Method for purifying radioactive laundry wastewater

Abstract

The present invention discloses a radioactive laundry wastewater purification method, and relates to the field of radioactive wastewater treatment, the purification method comprises the following steps: step a, wastewater is introduced into a first circulation loop system, and impurities with particle sizes of 0.03 [mu] m or more in the wastewater are filtered; step b, introducing the produced water treated and obtained by the first circulation loop system in the step a into a second circulation loop system, decomposing a surfactant in the produced water and intercepting suspended solids; c, the produced water obtained through treatment of the second circulation loop system in the step b is introduced into a third circulation loop system, and 90% or above of uranium ions in the produced water are filtered out. The method has the beneficial effects that impurities such as hair, fabric fibers, a surfactant and suspended solids in the radioactive laundry wastewater are sequentially removed, the uranium ion concentration is greatly reduced, waste minimization is realized, and the technical effects of continuous production and the like can be met.

Description

Technical Field

[0001] The invention relates to the field of radioactive wastewater treatment, and in particular to a method for purifying radioactive laundry wastewater. Background Art

[0002] Radioactive laundry wastewater is wastewater generated during the washing and decontamination process of work clothes, hats, gloves and other fabrics worn by workers who handle radioactive materials. In addition to hair, fabric fibers, surfactants and other substances, it also contains radioactive nuclide ions, such as uranium ions of a certain concentration, which cannot be directly discharged into the production sewage system and needs to be purified to remove the radioactivity.

[0003] Since the content of radioactive nuclides in this part of wastewater is low and the recovery is not economical, cheap and readily available lime is generally used for precipitation treatment, that is, the radioactive nuclide ions in the wastewater react with the calcium ions in the lime to form a precipitate that is filtered out; for example, when the wastewater contains fluoride ions, the fluoride ions react with lime to form a calcium fluoride precipitate, and the radioactive nuclide ions are adsorbed on the precipitate, and the resulting precipitate is temporarily stored as radioactive solid waste; however, the compliance rate of wastewater after one-time treatment by lime precipitation is low, and the wastewater needs to be returned for repeated treatment, thereby generating more radioactive solid waste, and waste minimization cannot be achieved. Moreover, the salt content and turbidity of the treated wastewater are very high and cannot be reused.

[0004] If conventional membrane filtration technology is used directly for treatment, the membrane components are prone to clogging, which requires flushing with a large amount of water to clear the blockage. However, this will produce more wastewater and cannot meet the requirements of continuous production.

[0005] Therefore, it is necessary to design a method for purifying radioactive laundry wastewater to minimize waste and meet the requirements of continuous production. Summary of the invention

[0006] In order to overcome the low compliance rate of the existing lime precipitation method for treating radioactive wastewater and the inability to minimize waste, conventional membrane filtration technology is used for treatment, which is prone to the problem of membrane component clogging.

[0007] The present invention provides a method for purifying radioactive laundry wastewater, the method comprising the following steps: Step a, passing the radioactive laundry wastewater into a first circulation loop system, filtering impurities with a particle size of 0.03 μm or more in the radioactive laundry wastewater; Step b, passing the produced water obtained by the first circulation loop system in step a into the second circulation loop system to decompose the surfactant in the produced water and intercept the suspended matter in the produced water; Step c, passing the produced water obtained by the second circulation loop system in step b into the third circulation loop system, filtering more than 90% of the uranium ions in the produced water; Step d: using an analysis and detection device to detect the produced water obtained by the third circulation loop system in step c, and detecting whether the uranium ion concentration in the produced water meets the emission standards.

[0008] Preferably, in step a, the first circulation loop system comprises a hair fiber filter, a membrane pool, an immersion ultrafiltration device and a filter press device; Wherein, the water inlet of the hair fiber filter and the discharge port of the radioactive laundry wastewater collection pool are connected through a pipeline, the water outlet of the hair fiber filter and the water inlet of the membrane pool are connected through a pipeline, the submerged ultrafiltration device is arranged in the membrane pool, the water outlet of the submerged ultrafiltration device and the second circulation loop system are connected through a pipeline, the water outlet of the membrane pool and the water inlet of the filter press are connected through a pump, and the water outlet of the filter press and the water inlet of the hair fiber filter are connected through a pipeline; The first circulation loop system processes the wastewater comprising the following steps: Step a1, passing the radioactive laundry wastewater into the hair fiber filter, filtering the first impurities with a particle size of more than 0.5 mm in the radioactive laundry wastewater to obtain first produced water, landfilling the first impurities, and the first produced water enters step a2; Step a2, passing the first produced water into the membrane pool, sucking the first produced water in the membrane pool by a pump, and allowing the first produced water to pass through the membrane surface of the submerged ultrafiltration device, intercepting second impurities with a particle size of more than 0.03 μm in the first produced water and obtaining second produced water, intercepting the second impurities and retaining them in the membrane pool, and the second produced water enters step b; Step a3, the second impurities in the membrane pool are sucked into the filter press device by the pump, and filter residue and filtrate are obtained by filter pressing. The filter residue is landfilled, and the filtrate is returned to step a1 and passed into the hair fiber filter to perform a closed-loop cycle treatment.

[0009] Preferably, in the step a1, the filtering accuracy of the hair fiber filter is 0.5 mm; and the first impurities are filtered by a detachable filter basket in the hair fiber filter, and the first impurities in the detachable filter basket are regularly cleaned and landfilled.

[0010] Preferably, in the step a2, the submerged ultrafiltration device uses an open membrane element, the filtration accuracy of the submerged ultrafiltration device is ≤0.03 μm, and the turbidity of the produced water of the submerged ultrafiltration device is ≤50 NTU.

[0011] Preferably, in step b, the second circulation loop system comprises an electrocatalytic oxidation device and an ultrafiltration device, and the ultrafiltration device comprises a produced water outlet and a concentrated water outlet; wherein the water inlet of the electrocatalytic oxidation device and the water outlet of the submerged ultrafiltration device are connected via a pipeline, the water outlet of the electrocatalytic oxidation device and the water inlet of the ultrafiltration device are connected via a pipeline, the produced water outlet of the ultrafiltration device and the third circulation loop system are connected via a pipeline, and the concentrated water outlet of the ultrafiltration device and the water inlet of the electrocatalytic oxidation device are connected via a pipeline; The second circulation loop system processes the second produced water comprising the following steps: Step b1, passing the second produced water into the electrocatalytic oxidation device, electrocatalytically oxidizing and decomposing the surfactant in the second produced water to obtain third produced water, and the third produced water enters step b2; Step b2, passing the third produced water into the ultrafiltration device, intercepting suspended matter with a particle size of more than 1 nm in the third produced water, and obtaining fourth produced water and first concentrated water containing the intercepted suspended matter; wherein the fourth produced water enters step c, and the first concentrated water returns to step b1 and passes into the electrocatalytic oxidation device for a closed-loop cycle treatment.

[0012] Preferably, in step b1, the COD value of the electrocatalytic oxidation water is less than 100 mg / L. Preferably, in step b2, the filtration accuracy of the ultrafiltration device is 1-10 nm, and the water production rate of the ultrafiltration device is ≥90%.

[0013] Preferably, in step c, the third circulation loop system comprises a nanofiltration device, a reverse osmosis device and a radionuclide recovery system, the nanofiltration device comprises a concentrated water outlet, and the reverse osmosis device comprises a produced water outlet and a concentrated water outlet; wherein the water inlet of the nanofiltration device and the produced water outlet of the ultrafiltration device are connected via a pipeline, the concentrated water outlet of the nanofiltration device and the radionuclide recovery system are connected via a pipeline, the produced water outlet of the nanofiltration device and the water inlet of the reverse osmosis device are connected via a pipeline, and the concentrated water outlet of the reverse osmosis device and the water inlet of the nanofiltration device are connected via a pipeline; The third circulation loop system processes the third produced water and comprises the following steps: Step c1, passing the fourth produced water into the nanofiltration device, intercepting more than 70% of the uranium ions in the fourth produced water, and obtaining the fifth produced water and the second concentrated water containing the intercepted uranium ions, the fifth produced water enters step c2, and the second concentrated water is passed into the radionuclide recovery system; Step c2, passing the fifth produced water into the reverse osmosis device, intercepting more than 80% of the uranium ions in the fifth produced water, and obtaining the sixth produced water and the third concentrated water containing the intercepted uranium ions, sampling the sixth produced water and entering step d, and the third concentrated water returns to step c1 and passes into the nanofiltration device for a closed-loop treatment.

[0014] Preferably, in step c1, the filtration accuracy of the nanofiltration device is 1-2 nm, the interception rate of the nanofiltration device is ≥70%, and the water production rate of the nanofiltration device is ≥85%; The filtration accuracy of the reverse osmosis device is 0.1 nm, the interception rate of the reverse osmosis device is ≥80%, and the water production rate of the reverse osmosis device is ≥85%.

[0015] Preferably, in step d, the reverse osmosis device further comprises a water production outlet, the water production outlet of the reverse osmosis device can be sampled, the water production outlet of the reverse osmosis device is connected to the outside or the water use system through a pipeline, and the water production outlet of the reverse osmosis device is also connected to the water inlet of the reverse osmosis device through a pipeline; the analysis and detection device is a trace uranium analyzer; If the uranium concentration of the sampled sixth produced water is less than 50 μg / L, the test result is qualified and can be discharged to the outside or discharged to the water system for recycling; if the uranium concentration of the sampled sixth produced water is ≥50 μg / L, the test result is unqualified, and the sixth produced water is returned to the step c2 and passed into the reverse osmosis device for a closed-loop cycle treatment.

[0016] Beneficial effects: The beneficial effects produced by the technical solution of the present invention are as follows: (1) In step a, the radioactive laundry wastewater is introduced into the first circulation loop system, and impurities with a particle size of 0.03 μm or more in the radioactive laundry wastewater are filtered out, that is, hair, textile fibers, large particles of impurities, etc. in the radioactive laundry wastewater can be filtered out to avoid clogging the second circulation loop system and the third circulation loop system.

[0017] (2) In step b, the produced water obtained by the first circulation loop system in step a is introduced into the second circulation loop system to decompose the surfactant in the produced water and intercept the suspended matter in the produced water to avoid clogging the third circulation loop system.

[0018] (3) In step c, the produced water obtained by the second circulation loop system in step b is introduced into the third circulation loop system to filter out more than 90% of the uranium ions in the produced water, thereby reducing the concentration of radioactive nuclide ions in the radioactive laundry wastewater to meet the discharge requirements.

[0019] (4) In step d, the produced water obtained by the third circulation loop system in step c is detected by using an analytical detection device to detect whether the uranium ion concentration in the produced water meets the emission standards, and the produced water is discharged only after it is confirmed to meet the emission standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 The present invention is a flow chart of a method for purifying radioactive laundry wastewater.

[0022] Figure 2 The figure is a detailed flow chart of a method for purifying radioactive laundry wastewater in the present invention.

[0023] Figure 3 For the present invention Figure 2 Enlarged view of the first circulation loop.

[0024] Figure 4 For the present invention Figure 2 A magnified view of the second circulation loop.

[0025] Figure 5 For the present invention Figure 2 A magnified view of the third circulation loop. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Embodiment 1

[0028] Please refer to Figures 1 to 5 The embodiment of the present invention provides a method for purifying radioactive laundry wastewater, the purification method comprising the following steps: Step a, passing radioactive laundry wastewater with a uranium content of less than 10 mg / L, a COD value of about 800 mg / L, and a turbidity of about 300 NTU into the first circulation loop system, filtering impurities with a particle size of more than 0.03 μm in the wastewater, that is, filtering hair, fabric fibers, large particle impurities, etc. in the radioactive laundry wastewater to avoid clogging the second circulation loop system and the third circulation loop system; Step b, passing the produced water obtained by the first circulation loop system in step a into the second circulation loop system, decomposing the surfactant and other organic matter in the produced water, and further intercepting the colloid and other and other suspended matter to avoid clogging the third circulation loop system; Step c, passing the produced water obtained by the second circulation loop system in step b into the third circulation loop system, filtering more than 90% of the uranium ions in the produced water, and reducing the concentration of radioactive nuclide ions in the radioactive laundry wastewater to meet the discharge requirements; Step d: using an analysis and detection device to detect the produced water obtained by the third circulation loop system in step c, and detecting whether the uranium ion concentration in the produced water meets the emission standards, and then discharging it after confirming that it meets the standards.

[0029] In step a, the first circulation loop system includes a hair fiber filter, a membrane pool, an immersion ultrafiltration device and a filter press device; wherein the water inlet of the hair fiber filter and the discharge port of the radioactive laundry wastewater collection pool are connected through a pipeline, the water outlet of the hair fiber filter and the water inlet of the membrane pool are connected through a pipeline, the immersion ultrafiltration device is arranged in the membrane pool, the water outlet of the immersion ultrafiltration device and the second circulation loop system are connected through a pipeline, the water outlet of the membrane pool and the water inlet of the filter press device are connected through a pump, and the water outlet of the filter press device and the water inlet of the hair fiber filter are connected through a pipeline; The first circulation loop system for treating wastewater includes the following steps: Step a1, passing the radioactive laundry wastewater into a hair fiber filter, the filtration accuracy of the hair fiber filter is 0.5mm, and filtering the first impurities with a particle size of 0.5mm or more in the radioactive laundry wastewater through a detachable filter basket in the hair fiber filter to obtain the first produced water, that is, filtering the hair and large particle impurities with a particle size of 0.5mm or more. When the interception amount of solid impurities in the detachable filter basket increases, the filtration channel will be blocked, resulting in an increase in the filtration pressure difference and a decrease in the wastewater flow rate. When the filtration pressure difference is higher than a certain value or the wastewater flow rate is lower than a certain value, it is necessary to regularly clean the first impurities in the detachable filter basket and landfill them for treatment, and the first produced water enters step a2; Step a2, passing the first produced water into the membrane pool, pumping the first produced water in the membrane pool by a pump, and allowing the first produced water to pass through the membrane surface of the submerged ultrafiltration device, the submerged ultrafiltration device adopts an open membrane element, the filtration accuracy of the submerged ultrafiltration device is ≤0.03μm, the submerged ultrafiltration device intercepts the second impurities with a particle size of 0.03μm or more in the first produced water and obtains the second produced water, the turbidity of the produced water of the submerged ultrafiltration device is ≤50NTU, so that the second produced water meets the water inlet requirements of the electrocatalytic oxidation device, that is, the fine hair, textile fibers and other impurities with a particle size between 0.03μm and 0.5mm in the first produced water are filtered, the second impurities are intercepted and retained in the membrane pool, and the second produced water enters step b; Step a3, the second impurity is precipitated at the bottom of the membrane pool, and the second impurity at the bottom of the membrane pool is sucked to the filter press device by a pump, and the filter residue and filtrate are obtained by filter pressing. The filter residue is landfilled, and the filtrate is returned to step a1, and the filtrate is passed into the hair fiber filter to perform a closed-loop cycle treatment to minimize the waste generated.

[0030] In step b, the second circulation loop system includes an electrocatalytic oxidation device and an ultrafiltration device, and the ultrafiltration device includes a concentrated water outlet; wherein the water inlet of the electrocatalytic oxidation device and the water outlet of the submerged ultrafiltration device are connected through a pipeline, the water outlet of the electrocatalytic oxidation device and the water inlet of the ultrafiltration device are connected through a pipeline, and the concentrated water outlet of the ultrafiltration device and the water inlet of the electrocatalytic oxidation device are connected through a pipeline; The second circulation loop system for treating the second produced water includes the following steps: Step b1, passing the second produced water into the electrocatalytic oxidation device, using the hydroxyl radicals (·OH) generated by the electrolysis of water as an oxidant, the hydroxyl radicals oxidize organic matter under electrocatalytic conditions, and decompose the organic matter in the second produced water into water and inorganic matter such as carbon dioxide, that is, the hydroxyl radicals oxidize and decompose the surfactant in the second produced water and organic impurities such as excrement on the surface of human skin, the decomposition rate of organic matter is greater than 90%, and the third produced water is obtained, the third produced water enters step b2, the COD value of the electrocatalytic oxidation produced water is less than 100 mg / L, so that the third produced water meets the water inlet requirement of the ultrafiltration device; Step b2, passing the third produced water into an ultrafiltration device with a filtration accuracy of 1-10 nm and a water production rate of ≥90%, intercepting suspended matter with a particle size of 1 nm or more in the third produced water, and obtaining the fourth produced water and the first concentrated water containing the suspended matter, so as to prevent colloids and other suspended matter from adhering to the membrane components of the subsequent nanofiltration device and the reverse osmosis device; wherein the fourth produced water enters step c, the first concentrated water returns to step b1, and the first concentrated water is passed into the electrocatalytic oxidation device for a closed-loop cycle treatment.

[0031] In step c, the third circulation loop system includes a nanofiltration device, a reverse osmosis device and a radioactive nuclide recovery system, the nanofiltration device includes a produced water outlet and a concentrated water outlet, and the reverse osmosis device includes a produced water outlet and a concentrated water outlet; wherein the water inlet of the nanofiltration device is connected to the produced water outlet of the ultrafiltration device through a pipeline, the concentrated water outlet of the nanofiltration device is connected to the radioactive nuclide recovery system through a pipeline, the produced water outlet of the nanofiltration device is connected to the water inlet of the reverse osmosis device through a pipeline, the produced water outlet of the reverse osmosis device can be sampled and is connected to the water inlet of the reverse osmosis device through a pipeline, and the concentrated water outlet of the reverse osmosis device is connected to the water inlet of the nanofiltration device through a pipeline; The third circulation loop system for treating the third produced water includes the following steps: Step c1, passing the fourth produced water into a nanofiltration device, the filtration accuracy of the nanofiltration device is 1-2nm, the interception rate of the nanofiltration device is ≥70%, the water production rate of the nanofiltration device is ≥85%, more than 70% of the uranium ions in the fourth produced water are intercepted, and the fifth produced water and the second concentrated water containing the intercepted uranium ions are obtained, the fifth produced water enters step c2, and the second concentrated water is passed into the radionuclide recovery system; Step c2, passing the fifth produced water into a reverse osmosis device, the filtration accuracy of the reverse osmosis device is 0.1nm, the interception rate of the reverse osmosis device is ≥80%, the water production rate of the reverse osmosis device is ≥85%, and more than 80% of the uranium ions in the fifth produced water are deeply intercepted again, and the sixth produced water and the third concentrated water containing the intercepted uranium ions are obtained, the sixth produced water is sampled and enters step d, and the third concentrated water is returned to step c1 and passed into the nanofiltration device for a closed-loop cycle treatment; after filtration by the nanofiltration device in step c1 and filtration by the reverse osmosis device in step c2, the overall interception rate of uranium ions is ≥90%.

[0032] In step d, the reverse osmosis device also includes a water production outlet, the water production outlet of the reverse osmosis device can be sampled, the water production outlet of the reverse osmosis device is connected to the outside or the water use system through a pipeline, the water production outlet of the reverse osmosis device is also connected to the water inlet of the reverse osmosis device through a pipeline, and the analysis and detection device is a trace uranium analyzer; the uranium concentration of the sixth produced water sampled by the trace uranium analyzer is 0.01 mg / L, which is less than 50 μg / L, and the test result is qualified, and can be discharged to the outside or discharged to the water use system for recycling.

[0033] Embodiment 2

[0034] The difference between Example 2 and Example 1 is that in step d, if the uranium concentration of the sixth produced water sampled by the trace uranium analyzer is ≥50 μg / L, the test result is unqualified, and the sixth produced water is returned to step c2, and the sixth produced water is passed into the reverse osmosis device for a closed-loop circulation treatment to ensure that the sixth produced water meets the emission standards after further treatment.

[0035] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for purifying radioactive laundry wastewater, characterized in that: The purification method comprises the following steps: Step a, passing the radioactive laundry wastewater into a first circulation loop system, filtering impurities with a particle size of 0.03 μm or more in the radioactive laundry wastewater; Step b, passing the produced water obtained by the first circulation loop system in step a into the second circulation loop system to decompose the surfactant in the produced water and intercept the suspended matter in the produced water; Step c, passing the produced water obtained by the second circulation loop system in step b into the third circulation loop system, filtering more than 90% of the uranium ions in the produced water; Step d: using an analysis and detection device to detect the produced water obtained by the third circulation loop system in step c, and detecting whether the uranium ion concentration in the produced water meets the emission standards.

2. A method for purifying radioactive laundry wastewater as claimed in claim 1, characterized in that: In step a, the first circulation loop system comprises a hair fiber filter, a membrane pool, an immersion ultrafiltration device and a filter press device; wherein the water inlet of the hair fiber filter and the discharge port of the radioactive laundry wastewater collection pool are connected via a pipeline, the water outlet of the hair fiber filter and the water inlet of the membrane pool are connected via a pipeline, the immersion ultrafiltration device is arranged in the membrane pool, the water outlet of the immersion ultrafiltration device and the second circulation loop system are connected via a pipeline, the water outlet of the membrane pool and the water inlet of the filter press device are connected via a pump, and the water outlet of the filter press device and the water inlet of the hair fiber filter are connected via a pipeline; The first circulation loop system processes the wastewater comprising the following steps: Step a1, passing the radioactive laundry wastewater into the hair fiber filter, filtering the first impurities with a particle size of more than 0.5 mm in the radioactive laundry wastewater to obtain first produced water, landfilling the first impurities, and the first produced water enters step a2; Step a2, passing the first produced water into the membrane pool, sucking the first produced water in the membrane pool by a pump, and allowing the first produced water to pass through the membrane surface of the submerged ultrafiltration device, intercepting second impurities with a particle size of more than 0.03 μm in the first produced water and obtaining second produced water, intercepting the second impurities and retaining them in the membrane pool, and the second produced water enters step b; Step a3, the second impurities in the membrane pool are sucked into the filter press device by the pump, and filter residue and filtrate are obtained by filter pressing. The filter residue is landfilled, and the filtrate is returned to step a1 and passed into the hair fiber filter to perform a closed-loop cycle treatment.

3. A method for purifying radioactive laundry wastewater as claimed in claim 2, characterized in that: In the step a1, the filtering accuracy of the hair fiber filter is 0.5 mm; and the first impurities are filtered by a detachable filter basket in the hair fiber filter, and the first impurities in the detachable filter basket are regularly cleaned and landfilled.

4. A method for purifying radioactive laundry wastewater as claimed in claim 2, characterized in that: In the step a2, the submerged ultrafiltration device uses an open membrane element, the filtration accuracy of the submerged ultrafiltration device is ≤0.03 μm, and the turbidity of the produced water of the submerged ultrafiltration device is ≤50 NTU.

5. A method for purifying radioactive laundry wastewater as claimed in claim 2, characterized in that: In the step b, the second circulation loop system includes an electrocatalytic oxidation device and an ultrafiltration device, and the ultrafiltration device includes a produced water outlet and a concentrated water outlet; wherein the water inlet of the electrocatalytic oxidation device and the water outlet of the submerged ultrafiltration device are connected via a pipeline, the water outlet of the electrocatalytic oxidation device and the water inlet of the ultrafiltration device are connected via a pipeline, the produced water outlet of the ultrafiltration device and the third circulation loop system are connected via a pipeline, and the concentrated water outlet of the ultrafiltration device and the water inlet of the electrocatalytic oxidation device are connected via a pipeline; The second circulation loop system processes the second produced water comprising the following steps: Step b1, passing the second produced water into the electrocatalytic oxidation device, electrocatalytically oxidizing and decomposing the surfactant in the second produced water to obtain third produced water, and the third produced water enters step b2; Step b2, passing the third produced water into the ultrafiltration device, intercepting suspended matter with a particle size of more than 1 nm in the third produced water, and obtaining fourth produced water and first concentrated water containing the intercepted suspended matter; wherein the fourth produced water enters step c, and the first concentrated water returns to step b1 and passes into the electrocatalytic oxidation device for a closed-loop cycle treatment.

6. A method for purifying radioactive laundry wastewater as claimed in claim 5, characterized in that: In the step b1, the COD value of the water produced by the electrocatalytic oxidation is less than 100 mg / L.

7. A method for purifying radioactive laundry wastewater as claimed in claim 5, characterized in that: In the step b2, the filtration accuracy of the ultrafiltration device is 1-10 nm, and the water production rate of the ultrafiltration device is ≥90%.

8. A method for purifying radioactive laundry wastewater as claimed in claim 5, characterized in that: In the step c, the third circulation loop system includes a nanofiltration device, a reverse osmosis device and a radionuclide recovery system, the nanofiltration device includes a concentrated water outlet, and the reverse osmosis device includes a produced water outlet and a concentrated water outlet; wherein the water inlet of the nanofiltration device and the produced water outlet of the ultrafiltration device are connected through a pipeline, the concentrated water outlet of the nanofiltration device and the radionuclide recovery system are connected through a pipeline, the produced water outlet of the nanofiltration device and the water inlet of the reverse osmosis device are connected through a pipeline, and the concentrated water outlet of the reverse osmosis device and the water inlet of the nanofiltration device are connected through a pipeline; The third circulation loop system for processing the third produced water comprises the following steps: Step c1, passing the fourth produced water into the nanofiltration device, intercepting more than 70% of the uranium ions in the fourth produced water, and obtaining the fifth produced water and the second concentrated water containing the intercepted uranium ions, the fifth produced water enters step c2, and the second concentrated water is passed into the radionuclide recovery system; Step c2, passing the fifth produced water into the reverse osmosis device, intercepting more than 80% of the uranium ions in the fifth produced water, and obtaining the sixth produced water and the third concentrated water containing the intercepted uranium ions, sampling the sixth produced water and entering step d, and the third concentrated water returns to step c1 and passes into the nanofiltration device for a closed-loop treatment.

9. A method for purifying radioactive laundry wastewater as claimed in claim 8, characterized in that: In the step c1, the filtration accuracy of the nanofiltration device is 1-2 nm, the interception rate of the nanofiltration device is ≥70%, and the water production rate of the nanofiltration device is ≥85%; The filtration accuracy of the reverse osmosis device is 0.1 nm, the interception rate of the reverse osmosis device is ≥80%, and the water production rate of the reverse osmosis device is ≥85%.

10. A method for purifying radioactive laundry wastewater as claimed in claim 8, characterized in that: The reverse osmosis device also includes a water production outlet, where samples can be taken, the water production outlet of the reverse osmosis device is connected to the outside or a water use system through a pipeline, and the water production outlet of the reverse osmosis device is also connected to the water inlet of the reverse osmosis device through a pipeline; In the step d, the analysis and detection device is a trace uranium analyzer; If the uranium concentration of the sampled sixth produced water is less than 50 μg / L, the test result is qualified and can be discharged to the outside or discharged to the water system for recycling; if the uranium concentration of the sampled sixth produced water is ≥50 μg / L, the test result is unqualified, and the sixth produced water is returned to the step c2 and passed into the reverse osmosis device for a closed-loop cycle treatment.

Images