A method for treating complex component radioactive liquid waste

Abstract

The present application relates to a kind of complex component radioactive waste liquid processing method, steps are as follows: organic matter is contained in waste liquid and sodium hydroxide and sucrose solution is added to pretreat and carry out oxidation decomposition treatment;pH value is adjusted, steam heating is carried out, ammonia in waste liquid is recycled under the condition of high gravity state and is rotated and separated, and after the pH value of deamination waste liquid is adjusted, it is input into first reverse osmosis unit, and is concentrated in circulation, and the concentrated first concentrated phase is carried out rotary evaporation and crystallization, and waste liquid steam and first dilute phase are sent to second reverse osmosis unit and are concentrated in circulation, and the obtained second concentrated phase is recycled;Second dilute phase is discharged or it is input into reverse osmosis+EDI unit and is deeply treated and reused.The present application designs the process flow of preferentially treating waste liquid containing organic matter, and then treating waste liquid not containing organic matter, forms simple and efficient process route;With the advantages of efficient and clear, purification is thorough, easy to operate, simple and reliable, effectively solve the purification treatment problem of complex component radioactive waste liquid.

Description

Technical Field

[0001] This invention belongs to the field of radioactive waste treatment technology, specifically relating to a method for treating radioactive waste liquid with complex components. Background Technology

[0002] Currently, my country has formed a relatively complete nuclear industry system. However, with the development of nuclear energy, the total amount of radioactive waste generated and accumulated is constantly increasing. The capacity for radioactive waste disposal is not commensurate with the development of nuclear energy, and the safety, social, and environmental problems caused by the over-storage of waste are becoming increasingly prominent. Existing technologies can effectively treat waste liquids with single components or small amounts of simple mixtures, such as radioactive waste liquids, ethanol-containing waste liquids, methanol-containing waste liquids, ammonia-containing waste liquids, and inorganic salt-containing waste liquids, all of which have relatively mature technologies. However, in the treatment of complex radioactive waste liquids (where radionuclides, organic components, and inorganic salts coexist in high concentrations), due to limitations in treatment technology and economic factors, in actual production processes, temporary treatment methods of classified storage are often used to treat large quantities of complex waste liquids, without fundamentally solving this problem.

[0003] The main reasons why complex radioactive waste liquid cannot be effectively treated are: (1) Ethanol and ammonia are both volatile, and ammonia needs to be recycled. When treating ethanol, ammonia will affect the treatment effect; when ammonia is mixed with formaldehyde, hexamethylenetetramine will be generated. When the three coexist, a dynamic equilibrium will occur, which will also affect the application of existing treatment technologies. (2) Organic matter is easily oxidized, and organic matter (ethanol, hexamethylenetetramine or formaldehyde) is oxidized by oxidation. However, when faced with waste liquid with such high chemical oxygen demand (COD), chemical oxidation consumes too many reagents, is not effective, and is not economically viable; biological oxidation cannot treat such high concentrations of organic waste liquid; photocatalytic oxidation is less efficient and is only suitable for the catalytic oxidation of low concentration organic waste liquid; electrochemical catalytic oxidation results are not ideal, and a large amount of hydrogen and other byproducts will be generated during the treatment process, posing an explosion risk. Therefore, the current oxidation methods cannot meet the treatment requirements. (3) Another method is to separate organic matter from water. Because hexamethylenetetramine and ethanol are present in the waste liquid, and hexamethylenetetramine is stable under alkaline conditions, ammonia and ethanol can be separated by distillation or gravity. After separating ammonia and ethanol, the waste liquid is left with hexamethylenetetramine, sodium nitrite and sodium nitrate. Evaporate, crystallize and dry them to obtain a mixed solid of the three, which is then disposed of as extremely low radioactive waste. However, at this time, the secondary steam condensate contains ethanol and ammonia, which need to be treated by conventional technology. The whole process system is very cumbersome and complex, and its practical applicability is not high.

[0004] For radioactive waste liquids with complex compositions, the treatment is challenging due to the mixture of various organic substances and the difficulty in separating the components. Traditional technologies are largely unsuitable. Furthermore, the presence of high salt content, formaldehyde, ammonia, and other components hinders the application of more versatile technologies such as biological methods, resulting in a limited range of available technologies. Previously, such complex mixed waste liquids were treated through temporary storage, and no effective treatment technologies or case studies have been found to date. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to propose a method for treating complex radioactive waste liquid. Specifically, it is a complete process route for treating complex radioactive waste liquid from a new nuclear fuel element production line. It is applied to the systematic purification and treatment of radioactive waste liquid containing high concentrations of various organic substances, ammonia, ammonium salts, sodium salts and other complex components generated during the production of a new type of nuclear fuel.

[0006] The technical solution of this invention is:

[0007] A method for treating radioactive waste liquid with complex components includes the following steps:

[0008] (1) Add sodium hydroxide solution to the waste liquid containing organic matter and adjust the pH value to 8-9, then add sucrose solution for pretreatment, and carry out oxidative decomposition treatment at a pressure of 15-25 MPa and a temperature of 450-650℃. The treated water is mixed with the waste liquid without organic matter to obtain a mixed waste liquid.

[0009] The pressure in step (1) is 15–25 MPa, for example, it can be 15 MPa, 16 MPa, 17 MPa, 19 MPa, 20 MPa, 22 MPa, 23 MPa, 24 MPa or 25 MPa, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. The temperature is 450–650℃, for example, it can be 450℃, 470℃, 480℃, 500℃, 530℃, 550℃, 600℃, 620℃, 630℃, 635℃, 640℃, 645℃ or 650℃, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0010] (2) Adjust the pH value of the mixed waste liquid to 10.5-11.5, and then heat it with steam at 110-120 kg / h and 105-115℃. Under hypergravity, rotate to separate the ammonia in the waste liquid. When the mass concentration of ammonia water is ≥20%, it is recycled. The deammoniation waste liquid is cooled with water at 7℃.

[0011] The steam heating conditions in step (2) are 110–120 kg / h, for example, 110 kg / h, 112 kg / h, 115 kg / h, 117 kg / h, 118 kg / h, 119 kg / h, or 120 kg / h, but are not limited to the listed values. Other unlisted values ​​within this range are also applicable. The temperature is 105–115℃, for example, 105℃, 107℃, 108℃, 109℃, 110℃, 111℃, 112℃, 113℃, or 115℃, but are not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0012] (3) After adjusting the pH value of the deammoniation waste liquid to 8-9, the waste liquid is fed into the first-stage reverse osmosis unit. The waste liquid is circulated and concentrated using a spiral-wound polyamide membrane with a pressure resistance of 1800 PSI and a desalination rate of more than 99.7%. After concentration, a first-stage concentrated phase and a first-stage dilute phase are obtained.

[0013] (4) The primary concentrated phase is subjected to rotary evaporation and crystallization under steam heating conditions of 120-150 kg / h and 105-115℃ to collect inorganic salt crystals. The waste liquid vapor generated by evaporation is cooled by water condensation at 7℃ and sent to the secondary reverse osmosis unit along with the primary desalted phase. The unit uses an aromatic polyamide composite membrane with a pressure resistance of 1000 PSI and a desalination rate of over 99% for circulation concentration to obtain the secondary concentrated phase and the secondary desalted phase. The secondary concentrated phase is returned to the primary reverse osmosis unit for circulation treatment.

[0014] The steam heating conditions in step (4) are 120–150 kg / h, for example, 120 kg / h, 125 kg / h, 130 kg / h, 135 kg / h, 140 kg / h, 145 kg / h, 146 kg / h, 147 kg / h, 148 kg / h, 149 kg / h, or 150 kg / h, etc., but not limited to the listed values; other unlisted values ​​within this range are also applicable. The temperature is 105–115℃, for example, 105℃, 107℃, 108℃, 109℃, 110℃, 111℃, 112℃, 113℃, or 115℃, etc., but not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0015] (5) Discharge the secondary light phase from step (4) or input it into the reverse osmosis + EDI unit for deep treatment and reuse.

[0016] Furthermore, the reverse osmosis + EDI treatment step in step (5) includes: inputting the secondary desalinated phase into the reverse osmosis + EDI unit. The reverse osmosis unit uses an aromatic polyamide composite membrane with a pressure rating of 450 PSI and a desalination rate of over 99%. The EDI unit uses an electro-deionization module with a product water resistivity of 16.0 to 18.2 MΩ·cm and a recovery rate of 90% to 99%, so that the final product water conductivity is reduced to below 0.1 μS / cm (25℃).

[0017] Furthermore, the concentrated water from the reverse osmosis + EDI unit is returned to the secondary reverse osmosis unit for recycling.

[0018] Furthermore, the complex-component radioactive waste liquid includes waste liquid containing organic matter and waste liquid without organic matter.

[0019] Furthermore, in step (1), the waste liquid containing organic matter is input into the supercritical water oxidation unit, and 20wt% to 40wt% sodium hydroxide solution is added to adjust the pH value to 8 to 9; according to the organic matter content in the waste liquid, 40wt% to 80wt% sucrose solution is added for pretreatment, and under the combined action of 25MPa pressure, 650℃ temperature and saturated oxygen, the organic components in the waste liquid are oxidized and decomposed, so that the COD of the produced water is reduced to below 80mg / L, and the produced water is mixed with the waste liquid without organic matter.

[0020] The amount of sodium hydroxide solution added is 20wt% to 40wt%, for example, 20wt%, 22wt%, 25wt%, 27wt%, 29wt%, 30wt%, 33wt%, 35wt%, 37wt%, or 40wt%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. The amount of sucrose solution added is 40wt% to 80wt%, for example, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 62wt%, 65wt%, 70wt%, 750wt%, or 80wt%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0021] Furthermore, 30wt% sodium hydroxide solution was added to adjust the pH to 8, and 60wt% sucrose solution was added for pretreatment based on the organic matter content in the waste liquid.

[0022] Furthermore, in step (2), 20wt% to 40wt% sodium hydroxide solution is added to adjust the pH value of the mixed waste liquid to 11, so that all the ammonium ions in the waste liquid are converted into ammonia; then, the waste liquid is heated by 120kg / h, 110℃ steam, and the ammonia in the waste liquid is separated by rotation under hypergravity. When the mass concentration of ammonia water is ≥20%, it is recovered, and the deammoniation waste liquid is cooled by 7℃ low temperature water.

[0023] Furthermore, in step (3), after the pH value of the deammoniation waste liquid is adjusted to 8, it is input into the first-stage reverse osmosis unit. The waste liquid is circulated and concentrated using a spiral-wound polyamide membrane with a pressure resistance of 1800 PSI and a desalination rate of 99.7%. The resulting first-stage concentrated phase and first-stage dilute phase are stored separately.

[0024] Furthermore, in step (4), the primary concentrated phase is subjected to rotary evaporation and crystallization under steam heating conditions of 150 kg / h and 110°C. The collected inorganic salt crystals with a water content of 5% to 8% (approximately 7%) are transported and temporarily stored. The waste liquid vapor generated by evaporation is cooled by water condensation at 7°C and sent to the secondary reverse osmosis unit along with the primary desalinated phase. The unit uses an aromatic polyamide composite membrane with a pressure resistance of 1000 PSI and a desalination rate of 99% for circulation concentration to obtain the secondary concentrated phase and the secondary desalinated phase. The secondary concentrated phase is returned to the primary reverse osmosis unit for circulation treatment.

[0025] Based on the characteristics of the waste liquid, this invention first uses supercritical water oxidation technology to treat the organic components in the waste liquid containing organic matter. This treated waste liquid is then combined with the organic-free waste liquid to form a single stream. Ammonia is removed and recovered from the waste liquid using ultragravity deammoniation technology. Next, a three-stage reverse osmosis combined with electro-deionization technology is used for desalination and deep purification. The treated waste liquid can be reused as production water on the production line. For the concentrated waste liquid generated in this process, membrane evaporation crystallization technology is used to convert it into solid crystals, which are then collected and centrally disposed of. The technical nodes in the entire process complement each other, forming a closed loop of treatment—disposal / reuse.

[0026] The beneficial effects of this invention are:

[0027] (1) Based on the characteristics of the waste liquid, a process flow was designed to prioritize the treatment of waste liquid containing organic matter, and then combine the treatment of waste liquid without organic matter. The organic and inorganic waste liquids are treated on the same line, forming a simple and efficient process route. Compared with the method of treating organic and inorganic waste liquids separately, it has the advantages of high efficiency, clear treatment, thorough purification, convenient operation, and simple reliability. It can effectively solve the problem of purification treatment of waste liquid generated by a certain new fuel element production line.

[0028] (2) This invention uses supercritical water oxidation technology to treat high COD waste liquid containing organic matter (high COD waste liquid generally refers to waste liquid with chemical oxygen demand COD higher than 2000 mg / L); it uses supergravity deammoniation technology to remove ammonia from the waste liquid and form ammonia water of the required concentration for recovery, which can realize the recycling and reuse of ammonia water and improve economic efficiency.

[0029] (3) A combination of three-stage reverse osmosis and electrodialysis technology was adopted to deeply purify this type of waste liquid, so that the waste liquid was finally treated to far exceed the emission standards and reach the standard of "reuse", so that the treated waste liquid could be reused as production water, and the "near-zero discharge" of waste liquid treatment was basically achieved.

[0030] (4) The membrane evaporation crystallization technology is adopted to directly crystallize the concentrate produced by the reverse osmosis unit into solid salts, which simplifies the concentrate treatment process. The final product of the waste liquid is a partially solid inorganic salt, which truly realizes the principle of "minimizing waste". Attached Figure Description

[0031] Figure 1 A schematic diagram of the process flow for the treatment method of complex radioactive waste liquid provided by the present invention. Detailed Implementation

[0032] 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 embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] To further understand the present invention, it will be further described in conjunction with the accompanying drawings and embodiments.

[0034] In a domestic production line for a new type of nuclear fuel element, organic compounds including ethanol, formaldehyde, isooctanol, sulfonated kerosene, and tributyl phosphate are introduced into the fuel production process. Therefore, during the production of this fuel element, auxiliary materials generate waste liquid containing these organic compounds and waste liquid without organic compounds. Among them:

[0035] The main components of the waste liquid containing organic matter are: water, radioactive nuclides (ammonium diuranate), organic components (ethanol, formaldehyde, isooctanol, tributyl phosphate, sulfonated kerosene), inorganic salts (ammonium nitrate, sodium nitrate, sodium nitrite), and ammonia.

[0036] The main components of the organic-free waste liquid are: water, radioactive nuclides (ammonium diuranate), inorganic salts (sodium nitrite, sodium nitrate, ammonium nitrate, sodium chloride, ammonium fluoride), and ammonia.

[0037] This type of waste liquid containing organic matter has a low uranium concentration, a pH value of 7-8, contains a large amount of water-soluble organic matter, a small amount of insoluble organic matter, and a COD ≥ 1×10⁻⁶. 5mg / L, and contains ammonia, ammonium salts, sodium salts, etc.; the organic waste liquid has low uranium concentration, pH value 9-10, nitrate nitrogen about 3800 mg / L, sodium salt about 27000 mg / L, and contains ammonia, ammonium salts, etc.

[0038] Example 1

[0039] like Figure 1 As shown, this embodiment designs and provides a method for treating complex radioactive waste liquid (containing organic waste liquid and non-organic waste liquid) generated by the above-mentioned novel nuclear fuel element production line, including the following steps:

[0040] (1) Waste liquid containing organic matter and waste liquid not containing organic matter shall be stored in corresponding organic waste liquid storage tanks and inorganic waste liquid storage tanks, respectively. The volume of the organic waste liquid storage tank is 8m³. 3 Inorganic waste liquid storage tank with a volume of 5m³ 3 ;

[0041] Supercritical water oxidation: Wastewater containing organic matter is fed into the supercritical water oxidation unit, and 30wt% sodium hydroxide solution is added to adjust the pH to 8.5. Based on the organic matter content in the wastewater, 60wt% sucrose solution is added for pretreatment. Under the combined action of 25MPa pressure, 650℃ temperature, and saturated oxygen, the organic components in the wastewater are oxidized and decomposed, reducing the COD of the produced water to below 80mg / L. The produced water is then output to an inorganic wastewater storage tank to obtain mixed wastewater. The tail gas generated by the system is absorbed by the recycled production water. The unit treatment capacity is 100L / h.

[0042] (2) pH adjustment: Add 30wt% sodium hydroxide solution to adjust the pH of the mixed waste liquid to 10.5, so that all the ammonium ions in the waste liquid are converted into ammonia;

[0043] Ammonia Removal by Hypergravity: The ammonia removal unit uses a distillation process to remove ammonia from the waste liquid. The waste liquid is heated by steam at 120 kg / h and 110°C. Under hypergravity conditions, ammonia is separated from the waste liquid by rotation, while simultaneously recovering ammonia water with a mass concentration ≥20%. After being cooled by water at 7°C, the deammoniation waste liquid is fed into a deammoniation product water storage tank. At this point, the main components of the waste liquid are radioactive nuclides and inorganic salts. The unit processing capacity is 1 m³. 3 / h, ammonia removal product water storage tank volume 2m³ 3 ;

[0044] (3) pH adjustment: The waste liquid after ammonia removal is stored in the ammonia removal product water storage tank. The pH value is adjusted to 8.5 as needed before being input into the first-stage reverse osmosis unit (ultra-high pressure reverse osmosis unit).

[0045] First-stage reverse osmosis: Within the first-stage reverse osmosis unit (ultra-high pressure reverse osmosis unit), a spiral-wound polyamide membrane with a pressure rating of 1800 PSI and a desalination rate exceeding 99.7% is used. The waste liquid is circulated and concentrated, increasing the salt content of the concentrated waste liquid (first-stage concentrated phase) to approximately 1 × 10⁻⁶. 5 mg / L, radionuclides and most inorganic salts are retained in this unit and transported to the first-stage reverse osmosis concentrated phase tank. Permeate water (first-stage desalination phase) is transported to the first-stage reverse osmosis desalination phase tank for temporary storage; unit processing capacity is 1m³. 3 / h, first-stage reverse osmosis concentrated phase tank volume 1m³ 3 The volume of the light phase tank is 2m³. 3 ;

[0046] (4) Membrane evaporation crystallization: The high-salt concentrated waste liquid enters the membrane evaporation crystallization unit, where it undergoes rotary evaporation and crystallization under steam heating conditions of 150 kg / h and 110℃. The crystals are scraped off the crystal adhesion surface by a scraper, yielding inorganic salt crystals with a water content of approximately 7%, which are then collected, transported, and temporarily stored. The condensate from the evaporation waste liquid is cooled by low-temperature water condensation at 7℃ and then transported to the reverse osmosis unit for secondary treatment. The unit's processing capacity is 1 m³ / h. 3 / h;

[0047] Secondary reverse osmosis: The waste liquid vapor condensate generated by crystallization and the permeate water (first-stage desalinated phase) from the primary reverse osmosis unit are both sent to the secondary reverse osmosis unit (high-pressure reverse osmosis unit) for treatment. The secondary reverse osmosis unit uses an aromatic polyamide composite membrane with a pressure resistance rating of 1000 PSI and a desalination rate of over 99%. The concentrated phase liquid (secondary concentrated phase) from the secondary reverse osmosis unit is returned to the primary reverse osmosis unit for recycling.

[0048] (5) The permeate (secondary desalinated phase) from the secondary reverse osmosis unit meets discharge requirements and can be discharged. The unit's treatment capacity is 1m³. 3 / h;

[0049] Reverse Osmosis + EDI: The permeate water (secondary desalinated phase) from the secondary reverse osmosis unit can be temporarily stored in the secondary reverse osmosis desalinated phase tank before being fed into the reverse osmosis + EDI unit for further treatment. The reverse osmosis unit uses an aromatic polyamide composite membrane with a pressure rating of 450 PSI and a desalination rate higher than 99%. The EDI unit uses an electrodeionization module with a product water resistivity of 16.0–18.2 MΩ·cm and a recovery rate of 90%–99%, reducing the final product water conductivity to below 0.1 μS / cm (25℃), meeting the requirements for recycled water quality. The concentrated phase water from the reverse osmosis + EDI unit is returned to the secondary reverse osmosis unit for recycling. The unit's processing capacity is 1 m³ / s. 3 / h, Secondary reverse osmosis desalination tank volume 2m³ 3 .

[0050] The above-mentioned treatment methods effectively treated the waste liquid containing organic matter and the waste liquid without organic matter in the production line of the new nuclear fuel element. The treated waste liquid can meet the requirements of the national emission standards. After deep purification treatment by reverse osmosis and electro-deionization, the qualified waste liquid can be reused.

[0051] The discharge indicators for the waste liquid treated by the above methods are: pH = 6-9, suspended solids <70mg / L, total α ≤1Bq / L, total β and γ ≤10Bq / L, ammonia nitrogen ≤3mg / L, total nitrogen ≤15mg / L, and COD ≤40mg / L.

[0052] (Where, total α, total β, and γ refer to the total radioactivity concentration of α rays, and the total radioactivity concentration of β and γ rays in the waste liquid, respectively; ammonia nitrogen refers to combined nitrogen existing in the form of ammonia or ammonium ions, that is, in water as free ammonia (NH3) and ammonium ions (NH4) + Nitrogen exists in various forms; Total Nitrogen (TN): The total nitrogen content in water is one of the important indicators for measuring water quality. It is defined as the total amount of various forms of inorganic and organic nitrogen in water.

[0053] No secondary liquid waste (such as separated ethanol, formaldehyde, etc.) is generated after treatment;

[0054] Ammonia is removed from wastewater containing no organic matter, and then recycled after the concentration reaches 20%.

[0055] The standards for waste liquid reuse after treatment (waste liquid that meets the reuse standard after treatment) are: conductivity ≤ 0.1 μS / cm (25℃), COD ≤ 40 mg / L.

[0056] Example 2

[0057] This embodiment designs and provides a method for treating complex radioactive waste liquid (containing organic waste liquid and non-organic waste liquid) generated by the above-mentioned novel nuclear fuel element production line, including the following steps:

[0058] (1) Waste liquid containing organic matter and waste liquid without organic matter shall be stored in the corresponding organic waste liquid storage tank and inorganic waste liquid storage tank respectively;

[0059] Supercritical water oxidation: Wastewater containing organic matter is fed into the supercritical water oxidation unit, and 20wt% sodium hydroxide solution is added to adjust the pH to 8. Based on the organic matter content in the wastewater, 40wt% sucrose solution is added for pretreatment. Under the combined action of 20MPa pressure, 550℃ temperature, and saturated oxygen, the organic components in the wastewater are oxidized and decomposed, reducing the COD of the produced water to below 80mg / L. The produced water is then output to an inorganic wastewater storage tank to obtain mixed wastewater. The tail gas generated by the system is absorbed by the recycled production water. The unit treatment capacity is 100L / h.

[0060] (2) pH adjustment: Add 20wt% sodium hydroxide solution to adjust the pH of the mixed waste liquid to 11, so that all the ammonium ions in the waste liquid are converted into ammonia;

[0061] Ammonia Removal by Hypergravity: The ammonia removal unit uses a distillation process to remove ammonia from the waste liquid. The waste liquid is heated by steam at 115 kg / h and 105°C. Under hypergravity conditions, ammonia is separated from the waste liquid by rotation, while simultaneously recovering ammonia water with a mass concentration ≥20%. After being cooled by water at 7°C, the deammoniation waste liquid is fed into the deammoniation product water storage tank. At this point, the main components of the waste liquid are radioactive nuclides and inorganic salts. The unit processing capacity is 1 m³. 3 / h;

[0062] (3) pH adjustment: The waste liquid after ammonia removal is stored in the ammonia removal product water storage tank. The pH value is adjusted to 8 as needed and then fed into the first-stage reverse osmosis unit (ultra-high pressure reverse osmosis unit).

[0063] First-stage reverse osmosis: Within the first-stage reverse osmosis unit (ultra-high pressure reverse osmosis unit), a spiral-wound polyamide membrane with a pressure rating of 1800 PSI and a desalination rate exceeding 99.7% is used. The waste liquid is circulated and concentrated, increasing the salt content of the concentrated waste liquid (first-stage concentrated phase) to approximately 1 × 10⁻⁶. 5 mg / L, radionuclides and most inorganic salts are retained in this unit and transported to the first-stage reverse osmosis concentrated phase tank. Permeate water (first-stage desalination phase) is transported to the first-stage reverse osmosis desalination phase tank for temporary storage; unit processing capacity is 1m³. 3 / h;

[0064] (4) Membrane Evaporation Crystallization: The high-salt concentrated waste liquid enters the membrane evaporation crystallization unit, where it undergoes rotary evaporation and crystallization under steam heating conditions of 135 kg / h and 105℃. The crystals are scraped off the crystal adhesion surface by a scraper, yielding inorganic salt crystals with a water content of approximately 7%. These crystals are collected, transported, and temporarily stored. The condensate from the evaporation waste liquid is cooled by low-temperature water condensation at 7℃ and then transported to the reverse osmosis unit for secondary treatment. The unit's processing capacity is 1 m³ / h. 3 / h;

[0065] Secondary reverse osmosis: The waste liquid vapor condensate generated by crystallization and the permeate water (first-stage desalinated phase) from the primary reverse osmosis unit are both sent to the secondary reverse osmosis unit (high-pressure reverse osmosis unit) for treatment. The secondary reverse osmosis unit uses an aromatic polyamide composite membrane with a pressure resistance rating of 1000 PSI and a desalination rate of over 99%. The concentrated phase liquid (secondary concentrated phase) from the secondary reverse osmosis unit is returned to the primary reverse osmosis unit for recycling.

[0066] (5) The permeate (secondary desalinated phase) from the secondary reverse osmosis unit meets discharge requirements and can be discharged. The unit's treatment capacity is 1m³. 3 / h;

[0067] Reverse Osmosis + EDI: The permeate water (secondary desalinated phase) from the secondary reverse osmosis unit can be temporarily stored in the secondary reverse osmosis desalinated phase tank before being fed into the reverse osmosis + EDI unit for further treatment. The reverse osmosis unit uses an aromatic polyamide composite membrane with a pressure rating of 450 PSI and a desalination rate higher than 99%. The EDI unit uses an electrodeionization module with a product water resistivity of 16.0–18.2 MΩ·cm and a recovery rate of 90%–99%, reducing the final product water conductivity to below 0.1 μS / cm (25℃), meeting the requirements for recycled water quality. The concentrated phase water from the reverse osmosis + EDI unit is returned to the secondary reverse osmosis unit for recycling. The unit's processing capacity is 1 m³ / s. 3 / h.

[0068] The above-mentioned treatment methods effectively treated the waste liquid containing organic matter and the waste liquid without organic matter in the production line of the new nuclear fuel element. The treated waste liquid can meet the requirements of the national emission standards. After deep purification treatment by reverse osmosis and electro-deionization, the qualified waste liquid can be reused.

[0069] Example 3

[0070] This embodiment designs and provides a method for treating complex radioactive waste liquid (containing organic waste liquid and non-organic waste liquid) generated by the above-mentioned novel nuclear fuel element production line, including the following steps:

[0071] (1) Waste liquid containing organic matter and waste liquid without organic matter shall be stored in the corresponding organic waste liquid storage tank and inorganic waste liquid storage tank respectively;

[0072] Supercritical water oxidation: Wastewater containing organic matter is fed into the supercritical water oxidation unit, and 40wt% sodium hydroxide solution is added to adjust the pH to 9. Based on the organic matter content in the wastewater, 80wt% sucrose solution is added for pretreatment. Under the combined action of 15MPa pressure, 450℃ temperature, and saturated oxygen, the organic components in the wastewater are oxidized and decomposed, reducing the COD of the produced water to below 80mg / L. The produced water is then discharged to an inorganic wastewater storage tank, resulting in a mixed wastewater. The tail gas generated by the system is absorbed by the recycled production water. The unit processing capacity is 100L / h.

[0073] (2) pH adjustment: Add 40wt% sodium hydroxide solution to adjust the pH of the mixed waste liquid to 11.5, so that all the ammonium ions in the waste liquid are converted into ammonia;

[0074] Ammonia Removal by Hypergravity: The ammonia removal unit uses a distillation process to remove ammonia from the waste liquid. The waste liquid is heated by steam at 110 kg / h and 115°C. Under hypergravity conditions, ammonia is separated from the waste liquid by rotation, while ammonia water with a mass concentration ≥20% is recovered. After being cooled by water at 7°C, the deammoniation waste liquid is fed into the ammonia removal product water storage tank. At this point, the main components of the waste liquid are radioactive nuclides and inorganic salts. The unit processing capacity is 1 m³. 3 / h;

[0075] (3) pH adjustment: The waste liquid after ammonia removal is stored in the ammonia removal product water storage tank. The pH value is adjusted to 9 as needed and then fed into the first-stage reverse osmosis unit (ultra-high pressure reverse osmosis unit).

[0076] First-stage reverse osmosis: Within the first-stage reverse osmosis unit (ultra-high pressure reverse osmosis unit), a spiral-wound polyamide membrane with a pressure rating of 1800 PSI and a desalination rate exceeding 99.7% is used. The waste liquid is circulated and concentrated, increasing the salt content of the concentrated waste liquid (first-stage concentrated phase) to approximately 1 × 10⁻⁶. 5 mg / L, radionuclides and most inorganic salts are retained in this unit and transported to the first-stage reverse osmosis concentrated phase tank. Permeate water (first-stage desalination phase) is transported to the first-stage reverse osmosis desalination phase tank for temporary storage; unit processing capacity is 1m³. 3 / h;

[0077] (4) Membrane Evaporation Crystallization: The high-salt concentrated waste liquid enters the membrane evaporation crystallization unit, where it undergoes rotary evaporation and crystallization under steam heating conditions of 120 kg / h and 115℃. The crystals are scraped off the crystal adhesion surface by a scraper, yielding inorganic salt crystals with a water content of approximately 7%. These crystals are collected, transported, and temporarily stored. The condensate from the evaporation waste liquid is cooled by low-temperature water condensation at 7℃ and then transported to the reverse osmosis unit for secondary treatment. The unit's processing capacity is 1 m³ / h. 3 / h;

[0078] Secondary reverse osmosis: The waste liquid vapor condensate generated by crystallization and the permeate water (first-stage desalinated phase) from the primary reverse osmosis unit are both sent to the secondary reverse osmosis unit (high-pressure reverse osmosis unit) for treatment. The secondary reverse osmosis unit uses an aromatic polyamide composite membrane with a pressure resistance rating of 1000 PSI and a desalination rate of over 99%. The concentrated phase liquid (secondary concentrated phase) from the secondary reverse osmosis unit is returned to the primary reverse osmosis unit for recycling.

[0079] (5) The permeate (secondary desalinated phase) from the secondary reverse osmosis unit meets discharge requirements and can be discharged. The unit's treatment capacity is 1m³. 3 / h;

[0080] Reverse Osmosis + EDI: The permeate water (secondary desalinated phase) from the secondary reverse osmosis unit can be temporarily stored in the secondary reverse osmosis desalinated phase tank before being fed into the reverse osmosis + EDI unit for further treatment. The reverse osmosis unit uses an aromatic polyamide composite membrane with a pressure rating of 450 PSI and a desalination rate higher than 99%. The EDI unit uses an electrodeionization module with a product water resistivity of 16.0–18.2 MΩ·cm and a recovery rate of 90%–99%, reducing the final product water conductivity to below 0.1 μS / cm (25℃), meeting the requirements for recycled water quality. The concentrated phase water from the reverse osmosis + EDI unit is returned to the secondary reverse osmosis unit for recycling. The unit's processing capacity is 1 m³ / s. 3 / h.

[0081] The above-mentioned treatment methods effectively treated the waste liquid containing organic matter and the waste liquid without organic matter in the production line of the new nuclear fuel element. The treated waste liquid can meet the requirements of the national emission standards. After deep purification treatment by reverse osmosis and electro-deionization, the qualified waste liquid can be reused.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, alterations, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for treating complex component radioactive liquid waste, characterized by, Includes the following steps: (1) Add sodium hydroxide solution to the waste liquid containing organic matter and adjust the pH value to 8-9, then add sucrose solution for pretreatment, and carry out oxidative decomposition treatment at a pressure of 15-25 MPa and a temperature of 450-650℃. The treated water is mixed with the waste liquid without organic matter to obtain a mixed waste liquid. (2) Adjust the pH value of the mixed waste liquid to 10.5-11.5, and then heat it with steam at 110-120 kg / h and 105-115℃. Under hypergravity, rotate to separate the ammonia in the waste liquid. When the mass concentration of ammonia water is ≥20%, it is recycled. The deammoniation waste liquid is cooled with water at 7℃. (3) After adjusting the pH value of the deammoniation waste liquid to 8-9, the waste liquid is fed into the first-stage reverse osmosis unit. The waste liquid is circulated and concentrated using a spiral-wound polyamide membrane with a pressure resistance of 1800 PSI and a desalination rate of more than 99.7%. After concentration, a first-stage concentrated phase and a first-stage dilute phase are obtained. (4) The primary concentrated phase is subjected to rotary evaporation and crystallization under steam heating conditions of 120-150 kg / h and 105-115℃ to collect inorganic salt crystals. The waste liquid vapor generated by evaporation is cooled by water condensation at 7℃ and sent to the secondary reverse osmosis unit along with the primary desalted phase. The unit uses an aromatic polyamide composite membrane with a pressure resistance of 1000 PSI and a desalination rate of over 99% for circulation concentration to obtain the secondary concentrated phase and the secondary desalted phase. The secondary concentrated phase is returned to the primary reverse osmosis unit for circulation treatment. (5) Discharge the secondary light phase from step (4) or input it into the reverse osmosis + EDI unit for deep treatment and reuse.

2. The processing method according to claim 1, characterized in that, The reverse osmosis + EDI treatment step in step (5) includes: inputting the secondary desalinated phase into the reverse osmosis + EDI unit. The reverse osmosis unit uses an aromatic polyamide composite membrane with a pressure rating of 450 PSI and a desalination rate of over 99%. The EDI unit uses an electro-deionization module with a product water resistivity of 16.0 to 18.2 MΩ·cm and a recovery rate of 90% to 99%, so that the final product water conductivity is reduced to below 0.1 μS / cm (25℃).

3. The processing method according to claim 2, characterized in that, The concentrated water from the reverse osmosis + EDI unit is returned to the secondary reverse osmosis unit for recycling.

4. The processing method according to claim 1, characterized in that, The complex radioactive waste liquid includes waste liquid containing organic matter and waste liquid without organic matter.

5. The processing method according to claim 1, characterized in that, In step (1), the waste liquid containing organic matter is input into the supercritical water oxidation unit, and 20wt% to 40wt% sodium hydroxide solution is added to adjust the pH value to 8 to 9. According to the organic matter content in the waste liquid, 40wt% to 80wt% sucrose solution is added for pretreatment. Under the combined action of 25MPa pressure, 650℃ temperature and saturated oxygen, the organic components in the waste liquid are oxidized and decomposed, so that the COD of the produced water is reduced to below 80mg / L. The produced water is then mixed with the waste liquid without organic matter.

6. The processing method according to claim 5, characterized in that, Add 30wt% sodium hydroxide solution to adjust the pH to 8, and add 60wt% sucrose solution for pretreatment based on the organic matter content in the waste liquid.

7. The processing method according to claim 1, characterized in that, In step (2), 20wt% to 40wt% sodium hydroxide solution is added to adjust the pH value of the mixed waste liquid to 11, so that all ammonium ions in the waste liquid are converted into ammonia; then, the waste liquid is heated by 120kg / h, 110℃ steam, and the ammonia in the waste liquid is separated by rotation under hypergravity. When the mass concentration of ammonia water is ≥20%, it is recovered, and the deammoniation waste liquid is cooled by 7℃ low temperature water.

8. The processing method according to claim 1, characterized in that, In step (3), the pH value of the deammoniation waste liquid is adjusted to 8 and then fed into the first-stage reverse osmosis unit. The waste liquid is circulated and concentrated using a spiral-wound polyamide membrane with a pressure resistance of 1800 PSI and a desalination rate of 99.7%. The resulting first-stage concentrated phase and first-stage dilute phase are stored separately.

9. The processing method according to claim 1, characterized in that, In step (4), the primary concentrated phase is subjected to rotary evaporation and crystallization under steam heating conditions of 150 kg / h and 110°C. The collected inorganic salt crystals with a water content of 5% to 8% are transported and temporarily stored. The waste liquid vapor generated by evaporation is cooled by water condensation at 7°C and sent to the secondary reverse osmosis unit along with the primary desalinated phase. The unit uses an aromatic polyamide composite membrane with a pressure resistance of 1000 PSI and a desalination rate of 99% for circulation concentration to obtain the secondary concentrated phase and the secondary desalinated phase. The secondary concentrated phase is returned to the primary reverse osmosis unit for circulation treatment.

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