion-resistant stainless steel tank used for the temporary storage of radioactive wastewater generated during the operation of a nuclear power plant. The fungal bioreactor 2 is a closed, corrosion-resistant stainless steel reactor. Its top first inlet is connected to the outlet of the radioactive wastewater storage tank 1 via an inlet valve and pump. Its top second inlet is connected to an external purified water source via a backwash valve and pump. An aeration device is installed at its bottom inlet to introduce sterile air or sterile oxygen into the fungal bioreactor 2 to maintain the aerobic metabolism of the melanin-producing fungi. A purified water outlet and a biomass discharge outlet 4 are provided at the bottom. Inside, there is a mycelial packing layer 3, which is composed of non-pathogenic, highly radiation-resistant melanin-producing fungal mycelia to adsorb and enrich radionuclides in the radioactive wastewater. A stirring device is installed above the mycelial packing layer 3 to promote fluid mixing. The waste fungal biomass collector 5 is a sealed silo with stirring and cooling functions; its inlet is connected to the biomass outlet 4 at the bottom of the fungal bioreactor 2 via a valve, and is used to collect waste fungal biomass after adsorption saturation.

[0036] In this embodiment, the bulk density of the mycelium packing layer 3 is 50~150 g dry weight / L packing volume, and the specific oxygen consumption rate of the melanin-producing fungal mycelium at 25~30℃ is 0.5~2.0 mg O2 / (g dry weight·h).

[0037] In this embodiment, non-pathogenic, highly radiation-resistant melanin-producing fungi were obtained through screening and / or domestication using the following methods: (1) Selection of starting strain: Select melanin-producing fungi with known radiation tolerance as starting strains, including but not limited to one or more of Cryptococcus neoformans, Cladosporium spp., Exophiala spp. and Aureobasidium spp., Cladosporium spp. including but not limited to C. sphaerospermum, and Exophiala spp. including but not limited to E. dermatitidis; the above starting strains are identified or confirmed to be non-pathogenic or low-pathogenic strains through genetic engineering modification; (2) Adaptive laboratory evolution: The starting strain was inoculated into a liquid culture medium containing a gradient concentration of radionuclides, with the radioactivity concentration ranging from 10... 2 Bq / mL gradually increased to 10 5 Continuous subculturing was carried out under the condition of Bq / mL, with each generation lasting 7-14 days and a total of no less than 10 generations. This allowed the fungi to accumulate adaptive mutations to the high-radiation environment under continuous selection pressure, resulting in the domesticated fungal population. (3) Screening of highly tolerant strains: The acclimatized bacterial population was spread on solid culture medium plates and cultured for 7-14 days under γ-ray or X-ray irradiation at a dose rate of 10-100 Gy / h. Single colonies with normal growth and significant melanin phenotype were selected. The selected colonies were exposed to acute γ-ray irradiation at increasing doses, such as 0.5, 1.0, 2.0, 4.0, and 8.0 kGy, and the survival rate of each strain was determined. The median lethal dose (LD50) was selected. 50 Mutants with a survival rate ≥1.0 kGy or significantly higher than the starting strain at the target dose are considered as non-pathogenic, highly radiation-tolerant melanin-producing fungal strains.

[0038] In this embodiment, the mycelium in the mycelium packing layer 3 exists in the form of mycelial balls, or is attached to the porous carrier in an immobilized manner; When the mycelium exists in the form of mycelial balls, the diameter of the mycelial balls is 1~10 mm, preferably 2~5 mm. This particle size range gives the mycelial balls good settling properties, with a settling velocity ≥10 mm / s, which is beneficial for solid-liquid separation after treatment and the retention of mycelium in the reactor. When mycelia are immobilized and attached to a porous carrier, the porous carrier is preferably polyvinyl alcohol compounded with sodium alginate or polyurethane foam. Polyvinyl alcohol has been proven to be effective in encapsulating and immobilizing microorganisms when compounded with sodium alginate for column adsorption of radionuclides such as strontium. Polyurethane foam has been proven to be effective in immobilizing fungal mycelia for the treatment of uranium-containing wastewater. The immobilized mycelia exhibit enhanced mechanical strength and reusability during continuous operation. The filling height of the mycelium packing layer 3 is 1 / 2 to 2 / 3 of the effective height of the fungal bioreactor 2. This filling height range is the optimal compromise based on the following two engineering constraints: First, the filling height is directly proportional to the total number of adsorption sites and the residence time of wastewater in the mycelium packing layer 3. Insufficient filling height will lead to premature breakthrough time and decreased removal rate. Second, the filling height is limited by the mass transfer efficiency of oxygen to the interior of the mycelium packing layer 3 and the ability to dissipate metabolic heat. Excessive filling height will form an anoxic zone or a local overheated zone at the bottom of the mycelium packing layer 3, resulting in a decrease in fungal metabolic activity. After optimization, when the filling height of the mycelium packing layer 3 is 1 / 2 to 2 / 3 of the effective height of the fungal bioreactor 2, the aerobic metabolic activity and structural stability of the fungi in the entire mycelium packing layer 3 can be maintained while ensuring the removal rate of radionuclides.

[0039] In this embodiment, a water distributor is provided at the top inlet of the fungal bioreactor 2; and an outlet screen is provided at the bottom purified water outlet of the fungal bioreactor 2.

[0040] In this embodiment, the secondary waste resource recovery and shielding unit includes: The matrix material hopper 6 is a standard hopper used to store matrix materials; the matrix material is one or more of bentonite, gypsum, cement, or biodegradable polymers. The mixing mixer 7 is a double spiral belt mixer. Its first inlet is connected to the outlet of the waste fungal biomass collector 5 via a spiral conveyor, and its second inlet is connected to the outlet of the substrate material bin 6 via a metering conveyor belt. It is used to mix the waste fungal biomass and substrate material in proportion to form a mixture. The pressing and molding machine 8 is a hydraulic brick press. Its inlet is connected to the outlet of the mixing mixer 7. It is used to press the mixed materials into matrix-fungus composite shielding bricks 9 of preset shape and size according to the preset mold. The deep geological disposal facility 12 contains a metal waste tank 11 that holds a high-level radioactive waste vitrifier 10. The metal waste tank 11 is surrounded by a bentonite buffer layer 13 and an inner lining layer 14 constructed of matrix-fungus composite shielding bricks 9. The radial thickness of the bentonite buffer layer 13 is 30-50 cm, and the bentonite is preferably high-pressure compacted sodium-based bentonite, such as Gaomiaozi sodium-based bentonite. The bentonite buffer layer 13 provides mechanical buffering, hydraulic barrier, thermal conduction, and radionuclide chemical blocking functions. The inner lining layer 14 has a thickness of 20-50 cm and provides auxiliary radiation shielding, biological monitoring and early warning, and active bioremediation functions. The sum of the thicknesses of the bentonite buffer layer 13 and the inner lining layer 14 is 50-100 cm. The two layers, 1 cm and 14, constitute a three-tiered synergistic shielding system of "physical-chemical-biological": Under normal disposal conditions, the bentonite buffer layer 13 acts as a passive physical barrier, undertaking the main functions of nuclide blocking, mechanical protection, and heat conduction, while the fungi in the inner liner layer 14 maintain a dormant / low metabolic state and provide stable auxiliary radiation shielding; Under abnormal conditions of leakage from the metal waste container 11, groundwater containing radioactive nuclides passes through the bentonite buffer layer 13 and comes into contact with the inner liner layer 14. The metabolic activity of the fungi in the inner liner layer 14 is significantly enhanced due to the humid environment and radiation stimulation, triggering sensor warning and initiating active biosorption and nuclide fixation; The thickness ranges of the bentonite buffer layer 13 and the inner liner layer 14 are optimized and matched to ensure the matching of the two barriers in terms of physical thickness, so that the leaked nuclides can be promptly detected and responded to by the inner liner layer 14 after passing through the bentonite buffer layer 13, realizing the early warning function; At least one metabolic activity monitoring sensor 15 is embedded in the brick joints of the inner lining layer 14 and connected to a ground monitoring station via a radiation-resistant cable for monitoring the metabolic activity of fungi. The metabolic activity monitoring sensor 15 is an integrated multi-parameter sensor that can simultaneously detect three independent environmental parameters in the inner liner 14: CO2 concentration, relative humidity (RH), and temperature. Among them, the detection of CO2 concentration is used to reflect the respiratory metabolic intensity of melanin-producing fungi; the detection of relative humidity is used to provide early warning of groundwater intrusion and leakage events; and the detection of temperature is used to sense the active metabolism of microorganisms and changes in the local environment in real time. The metabolic activity monitoring sensor 15 can be implemented by integrating a CO2 electrochemical sensor or an NDIR CO2 sensor with a temperature and humidity sensor, or by using an NDIR CO2 sensor with integrated temperature and humidity compensation function.

[0041] This embodiment also provides a method for graded biological treatment and shielding of nuclear waste based on melanin-producing fungi. The system for graded biological treatment and shielding of nuclear waste based on melanin-producing fungi described above includes the following steps: 1. Radioactive wastewater purification stage: Radioactive wastewater generated during the operation of the nuclear power plant is pumped into radioactive wastewater storage tank 1 for temporary storage. According to the standard GB 9133-1996, "Classification of Radioactive Waste", the radioactive concentration of low-level radioactive waste liquid is ≤4×10⁻⁶. 6 Bq / L, radioactive concentration of medium-level radioactive waste liquid > 4 × 10⁻⁶ 6 Bq / L and ≤4×10 10 Bq / L.

[0042] The total α-radioactivity concentration of the radioactive wastewater described in this invention is <1×10⁻⁶. 5 Bq / L, total β radioactivity concentration <1×10 7 Bq / L covers the lower part of low-level and intermediate-level radioactive waste liquids, and belongs to the range of radioactive concentrations that can be directly treated by melanin-producing fungal mycelia. The radioactive wastewater described in this invention contains various radionuclides derived from fission products and corrosion activation products, mainly including... 137 Cs、 90 Sr and 60 One or more of Co; in one embodiment, 137 The radioactive concentration range of Cs is 1×10 2 ~1×10 5 Bq / L, 90 The radioactive concentration range of Sr is 1×10⁻⁶. 2 ~1×10 5 Bq / L, 60 The radioactive concentration range of Co is 1×10⁻⁶. 1 ~1×10 4 Bq / L; After purification treatment by fungal bioreactor 2, the radioactive concentration of the above-mentioned nuclides must meet the requirement in GB 6249-2011 "Regulations for Environmental Radiation Protection of Nuclear Power Plants" that the concentration of other radionuclides, except for tritium and carbon-14, at the inland plant site trough discharge outlet shall not exceed 100 Bq / L, and the total β radioactivity in the receiving water body 1 km downstream of the discharge outlet shall not exceed 1 Bq / L. It should be noted that the above-mentioned types and concentration ranges of radionuclides are descriptions of embodiments based on data of radioactive waste liquid sources from typical pressurized water reactor nuclear power plants in China. In practical applications, appropriate adjustments can be made according to the specific reactor type and operating conditions of the nuclear power plant. The radioactive wastewater in the radioactive wastewater storage tank 1 is pumped into the fungal bioreactor 2 at a flow rate of 0.5-2 times the volume of the fungal bioreactor 2 per hour, i.e., a flow rate of 0.5-2 BV / h, corresponding to a hydraulic retention time (HRT) of 0.5-2 h, and then flows downward through the mycelial packing layer 3. This flow rate range is based on a comprehensive optimization of the following three engineering constraints: (1) Upper limit control of flow rate, flow rate ≤ 2 BV / h, HRT ≥ 0.5 h: to prevent excessive fluid shear force from causing the mycelial balls or immobilized mycelium in the mycelial packing layer 3 to be washed away; Studies have shown that when HRT is less than 1.5 h, significant biomass scouring and loss occurs in the fungal bioreactor 2. This invention enhances the scouring resistance of mycelium in the form of immobilized or mycelial balls, but it is still necessary to control the flow rate below 2 BV / h to ensure the integrity of the mycelial packing layer 3 structure; (2) Lower limit control of flow rate: flow rate ≥ 0.5 BV / h, HRT ≤ 2 h: Ensure that the residence time of radioactive wastewater in the mycelial packing layer 3 does not exceed the critical time for complete consumption of dissolved oxygen, and ensure that aerobic conditions are maintained throughout the mycelial packing layer 3 so that the aerobic metabolism and "radioactive synthesis" effect of melanin-producing fungi can continue; if the flow rate With a concentration of 0.5 BV / h and an HRT of >2 h, the downstream of the mycelial packing layer 3 will form an anaerobic zone due to the depletion of dissolved oxygen, thus blocking the unique metabolic mechanism of fungi using radiation energy for self-enhanced adsorption. (3) Processing throughput guarantee: The lower limit of 0.5 BV / h ensures that the fungal bioreactor 2 has sufficient radioactive wastewater treatment capacity, making the present invention have engineering practical value. At the same time, the appropriate flow rate can prevent the excessive growth of fungal mycelium from causing bed blockage. After optimization, when the flow rate is 0.5-2 BV / h, it can ensure that the wastewater and mycelium are in full contact to achieve efficient radionuclide adsorption with a removal rate of ≥95%, while maintaining the aerobic metabolic activity and structural stability of the melanin-producing fungi in the entire packing layer, thus achieving the optimal balance between "adsorption efficiency, metabolic activity and biomass retention". While radioactive wastewater is sprayed into the fungal bioreactor 2, sterile air or sterile oxygen is introduced through an aeration device installed at the bottom inlet of the fungal bioreactor 2. The aeration device is located below the mycelial packing layer 3, and the air is evenly distributed from the bottom of the mycelial packing layer 3 upwards, so that the gas and liquid phases come into countercurrent contact in the gaps between the packing materials, thereby improving the oxygen mass transfer efficiency. The rising airflow also helps to slow down the compaction tendency of the mycelial packing layer 3 and promotes uniform contact between the mycelium and the radioactive wastewater. The dissolved oxygen concentration is controlled at 2~4 mg / L, that is, 25%~50% air saturation at normal temperature and pressure. This dissolved oxygen concentration range has the following three technical effects: (1) The lower limit ≥2 mg / L ensures that the entire mycelium packing layer 3 maintains aerobic conditions, ensuring the continuous aerobic metabolism and "radioactive synthesis" effect of melanin-producing fungi; (2) The upper limit is ≤4 mg / L to avoid excessive reactive oxygen species (ROS) generation caused by excessive dissolved oxygen, protect mycelial cells from oxidative stress damage, and maintain their long-term metabolic activity and genetic stability. (3) Matching the bottom aeration and mycelium packing layer 3 in height, a dissolved oxygen concentration gradient is formed from bottom to top. Radioactive wastewater is always in an aerobic microenvironment throughout the entire process of flowing through the mycelium packing layer 3, so as to achieve uniform aerobic metabolism of the mycelium packing layer 3 as a whole. In addition, the following key environmental parameters are controlled within fungal bioreactor 2 to ensure the healthy growth and metabolism of melanin-producing fungi: (1) The temperature is controlled at 25~30℃, which is the optimal growth temperature for most melanin-producing fungi and is consistent with the metabolic suitable temperature for the "radiosynthesis" effect; the temperature is automatically regulated by a jacketed water bath or an electric heating / cooling system. (2) The pH is controlled at 5.0~7.0. The weakly acidic environment is conducive to enhancing the electrostatic adsorption and complexation ability of the functional groups on the fungal cell wall to radioactive nuclide cations, and at the same time helps to inhibit the competitive growth of acid-intolerant bacteria; the pH is monitored by an online pH electrode and adjusted in real time by an automatic acid / alkali addition system. A low-speed mechanical stirring device is installed above the mycelium packing layer 3, with the stirring speed controlled at 50~100 r / min. The stirring device is located above the mycelium packing layer 3 rather than penetrating the interior of the mycelium packing layer 3, in order to avoid direct mechanical contact between the stirring blades and the mycelium packing, which could cause shear damage to the mycelium. The low-speed stirring of the stirring device achieves thorough mixing of the influent and the liquid phase in the fungal bioreactor 2, while limiting the fluid shear force to within the range that the mycelium can withstand. The stirring device and the aeration device complement each other: the aeration device is responsible for the supply of air or oxygen and the gas-liquid contact within the mycelium packing layer 3, while the stirring device is responsible for the macroscopic mixing of the liquid phase. The combined operation of the two can promote the homogenization of the concentration field and temperature field through mechanical stirring without increasing the aeration intensity, and achieve the optimal balance of "full mixing - low shear protection - efficient oxygen mass transfer". The highly efficient adsorption capacity of melanin-producing fungi for radionuclides stems from their unique multi-level structure and chemical composition: At the physical structure level, the melanin deposited in the cell walls of melanin-producing fungi exists in the form of melanin particles with a diameter of approximately 200 nm. These particles are assembled from melanin nanospheres with a diameter of approximately 30 nm, forming a multi-level nanostructure with an extremely high specific surface area. Simultaneously, the highly porous network formed by the interwoven hyphae further increases the effective adsorption area that can contact wastewater. At the chemical composition level, the cell walls and melanin of melanin-producing fungi contain abundant functional groups, mainly including hydroxyl –OH, carboxyl –COOH, amino –NH2, and phosphate –PO4. 3- One or more of these functional groups enable the efficient adsorption of radionuclides through the following mechanisms: (1) Electrostatic adsorption: Under weakly acidic conditions of pH 5.0~7.0, the carboxyl and phosphate groups on the cell wall surface undergo deprotonation and become negatively charged, thus adsorbing substances existing in the wastewater in the form of cations through electrostatic attraction. 137 Cs + , 90 Sr 2+ , 60 Co 2+ Radioactive nuclides; (2) Ion exchange: Protons H in functional groups such as carboxyl and hydroxyl groups on the cell wall + It can undergo exchange reactions with radioactive nuclide cations in solution, realizing the transfer of nuclides from the liquid phase to the solid phase; studies have shown that ion exchange is one of the important mechanisms in the adsorption of radioactive cesium and strontium by melanin-producing fungi. (3) Surface complexation / chelation: Functional groups such as hydroxyl, carboxyl, amino, and phosphate groups on the cell wall surface can form stable complexes or chelates with radioactive nuclide ions through coordination bonds, achieving irreversible chemical fixation; Studies have shown that the metal adsorption capacity per unit surface area of ​​dried biomass from melanin-producing fungi is 50 to 200 times higher than that of clay materials, fully demonstrating the efficient complexing ability of melanin functional groups, and the efficient physical adsorption and bio-enrichment of low-radioactive wastewater. 137 Cs + , 90 Sr 2 + , 60 Co 2+ Radioactive nuclides; More importantly, melanin in melanin-producing fungi is a biopolymer with a unique radiation response. When it adsorbs radionuclides, the energy of the gamma rays or beta particles emitted by the decay of the radionuclides is absorbed by the melanin, triggering the excitation and transition of electrons. The energy of these excited states is not entirely dissipated as heat, but is partially used to drive metabolic reactions within the cells of melanin-producing fungi, such as the synthesis of ATP. This phenomenon is called "radiosynthesis". This effect enables melanin-producing fungi to obtain additional energy sources in a radiation environment, promoting their growth and metabolic activity, thereby continuously maintaining or even enhancing their ability to adsorb radionuclides, forming a positive self-reinforcing purification mechanism. After purification treatment, the radioactive wastewater flows out through the effluent screen at the bottom of the fungal bioreactor 2, exits from the purified water outlet, and enters the subsequent monitoring tank. Once it meets the standards, it is either discharged or reused. Testing showed that the fungal bioreactor 2 effectively removed the main radionuclides from the radioactive wastewater as follows: [The text abruptly ends here, so the translation also ends here.] 137 Cs + The removal rate can reach over 95%, for 90 Sr 2+ The removal rate can reach over 90%, for 60 Co 2+ The removal rate can reach over 90% or 85%~95%, and the treated effluent meets the national discharge standards. It should be noted that the above removal rate data is based on the experimental results of the melanin-producing fungal mycelium packing layer under optimized fungal bioreactor 2 conditions. The adsorption efficiency of different nuclides may vary due to the types and concentrations of competing ions in the radioactive wastewater, the concentration of radioactive nuclides in the influent, the hydraulic retention time, and the different strains of melanin-producing fungi selected. In practical engineering applications, the above parameters can be optimized through conventional experiments to obtain the best removal effect for specific radioactive wastewater sources. 2. Waste Biomass Collection and Resource Utilization Stage: As operating time accumulates, the mycelium packing layer 3 will gradually become saturated. When the adsorption efficiency of the mycelium packing layer 3 is monitored to decrease, such as the removal rate of radionuclides decreasing by 15% to 20% compared with the initial value or the bed pressure drop increasing to 1.5 to 2 times the initial pressure drop, it indicates that the mycelium packing layer 3 is approaching saturation. At this point, close the inlet valve and open the backwash valve. Use purified water from an external purified water source to backwash and regenerate the mycelial packing layer 3. The backwash water flow rate is 2-5 times the normal treatment flow rate, and the backwash time is 3-8 minutes. The determination of this backwash flow rate range is based on comprehensive optimization of the following four aspects: (1) Ensuring effective expansion and regeneration: The backwash flow rate is ≥ 2 times the normal flow rate to ensure that the water flow generates sufficient drag force to fully expand the mycelial packing layer, promote mutual friction and collision between mycelial balls or immobilized mycelial particles, effectively remove the surface-saturated radionuclides and aging biofilm layer, and restore the adsorption active sites of mycelium; if the backwash flow rate is less than 2 times the normal flow rate, the bed expansion rate is <30%, the friction effect between particles is poor, the regeneration effect is insufficient, and the adsorption efficiency recovery rate is less than 80%; (2) Protection of mycelial structural integrity: Filamentous fungal mycelia are highly sensitive to fluid shear force. Backwashing flow rate > 5 times the normal flow rate will cause mechanical breakage of mycelia, disintegration of mycelial balls or detachment of immobilized mycelia from the carrier surface, resulting in a large loss of biomass. Laboratory studies have confirmed that moderate shear force can promote mass transfer and metabolism, but excessive shear force will cause mycelial breakage and fracture, affecting the morphology and growth rate of organisms. Controlling the backwashing flow rate to within 5 times the normal flow rate can ensure that only the aging waste mycelia on the surface of the packing layer are peeled off, while the structural integrity of the core mycelia with high metabolic activity is preserved, achieving "selective renewal" at the biofilm level. The adsorption efficiency can be restored to more than 90% of the initial level in a short time after backwashing. (3) Synergistic optimization of biomass recycling quality: The gentle backwash flow rate ensures that the discharged waste fungal biomass maintains a relatively complete mycelial morphology and structure, rather than fragmentation. This is beneficial for thorough and uniform mixing with the matrix material in the subsequent composite shielding brick preparation steps, and for the formation of a mycelial network through the regrowth of residual mycelia during the brick curing period to enhance the strength of the brick. If the flow rate is too high, it will cause excessive fragmentation of mycelia, which will reduce the structural integrity and strength of the subsequent bricks. (4) Matching with the form of mycelial immobilization: When the mycelium exists in the form of mycelial balls, the backwashing flow rate should be controlled at 2-3 times the normal flow rate. The friction between the mycelial balls can effectively achieve the peeling of the surface biofilm. When the mycelium is fixed on a porous carrier, a flow rate of 3-5 times the normal flow rate can be selected. The impact force of the higher flow rate can overcome the binding force between the immobilized mycelium and the carrier to achieve effective regeneration. At the same time, the mechanical support provided by the carrier can protect the mycelium from damage caused by excessive shear force. After backwashing is complete, close the backwash valve and let it stand for 3-5 minutes to allow the mycelium to settle naturally and restore the packing layer structure. Then reopen the inlet valve and resume normal wastewater treatment operation. The backwash liquid carries the waste fungal biomass into the waste fungal biomass collector 5; to prevent the waste fungal biomass from decaying, the waste fungal biomass collector 5 is kept at a low temperature of 4°C; the collected waste fungal biomass has a water content of 80-90% and the radioactivity in its dry weight is thousands of times that of the initial radioactive wastewater, achieving high concentration; Next, the waste fungal biomass (dry weight) and the matrix material from the matrix material silo 6 are fed into the mixing mixer 7 via a screw conveyor and a metering conveyor belt at a mass ratio of 1:1 to 1:3. Purified water, accounting for 10% to 15% of the total dry mass of the waste fungal biomass and matrix material, is added, and the mixture is stirred at a speed of 30 to 60 r / min for 15 to 25 minutes, preferably 20 minutes, to form a homogeneous mixture with good plasticity. The parameters of water addition, stirring speed, and stirring time are optimized based on the following three aspects: (1) Optimization of water addition: The moisture content of the waste fungal biomass after backwashing is 80%~90%. It carries a large amount of water. Adding 10%~15% purified water is not the main factor determining the total moisture content of the mixture. Its core function is to replenish the water lost due to evaporation and mixing during the stirring process, adjust the plasticity of the mixture to achieve the best pressing state, and provide an initial moist environment for the regeneration of residual mycelium in the subsequent curing stage. Adding at least 10% purified water ensures that the substrate material is fully wetted to achieve uniform mixing and provides the necessary moisture conditions for mycelial regrowth during the maintenance phase. Studies have shown that a water content of 70% in solid culture substrate is the critical threshold for fungal mycelial growth; above 70% can promote growth, while below 55% growth stops. Adding less than 15% purified water prevents the mixture from bleeding during pressing, softening of the structure during curing, and cracking of the brick due to excessive moisture content, while also avoiding weakening of mechanical strength due to reduced matrix density. (2) Optimization of stirring speed: Filamentous fungal mycelium is highly sensitive to shear force. Excessive speed will cause mycelium to break and fragment, significantly reducing the ability of residual mycelium to regenerate and form an enhanced mycelial network during the curing stage. Studies have shown that under high stirring intensity, more than 98% of mycelium is small mycelial balls with slow growth rate; while excessive stirring and aeration may cause mycelium to break. Filamentous fungi are highly sensitive to the shear force generated by different types of agitators. Selecting a suitable agitator can reduce hyphal breakage, improve growth, and increase enzyme production by 54%. The low speed design of 30~60 r / min controls the shear force within the range that the mycelium can withstand, while adapting to the high viscosity and paste-like physical properties of the mixture, ensuring effective agitation of the agitator and mixing of the mixture, achieving the dual goals of uniform mixing and protection of mycelial activity. (3) Optimization of mixing time: The mixing time needs to take into account both the uniformity of mixing and the protection of mycelial shear. If the time is too short, the mycelium and matrix particles in the mixture cannot fully contact and disperse evenly, resulting in uneven internal composition of the brick blank after pressing and molding, which affects the overall mechanical properties and radiation shielding effect of the brick. If the time is too long, the cumulative shear stress borne by the mycelium will exceed its tolerance limit, causing irreversible mycelial breakage and loss of activity, weakening the formation ability of the mycelial network during the curing stage. Studies have shown that there is a direct positive correlation between the matrix density and mechanical strength of mycelial composite materials, while the cultivation time is inversely related to the mechanical properties. The mixing time is 15~25 minutes, preferably 20 minutes, so that the mixture can achieve the best plasticity and uniformity while maximizing the preservation of the structural integrity and metabolic activity of the mycelium. The mixture is then fed into a compression molding machine 8 and cold-pressed under a pressure of 20-30 MPa to form a matrix-fungus composite shielding brick 9; the compression pressure range of 20-30 MPa is optimized based on the following technology: (1) Densification and enhanced shielding performance: Studies have shown that pressing can significantly reduce the porosity of mycelial composite materials and densify them, thereby improving mechanical properties; increasing pressure helps to reduce the porosity of bricks, increase the density of melanin produced by melanin-producing fungi and inorganic shielding elements such as Si, Al, and Fe in the matrix material per unit volume, thereby enhancing the attenuation ability of bricks against γ-rays and the moderation effect on neutrons. (2) Lower limit constraint: Ensure that the mycelium and matrix particles in the mixture are fully compressed to the target density, and remove excess air and some moisture, so as to provide close particle contact conditions for the formation of mycelial network and the hydration reaction of inorganic cementitious materials during the curing stage. (3) Upper limit constraint: Based on two technical considerations, firstly, excessive pressure will squeeze out too much water needed to maintain metabolic activity in the mycelium, affecting the regrowth of residual mycelium and the effect of mycelial network enhancement during the curing stage; secondly, excessive pressure may cause soft matrix particles such as bentonite to be excessively crushed, which will reduce the overall structural stability and uniformity of the bricks. (4) Synergistic advantages of cold pressing process: Compared with hot pressing process, cold pressing process avoids thermal damage to mycelial activity caused by high temperature and preserves the metabolic potential of residual mycelium to grow again during maintenance. This is a necessary prerequisite for achieving the "maintenance enhancement" effect, that is, the construction of mycelial network. The molded matrix-fungus composite shielding brick 9 was cured for 7 days at a temperature of 25±3℃ and a relative humidity of 85±5%; these curing conditions are based on the optimal physiological requirements for fungal mycelial growth. (1) Temperature 25±3℃: The optimal growth temperature for most melanin-producing fungi and common fungi mycelia is around 25℃. At this temperature, the respiratory metabolism and tip extension rate of the mycelia are at the optimal level, which is conducive to the rapid construction of the mycelial network during the maintenance period. If the temperature is below 20℃, the mycelial growth rate will slow down significantly, and a sufficient reinforcing network cannot be formed within 7 days. If the temperature is above 30℃, the mycelial metabolism will be too fast and the nutrient consumption will be too large, which may lead to premature aging or even autolysis of the mycelia, affecting the reinforcing effect. (2) Relative humidity 85±5%: A curing humidity of 85±5% can effectively inhibit the evaporation loss of moisture inside the brick blank, provide sufficient moisture conditions for the regeneration of residual mycelium, and at the same time avoid liquid water condensation and oxygen diffusion obstruction caused by excessive humidity. (3) Curing time: 7 days. Fungal mycelium can fully colonize and penetrate the substrate within 5-7 days. The 7-day curing time ensures the full construction of the mycelial network while taking into account production efficiency, avoiding problems such as excessive mycelial growth, nutrient depletion, and accumulation of metabolic byproducts that may occur with long-term curing. During the curing period, the remaining melanin-producing fungal mycelium can regrow and form a dense mycelial network. The chitin secreted by the mycelium, which has a tensile strength comparable to that of carbon fiber, firmly wraps and adheres the substrate particles together. At the same time, the inorganic cementing components in the substrate material, such as cement and gypsum, undergo hydration reactions with water to form independent inorganic bonding strength. The physical wrapping of the mycelial network and the chemical solidification of the inorganic bonding constitute a "biological-inorganic dual reinforcement mechanism," which significantly improves the compressive strength of the bricks. After 7 days of curing, the compressive strength of the bricks can reach 15-20 MPa. 3. Application and monitoring phase of deep geological repositories: In the deep geological treatment facility 12, the metal waste container 11 containing the high-level radioactive waste glass solidifier 10 is placed in place; A bentonite buffer layer 13 is filled around the metal waste tank 11. An inner lining layer 14 is constructed around the bentonite buffer layer 13 using matrix-fungus composite shielding bricks 9. During construction, metabolic activity monitoring sensors 15 are embedded in the brick joints of the inner lining layer 14. The metabolic activity monitoring sensors 15 are integrated multi-parameter sensors capable of simultaneously detecting three independent environmental parameters in the inner lining layer 14: CO2 concentration, relative humidity, and temperature. CO2 concentration detection reflects the respiratory metabolic intensity of melanin-producing fungi in the inner lining layer 14; relative humidity detection provides early warning of local humidity anomalies caused by leaks in the metal waste tank 11; and temperature detection is used to sense real-time changes in ambient temperature caused by active microbial metabolic heat production and leaks. Simultaneous monitoring of these three parameters enables cross-validation and synergistic early warning: an abnormal increase in CO2 concentration combined with a synchronous increase in local humidity indicates fungal metabolic activation caused by groundwater intrusion; any single abnormality or a combination of abnormalities in multiple parameters can trigger an early warning, effectively reducing the false alarm rate. During long-term monitoring after the deep geological treatment reservoir 12 was sealed, most of the fungi in the inner lining layer 14 were in a dormant or slow endogenous state, and their metabolic activity remained at an extremely low level. The fungal melanin and biomass organic components in the inner lining layer 14 can effectively scatter and absorb gamma rays and have a certain slowing effect on neutrons. Together with concrete and bentonite, they enhance the overall shielding effect. Once the metal waste container 11 leaks due to corrosion, the groundwater containing radioactive nuclides will first pass through the bentonite buffer layer 13 and come into contact with the inner liner 14. At this time, the fungi surviving in the inner liner 14 will germinate rapidly due to contact with the humid environment and the stimulation of the new radiation source, and the mycelium will resume active metabolism. During this process, the CO2 production rate will increase significantly, and the local temperature and humidity will also change. These changes are captured in real time by the embedded metabolic activity monitoring sensor 15 and converted into electrical signals and transmitted to the ground monitoring center. The system will issue an early warning, indicating that there may be a risk of radionuclide leakage in the deep geological disposal repository 12. More importantly, the active fungal hyphae network will once again exert its bioadsorption function, actively adsorbing and fixing the radionuclides leaking from the damage site, trapping them in the inner liner 14 and preventing them from migrating to the external environment; this bioactive response mechanism endows the originally static engineering barrier with an intelligent "sensing-response-repair" characteristic, which is unmatched by traditional passive barriers.

[0043] This invention constructs a closed-loop system for nuclear waste treatment through three closely coupled links: "biological purification of wastewater, resource utilization of waste biomass, and construction of active biological barriers".

[0044] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A nuclear waste fractionating bioprocessing and shielding system, characterized by, include: Radioactive wastewater storage tank (1) is used to temporarily store radioactive wastewater generated during the operation of a nuclear power plant; The fungal bioreactor (2) has a first inlet at the top connected to the outlet of the radioactive wastewater storage tank (1); a second inlet at the top connected to an external purified water source; an aeration device is installed at the bottom inlet; a purified water outlet and a biomass outlet (4) are provided at the bottom; a mycelium packing layer (3) composed of mycelium of non-pathogenic, highly radiation-tolerant melanin-producing fungi is installed inside; and a stirring device is installed above the mycelium packing layer (3) inside. The waste fungal biomass collector (5) has its inlet connected to the biomass outlet (4) of the fungal bioreactor (2); Matrix material bin (6); The mixing agitator (7) has its first inlet connected to the outlet of the waste fungal biomass collector (5) and its second inlet connected to the outlet of the matrix material bin (6); The inlet of the compression molding machine (8) is connected to the outlet of the mixing agitator (7); The deep geological disposal facility (12) is equipped with a metal waste tank (11) for loading high-level radioactive waste glass solidifier (10). The metal waste tank (11) is surrounded by a bentonite buffer layer (13) and an inner lining layer (14) made of matrix-fungus composite shielding bricks (9). At least one metabolic activity monitoring sensor (15), which is an integrated multi-parameter sensor, is embedded in the inner liner (14).

2. The nuclear waste graded biological treatment and shielding system according to claim 1, characterized in that, The bulk density of the mycelium packing layer (3) is 50~150 g dry weight / L packing volume, and the specific oxygen consumption rate of the melanin-producing fungal mycelium at 25~30℃ is 0.5~2.0 mg O2 / (g dry weight·h). The mycelium in the mycelium packing layer (3) exists in the form of mycelium balls or is attached to the porous carrier in an immobilized manner; when the mycelium exists in the form of mycelium balls, the diameter of the mycelium balls is 1~10 mm; when the mycelium is attached to the porous carrier in an immobilized manner, the porous carrier is polyvinyl alcohol compounded with sodium alginate or polyurethane foam. The filling height of the mycelium packing layer (3) is 1 / 2 to 2 / 3 of the effective height of the fungal bioreactor (2).

3. The nuclear waste fractionating bioprocessing and shielding system of claim 1, wherein, Non-pathogenic, highly radiation-resistant melanin-producing fungi were obtained through screening and / or domestication using the following methods: (1) Selection of starting strain: Melanin-producing fungi with radiation tolerance were selected as starting strains. The starting strains were identified or genetically modified to be non-pathogenic or low-pathogenic strains. (2) Adaptive laboratory evolution: The starting strain was inoculated into a liquid culture medium containing a gradient concentration of radionuclides, with the radioactivity concentration ranging from 10... 2 Bq / mL gradually increased to 10 5 Continuous subculturing was carried out under the condition of Bq / mL, with each generation lasting 7-14 days and a total of no less than 10 generations. This allowed the fungi to accumulate adaptive mutations to the high-radiation environment under continuous selection pressure, resulting in the domesticated fungal population. (3) Screening of highly tolerant strains: The domesticated bacterial population was spread on solid culture medium plates and cultured for 7 to 14 days under γ-ray or X-ray irradiation with a dose rate of 10 to 100 Gy / h. Single colonies with normal growth and significant melanin phenotype were selected. The selected colonies were exposed to γ-ray irradiation with increasing doses and the survival rate of each strain was determined. Mutants with a half-lethal dose ≥ 1.0 kGy or a survival rate significantly higher than that of the starting strain at the target dose were selected as non-pathogenic, highly radiation-tolerant melanin-producing fungal strains.

4. The nuclear waste fractionating bioprocessing and shielding system of claim 1, wherein, The matrix material is one or more of bentonite, gypsum, cement or biodegradable polymer; the radial thickness of the bentonite buffer layer (13) is 30~50 cm, and the bentonite is high-pressure sodium-based bentonite; the masonry thickness of the inner lining layer (14) is 20~50 cm.

5. The nuclear waste fractionating bioprocessing and shielding system according to claim 1, wherein, The fungal bioreactor (2) is equipped with a water distributor at the top inlet and an outlet screen at the purified water outlet.

6. A method of graded biological treatment and shielding of nuclear waste material, characterized by, The system for graded biological treatment and shielding of nuclear waste according to any one of claims 1-5 includes the following steps: S1. Pump the radioactive wastewater in the radioactive wastewater storage tank (1) into the fungal bioreactor (2) so that it flows through the mycelial packing layer (3). At the same time, start the stirring device and the aeration device. The aeration device introduces sterile air or sterile oxygen into the fungal bioreactor (2), and the stirring device promotes the mixing of fluids in the fungal bioreactor (2). Melanin-producing fungi absorb the ionizing radiation released by radionuclides in radioactive wastewater and convert it into chemical energy required for mycelial growth and metabolism through radiosynthesis, thereby achieving the bioadsorption, enrichment and purification of radionuclides. S2. When the mycelium packing layer (3) is saturated with adsorption, the waste fungal biomass is transported to the waste fungal biomass collector (5) by backwashing or direct discharge. S3: The waste fungal biomass in the waste fungal biomass collector (5) and the matrix material in the matrix material bin (6) are put into the mixing mixer (7) according to a predetermined mass ratio. After adding purified water and stirring evenly to form a mixture, it is sent to the pressing and molding machine (8) to be pressed into a matrix-fungus composite shielding brick (9) and cured. S4: In the deep geological treatment facility (12), after the metal waste tank (11) containing the high-level radioactive waste glass solidifier (10) is placed in place, a bentonite buffer layer (13) is filled around it, and an inner lining layer (14) is built around the buffer layer using matrix-fungus composite shielding bricks (9), while a metabolic activity monitoring sensor (15) is embedded in the inner lining layer (14). S5: The three parameters of CO2 concentration, relative humidity and temperature in the inner lining layer (14) are detected simultaneously and in real time by the metabolic activity monitoring sensor (15). When a single parameter or a combination of multiple parameters is abnormal, it is determined that the metabolic activity of melanin-producing fungi is abnormal, triggering a radionuclide leakage warning.

7. The method of graded biological treatment and shielding of nuclear waste material according to claim 6, characterized in that, In S1, the radioactive wastewater in the radioactive wastewater storage tank (1) is pumped into the fungal bioreactor (2) from the top inlet of the fungal bioreactor (2) at a flow rate of 0.5-2 times the volume of the fungal bioreactor (2) per hour, and flows downward through the mycelial packing layer (3); the dissolved oxygen concentration in the fungal bioreactor (2) is controlled at 2~4 mg / L, the temperature is controlled at 25~30℃, and the pH is controlled at 5.0~7.0; the stirring speed of the stirring device is controlled at 50~100 r / min.

8. The method of graded biological treatment and shielding of nuclear waste material according to claim 6, wherein, In S2, when the radionuclide removal rate of the mycelium packing layer (3) is found to be 15% to 20% lower than the initial value or the bed pressure drop is increased to 1.5 to 2 times the initial pressure drop, the mycelium packing layer (3) is backwashed and regenerated using purified water from an external purified water source; the flow rate of the purified water during backwashing is 2 to 5 times the normal influent flow rate, and the backwashing time is 3 to 8 minutes. The temperature inside the waste fungal biomass collector (5) is maintained at 4℃, and the collected waste fungal biomass has a moisture content of 80-90%.

9. The method for graded biological treatment and shielding of nuclear waste according to claim 6, characterized in that, In S3, the waste fungal biomass in the waste fungal biomass collector (5) and the matrix material in the matrix material bin (6) are put into the mixing mixer (7) at a mass ratio of 1:1 to 1:

3. 10% to 15% of the total mass of the waste fungal biomass and matrix material is added to purified water. The mixture is stirred at a speed of 30 to 60 r / min for 15 to 25 minutes to form a mixture.

10. The method of nuclear waste fractionation biological treatment and shielding according to claim 6, wherein, In S4, the pressing molding machine (8) cold-presses the mixture into a matrix-fungus composite shielding brick (9) under a pressure of 20~30 MPa; the matrix-fungus composite shielding brick (9) is cured for 7 days at a temperature of 25±3℃ and a relative humidity of 85±5%.

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