阅读说明：本技术 放射性废液处理系统及方法 (Radioactive waste liquid treatment system and method ) 是由 赵璇 王韧骋 李福志 于 2020-06-10 设计创作，主要内容包括：本发明公开了一种放射性废液处理系统及方法。放射性废液处理系统,包括：超滤单元,其包括超滤膜,所述超滤单元用于除去放射性废液中的胶体态核素；浓缩单元,其包括反渗透装置,且所述反渗透装置的进水口与所述超滤单元的净化液出口连接,所述反渗透装置接收所述超滤单元的净化液,以对所述超滤单元的净化液进行反渗透浓缩；离子交换单元,其包括离子交换床,且所述离子交换单元的进水口与所述反渗透装置的浓缩液出口连接,所述离子交换单元接收所述浓缩单元的浓缩液,以将所述浓缩单元的浓缩液富集的放射性核素提取至固相。(The invention discloses a radioactive waste liquid treatment system and a method. A radioactive liquid waste treatment system comprising: the ultrafiltration unit comprises an ultrafiltration membrane and is used for removing colloidal nuclides in radioactive waste liquid; the concentration unit comprises a reverse osmosis device, a water inlet of the reverse osmosis device is connected with a purified liquid outlet of the ultrafiltration unit, and the reverse osmosis device receives the purified liquid of the ultrafiltration unit so as to perform reverse osmosis concentration on the purified liquid of the ultrafiltration unit; an ion exchange unit comprising an ion exchange bed, and a water inlet of the ion exchange unit is connected with a concentrate outlet of the reverse osmosis device, the ion exchange unit receiving the concentrate of the concentration unit to extract radionuclides enriched in the concentrate of the concentration unit to a solid phase.)

1. A radioactive liquid waste treatment system comprising:

the ultrafiltration unit comprises an ultrafiltration membrane and is used for removing colloidal nuclides in radioactive waste liquid;

the concentration unit comprises a reverse osmosis device, a water inlet of the reverse osmosis device is connected with a purified liquid outlet of the ultrafiltration unit, and the reverse osmosis device receives the purified liquid of the ultrafiltration unit so as to perform reverse osmosis concentration on the purified liquid of the ultrafiltration unit;

an ion exchange unit comprising an ion exchange bed, and a water inlet of the ion exchange unit is connected with a concentrate outlet of the reverse osmosis device, the ion exchange unit receiving the concentrate of the concentration unit to extract radionuclides enriched in the concentrate of the concentration unit to a solid phase.

2. The system of claim 1, wherein the ultrafiltration membrane comprises a polymer-based membrane and a polymer membrane layer disposed on the polymer-based membrane, the polymer membrane layer being grafted with a hydrophilic modifier.

3. The system of claim 2, wherein the hydrophilic modifier is selected from the group consisting of hydrophilic group-containing olefinic modifiers, the hydrophilic group comprising one or more of a carboxyl group, a sulfonic acid group, a hydroxyl group, an amide group, and an amino group;

preferably, the hydrophilic modifier comprises acrylic acid.

4. The system of claim 2 or 3, wherein the polymer membrane layer is grafted with the hydrophilic modifier by co-irradiating the membrane material of the polymer membrane layer, the porogen and the hydrophilic modifier.

5. The system according to any one of claims 1 to 3, wherein the ultrafiltration membrane further satisfies one or more of the following (1) to (3):

(1) the water contact angle of the ultrafiltration membrane is less than or equal to 70 degrees;

(2) the Zeta potential of the surface of the ultrafiltration membrane under the condition that the pH value is 7 is more than or equal to-12.5 mV;

(3) the pure water membrane flux of the ultrafiltration membrane under the transmembrane pressure difference of 0.1MPa is 50 L.m^-2·h^-1～600L·m^-2·h^-1。

6. The system of claim 1, wherein the water outlet of the ion exchange unit is connected to the water inlet of the reverse osmosis apparatus such that liquid passing through the ion exchange unit is returned to the reverse osmosis apparatus.

7. The system of claim 1, further comprising a deep purification unit having a water inlet connected to the concentrate unit's purified liquid outlet, the deep purification unit receiving the concentrate unit's purified liquid to remove radionuclides in the concentrate unit's purified liquid.

8. The system of claim 7, wherein the water outlet of the ion exchange unit is connected with the purified liquid outlet of the deep purification unit, so that the liquid passing through the ion exchange unit is merged with the purified liquid of the deep purification unit and then discharged.

9. The system of claim 8, wherein the water outlet of the ion exchange unit is further connected with the water inlet of the reverse osmosis device, so that a part of the liquid passing through the ion exchange unit returns to the reverse osmosis device, and the other part of the liquid is merged with the purified liquid of the deep purification unit and then discharged.

10. The system of claim 7, wherein the deep scrubbing unit comprises:

a water inlet of the reverse osmosis subunit is connected with a purified liquid outlet of the reverse osmosis device, and a concentrated liquid outlet of the reverse osmosis subunit is connected with a water inlet of the reverse osmosis device;

and the water inlet of the continuous electric desalting subunit is connected with the purified liquid outlet of the reverse osmosis subunit, and the concentrated liquid outlet of the continuous electric desalting subunit is connected with the water inlet of the reverse osmosis device.

11. The system of claim 1, further comprising a cesium adsorption device disposed upstream of the ion exchange bed or at an outer water discharge end of the system.

12. A radioactive waste liquid treatment method comprises the following steps:

a) removing colloidal nuclides in the radioactive waste liquid by using an ultrafiltration membrane;

b) performing reverse osmosis concentration on the radioactive waste liquid from which the radioactive nuclide is removed;

c) and extracting the radionuclides enriched by the concentrated solution of the concentration unit to a solid phase by using an ion exchanger.

13. The method of claim 12, further comprising:

returning the purified liquid discharged from the step c) to the step b); and/or the presence of a gas in the gas,

the purified liquid discharged in the step c) is merged with the purified liquid discharged in the step b) and subjected to deep purification, and then discharged.

14. The method of claim 12, wherein the concentration factor of the reverse osmosis concentration in step b) is 2-10 times, preferably 3-5 times.

Technical Field

The invention belongs to the technical field of wastewater treatment, and particularly relates to a radioactive waste liquid treatment system and method.

Background

The nuclear energy has the advantages of cleanness, high efficiency, safety, stability, good economy and the like, and is clean energy with good development prospect. Radioactive waste is inevitably generated during the operation of nuclear power plants, wherein radioactive liquid waste (i.e. radioactive waste liquid) accounts for a large proportion. For nuclear power development and environmental protection, proper treatment of radioactive waste liquid becomes an important content of radioactive waste management.

The radioactive waste liquid generated by the nuclear power plant comprises¹³⁷Cs、⁸⁹Sr、⁹⁰Sr、⁵⁸Co、^110mAg、³H, and the like, and the concentration of the radioactive nuclide in the radioactive waste liquid is extremely low, generally in ng.L^-1The order is even lower and the radionuclides (such as Cs, Sr, Co, etc.) mostly exist in the form of ions, but also some radionuclides (such as Ag and Co) exist in the form of colloids, which undoubtedly increases the difficulty of handling radioactive waste liquids.

The ion exchange process has a good effect of removing the ionic radionuclide, but has almost no effect of removing the colloidal nuclide, and even the colloidal nuclide entering the ion exchange bed can reduce the treatment efficiency of the ion exchange resin and shorten the service life. Therefore, the radioactive waste liquid is currently treated by a chemical flocculation and activated carbon filtration and ion exchange process, wherein a chemical flocculation and activated carbon filtration unit is used for removing the colloidal radionuclide and an ion exchange unit is used for removing the ionic radionuclide by zeolite and ion exchange resin. However, the process still has the following problems:

1) the chemical flocculation unit adopts Fe as flocculant³⁺、Al³⁺Inorganic ions are mainly used, and in order to ensure high removal rate of colloid, a flocculating agent is often excessively added, so that non-radioactive inorganic ions with higher concentration are introduced into the waste liquid. After the waste liquid enters the ion exchange bed, the non-radioactive inorganic ions and the radioactive nuclide ions compete for exchange sites, so that the resin is saturated in advance, and the service life is shortened. Therefore, the amount of radioactive waste generated is large.

2) After adsorbing colloidal nuclides, the activated carbon is treated as radioactive waste, so that the waste amount is further increased.

3) In the process, the working exchange capacity of the ion exchange resin is low, and the utilization rate of the resin is poor, so that the yield of the radioactive waste resin is high.

The current radioactive waste liquid treatment process cannot meet the basic principle of minimizing the radioactive waste, so that the technical scheme for treating the radioactive waste liquid capable of reducing the generation amount of the radioactive waste still needs to be further developed.

Disclosure of Invention

The present invention provides in a first aspect a radioactive liquid waste treatment system comprising:

the ultrafiltration unit comprises an ultrafiltration membrane and is used for removing colloidal nuclides in radioactive waste liquid;

the concentration unit comprises a reverse osmosis device, a water inlet of the reverse osmosis device is connected with a purified liquid outlet of the ultrafiltration unit, and the reverse osmosis device receives the purified liquid of the ultrafiltration unit so as to perform reverse osmosis concentration on the purified liquid of the ultrafiltration unit;

an ion exchange unit comprising an ion exchange bed, and a water inlet of the ion exchange unit is connected with a concentrate outlet of the reverse osmosis device, the ion exchange unit receiving the concentrate of the concentration unit to extract radionuclides enriched in the concentrate of the concentration unit to a solid phase.

The second aspect of the present invention provides a radioactive waste liquid treatment method, which includes the steps of:

a) removing colloidal nuclides in the radioactive waste liquid by using an ultrafiltration membrane;

b) performing reverse osmosis concentration on the radioactive waste liquid from which the radioactive nuclide is removed;

c) and extracting the radionuclides enriched by the concentrated solution of the concentration unit to a solid phase by using an ion exchanger.

According to the radioactive waste liquid treatment system and method provided by the invention, firstly, the colloidal nuclide in the radioactive waste liquid is removed by using the ultrafiltration membrane, so that the decrement of radioactive solid waste can be initially realized, meanwhile, the influence of the colloidal nuclide on the subsequent process can be reduced, the treatment efficiency of a reverse osmosis device and an ion exchange bed is improved, and the service life of the reverse osmosis device and the ion exchange bed is prolonged. Then concentrating the radioactive waste liquid, and extracting the radioactive nuclide in the concentrated solution to a solid phase by using an ion exchange bed, so that the adsorption capacity of the ion exchange resin can be fully utilized, and the generation amount of the radioactive ion exchange resin is minimized. Thus, the radioactive waste liquid treatment system and method of the present invention can minimize the generation of radioactive waste.

Drawings

Fig. 1 is a schematic structural diagram of a radioactive liquid waste treatment system according to an embodiment of the present invention.

Fig. 2 is a schematic view of an ultrafiltration cup apparatus according to an embodiment of the present invention.

Fig. 3 is a schematic structural diagram of another radioactive waste liquid treatment system according to an embodiment of the present invention.

Fig. 4 is a schematic structural diagram of another radioactive waste liquid treatment system according to an embodiment of the present invention.

Fig. 5 is a schematic structural diagram of another radioactive waste liquid treatment system according to an embodiment of the present invention.

FIG. 6 is a schematic diagram showing the membrane flux changes of ultrafiltration membrane I (a) and ultrafiltration membrane II (b) in the process of removing colloidal silver according to the embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantageous technical effects of the present invention more clear, the present invention is further described in detail with reference to the following embodiments. It should be understood that the embodiments described in this specification are only for the purpose of explaining the present invention and are not intended to limit the present invention.

For the sake of brevity, only some numerical ranges are explicitly disclosed herein. However, any lower limit may be combined with any upper limit to form ranges not explicitly recited; and any lower limit may be combined with any other lower limit to form a range not explicitly recited, and similarly any upper limit may be combined with any other upper limit to form a range not explicitly recited. Also, although not explicitly recited, each point or individual value between endpoints of a range is encompassed within the range. Thus, each point or individual value can form a range not explicitly recited as its own lower or upper limit in combination with any other point or individual value or in combination with other lower or upper limits.

In the description herein, it is noted that, unless otherwise specified, "a plurality" means one or more than one; "several" means two or more; the terms "above" and "below" are inclusive; the terms "upper", "lower", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present disclosure.

The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. The following description more particularly exemplifies illustrative embodiments. At various points throughout this application, guidance is provided through a list of embodiments that can be used in various combinations. In each instance, the list is merely a representative group and should not be construed as exhaustive.

First, a radioactive liquid waste treatment system according to a first aspect of the present invention will be described. Fig. 1 is a schematic configuration diagram of a radioactive liquid waste treatment system as an example. Referring to fig. 1, the radioactive liquid waste treatment system includes an ultrafiltration unit 10, a concentration unit 20, and an ion exchange unit 30.

The ultrafiltration unit 10 includes an ultrafiltration membrane for removing colloidal nuclides in radioactive waste liquid.

The concentration unit 20 includes a reverse osmosis device, and a water inlet of the reverse osmosis device is connected with a purified liquid outlet of the ultrafiltration unit 10, and the reverse osmosis device receives the purified liquid of the ultrafiltration unit 10 to perform reverse osmosis concentration on the purified liquid of the ultrafiltration unit 10.

The ion exchange unit 30 comprises an ion exchange bed, a water inlet of the ion exchange unit 30 is connected with a concentrated solution outlet of the reverse osmosis device, and the ion exchange unit 30 receives the concentrated solution of the concentration unit 20 to extract the radionuclide enriched in the concentrated solution of the concentration unit 20 to a solid phase.

The radioactive waste liquid treatment system provided by the invention firstly utilizes the ultrafiltration membrane to remove the colloidal nuclide in the radioactive waste liquid, can preliminarily realize the decrement of radioactive solid waste, can reduce the influence of the colloidal nuclide on the subsequent process, and improves the treatment efficiency and the service life of the reverse osmosis device and the ion exchange bed. And then concentrating the radioactive waste liquid by using a reverse osmosis device, and extracting the radioactive nuclide in the concentrated liquid to a solid phase by using an ion exchange bed, so that the adsorption capacity of the ion exchange resin can be fully utilized, and the generation amount of the radioactive ion exchange resin is minimized. Thus, the radioactive waste liquid treatment system of the present invention is employed to minimize the amount of radioactive solid waste generated.

In the radioactive liquid waste treatment system of the present invention, an ultrafiltration membrane known in the art can be used. In some preferred embodiments, the ultrafiltration membrane may comprise a polymer-based membrane and a polymer membrane layer disposed on the polymer-based membrane, the polymer membrane layer being grafted with a hydrophilic modifier.

The polymer-based film is not particularly limited and may be selected according to actual needs. For example, the polymer-based film is selected from nonwoven fabrics.

The polymer membrane layer may be a membrane material of an ultrafiltration membrane known in the art. By way of example, the membrane material may include one or more of polyvinylidene fluoride (PVDF), Polysulfone (PS), Polyethersulfone (PES), and Polyimide (PI). For example, the membrane material is polyvinylidene fluoride (PVDF). Further, the molecular weight of the membrane material may be 10 to 100 ten thousand g/mol, such as 45 to 55 ten thousand g/mol.

Hydrophilic groups are introduced into the ultrafiltration membrane modified by the hydrophilic modifier, so that the hydrophilicity of the ultrafiltration membrane can be improved, and meanwhile, the surface Zeta potential of the ultrafiltration membrane is improved, so that the pollution resistance and the adsorption performance to colloidal nuclide of the ultrafiltration membrane can be greatly improved. The ultrafiltration membrane has high removal rate on colloidal nuclides (such as colloidal silver and the like) and good long-term stability, so that the subsequent reverse osmosis unit and ion exchange unit have high treatment efficiency and long service life, and the yield of radioactive wastes is reduced.

In some embodiments, the hydrophilic group of the hydrophilic modifier may include one or more of a carboxyl group, a sulfonic acid group, a hydroxyl group, an amide group, and an amino group. Further, the hydrophilic group may include one or more of a carboxyl group and a sulfonic acid group. The proper hydrophilic group is selected, so that the surface Zeta potential of the ultrafiltration membrane can be further improved while the hydrophilicity of the ultrafiltration membrane is improved, and the pollution resistance and the adsorption performance of the ultrafiltration membrane are improved. As an example, the hydrophilic group includes or is a carboxyl group.

In some embodiments, the hydrophilic modifier can be selected from an olefinic modifier containing a hydrophilic group. The olefinic modifier has C ═ C bonds, has high reactivity, and can graft more modifier on a polymer membrane material under the irradiation condition, so that the ultrafiltration membrane has more hydrophilic groups, and the surface performance of the ultrafiltration membrane is improved better.

By way of example, the hydrophilic modifier may be selected from one or more of Acrylic Acid (AA), acrylic sulfonic acid, hydroxyethyl methacrylate (HEMA), Acrylamide (AM), allylamine, and the like. Further can be one or more of Acrylic Acid (AA) and propylene sulfonic acid. For example, the hydrophilic modifier includes or is Acrylic Acid (AA).

In some embodiments, the ultrafiltration membrane has a water contact angle ≦ 70. For example, the ultrafiltration membrane has a water contact angle of 62 °, 64 °, 65 °, 66 °, 68 °, or the like. The water contact angle of the ultrafiltration membrane is smaller, which shows that the surface hydrophilicity of the ultrafiltration membrane is better, the pollution resistance of the ultrafiltration membrane is stronger, and the reduction of the output of radioactive wastes is facilitated.

Ultrafiltration membranes can be tested for water contact angle using instruments and methods known in the art. For example, using a contact angle measuring instrument (e.g., model SL200KS, Keno, USA). After the ultrafiltration membrane sample was dried in advance, the contact angle of pure water (ultrapure water, purity 18.2 M.OMEGA.. multidot.cm) was measured, the droplet size was 1. mu.L, and the value of the 5 th s was selected as the value of the contact angle of the ultrafiltration membrane sample. Each sample was measured 6 times at different locations and averaged.

In some embodiments, the surface Zeta potential of the ultrafiltration membrane at pH 7 is ≧ 15mV, preferably ≧ 12.5 mV. For example, the surface Zeta potential of the ultrafiltration membrane at pH 7 is-12.5 mV, -12mV, -11mV, -10mV, -8mV, or-7 mV, etc. The ultrafiltration membrane has higher surface Zeta potential, and can obtain better adsorption performance, thereby further improving the removal effect of colloidal nuclide.

The surface Zeta potential of ultrafiltration membranes can be tested using instruments and methods known in the art. For example using a Zeta potentiometer (e.g., Anton Paar surf pass 3).

In some embodiments, the ultrafiltration membrane has a pure water membrane flux of 50 L.m at a transmembrane pressure difference of 0.1MPa^-2·h^-1～600L·m^-2·h^-1Further, it may be 200 L.m^-2·h^-1～600L·m^-2·h^-1Or 500 L.m^-2·h^-1～600L·m^-2·h^-1. For example, the pure water membrane flux of the ultrafiltration membrane is 150 L.m at a transmembrane pressure difference of 0.1MPa^-2·h^-1、200L·m^-2·h^-1、250L·m^-2·h^-1、300L·m^-2·h^-1、350L·m^-2·h^-1、400L·m^-2·h^-1、450L·m^-2·h^-1、500L·m^-2·h^-1Or 550 L.m^-2·h^-1And the like. The ultrafiltration membrane has higher membrane flux and can improve the treatment efficiency of the radioactive waste liquid.

The ultrafiltration cup device was used for membrane flux testing and the schematic diagram of the device is shown in FIG. 2. The device adopts a constant-pressure dead-end filtration mode, pressure is provided by a nitrogen bottle, liquid (such as ultrapure water, the purity is 18.2M omega cm) in a water storage tank is pressed into an ultrafiltration cup, the liquid enters a beaker through an ultrafiltration membrane at the bottom of the ultrafiltration cup, and an electronic balance (Mettler Toledo ME204) records the quality of the beaker at regular time and sends the quality to a computer. The mass of the liquid flowing through the ultrafiltration membrane can be known by calculating the difference value of the scale readings in a certain time interval, and then the membrane flux can be calculated. After the device starts to operate, firstly, a membrane pre-pressing process is carried out for 30min under twice test pressure, then, the pressure is controlled at the test pressure (such as 0.1MPa), and flux values are recorded after the membrane flux is stable. The test water temperature was 25 ℃. The formula for calculating the membrane flux is as follows:

wherein J is the membrane flux (L.m)^-2·h^-1) (ii) a Δ t is the time interval (h); m is the mass (g) of liquid passing through the membrane over Δ t; a is the membrane area (m)²)；ρIs liquid density (g.L)^-1) And is recorded as 1000 g.L in this test^-1。

In some embodiments, the polymer membrane layer of the ultrafiltration membrane may be grafted with the hydrophilic modifier by co-irradiating the membrane material of the polymer membrane layer, the porogen and the hydrophilic modifier. For example, the membrane material, porogen and hydrophilic modifier may be dispersed in the same solution system and subjected to irradiation. The hydrophilic modifier can generate free radicals under irradiation, and hydrophilic groups are introduced into the membrane material by grafting the free radicals onto active points of the polymer. And then preparing a polymer membrane layer on the polymer base membrane by taking the obtained mixed solution as a membrane casting solution to obtain the ultrafiltration membrane. The ultrafiltration membrane has obviously improved hydrophilicity and simultaneously has higher surface Zeta potential. And the hydrophilic modifier is connected to the membrane material through chemical bonding, so that hydrophilic groups are stably present in the ultrafiltration membrane, and the hydrophilic modification effect on the ultrafiltration membrane is more stable.

As an example, the ultrafiltration membrane can be prepared by the following preparation method: a step of preparing a mixed solution S10, a radiation irradiation step S20, and a wet phase inversion step S30.

S10, dissolving the polymer membrane material, the pore-forming agent and the hydrophilic modifier in an organic solvent to obtain a mixed solution.

At S10, the polymeric membrane material and the hydrophilic modifier may be the membrane material described herein. The polymer film material is, for example, PVDF. The hydrophilic modifier is, for example, acrylic acid.

At S10, a porogen known in the art may be used. For example, the porogen may comprise one or more of polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG). The polymer film layer can form a proper film pore structure by adopting a proper pore-foaming agent, the film flux of the ultrafiltration film is improved, and the polymer film layer can exist in the polymer film layer partially through chemical bonding (such as chemical bonding initiated by generating free radicals under irradiation) and/or affinity action (such as hydrogen bond and the like), so that the surface performance of the ultrafiltration film is improved, such as the surface hydrophilicity and the surface Zeta potential are improved. By way of example, the porogen may comprise or be PVP. Further, the molecular weight of the porogen may be 1 to 10 ten thousand g/mol, such as 4 to 6 ten thousand g/mol.

At S10, the organic solvent may be a solvent for dissolving the polymer film material, which is well known in the art. For example, the organic solvent may be selected from CCl₄One or more of N, N-Dimethylacetamide (DMAC), N-Dimethylformamide (DMF) and the like. By way of example, the organic solvent comprises DMAC.

In some preferred embodiments, the mass of the porogen in the mixed solution is positively correlated with the mass of the hydrophilic modifier at S10. The use amount of the hydrophilic modifier is increased in a reasonable range, so that the surface hydrophilicity and the surface Zeta potential of the ultrafiltration membrane can be improved, and the pollution resistance of the ultrafiltration membrane is further improved. Meanwhile, the usage amount of the pore-foaming agent is increased along with the increase of the hydrophilic modifier, and the membrane pores are prevented from being covered, extruded and blocked due to the increase of the modifier, so that the ultrafiltration membrane can obtain a better membrane pore structure, and the ultrafiltration membrane also has higher membrane flux. Preferably, the mass ratio of the pore-foaming agent to the hydrophilic modifier in the mixed solution is 3: 1-7: 1, more preferably 4: 1-6: 1, such as 5: 1.

In some preferred embodiments, at S10, the porogen may be included in the mixed solution in an amount of 0.1% to 5% by mass, and further in an amount of 3% to 5% by mass. The content of the hydrophilic modifier in the mixed solution may be 0.3% to 1.5% by mass, and further may be 0.5% to 1.2% by mass, or 0.6% to 1% by mass. The mass percentage content of the polymer film material in the mixed solution can be 15-25%, and further can be 18-20%.

As a specific example, the mixed solution is DMAC as a solvent, which may contain 18% PVDF, 3% PVP, and 0.6% AA. As another example, the mixed solution is DMAC in solvent, which may contain 18% PVDF, 5% PVP, and 1% AA.

At S10, stirring may be carried out at 30 ℃ to 50 ℃, for example 40 ℃, in order to promote dissolution of the material. The stirring is, for example, shaking. The rate of oscillation may be between 80 rpm and 130 rpm, such as 110 rpm. The oscillation time can be 30-50 h. By reasonably regulating and controlling the oscillation process, the materials can be fully dissolved, and meanwhile, the prepared mixed solution does not contain or basically does not contain bubbles, so that the uniformity and the consistency of the polymer film layer are ensured. The shaking process may be performed in an oven.

And S20, irradiating the mixed solution to graft the hydrophilic modifier on the polymer membrane material to obtain the membrane casting solution.

Through irradiation of the mixed solution, more hydrophilic modifier can be grafted on the polymer membrane material, so that more hydrophilic groups are introduced into the ultrafiltration membrane, and the hydrophilicity and the surface Zeta potential of the ultrafiltration membrane can be further improved.

At S20, the radiation irradiation may use ultraviolet rays, β rays, gamma rays, X rays, α rays or neutron rays⁶⁰Co rays. The radiation dose rate of the radiation exposure may be 220Gy/min to 230Gy/min, such as 223 Gy/min. The radiation dose of the radiation irradiation may be 10kGy to 15 kGy. The ambient temperature of the radiation irradiation may be normal temperature (25 + -3 deg.C).

And S30, forming a polymer membrane layer on the polymer base membrane by the membrane casting solution through a wet phase inversion method to obtain the ultrafiltration membrane, wherein the polymer membrane layer is grafted with a hydrophilic modifier.

In S30, the casting solution may be applied to the surface of the polymer-based film; then standing for 0-30 s, such as 10-20 s, at the normal temperature (25 +/-3 ℃); and then soaking the membrane into a coagulant to perform phase inversion on the coating film of the membrane casting solution to form a porous and hydrophilic modified polymer membrane layer, thus obtaining the ultrafiltration membrane. Wherein a coagulant known in the art, such as deionized water, may be employed. The temperature of the phase inversion may be from 20 ℃ to 30 ℃, such as 25 ℃. The phase inversion time may be 5min to 15min, such as 10 min.

As a specific example, the nonwoven fabric may be smoothly fixed on the glass plate with a waterproof transparent adhesive tape at S30; and pouring the casting solution onto non-woven fabric, and coating the casting solution into a thin film by using a scraper. The coating thickness may be from 100 μm to 250 μm, for example from 150 μm to 200 μm. Then standing for 10-20 s at normal temperature (25 +/-3 ℃); then immersing the membrane into deionized water at the temperature of 20-25 ℃ to carry out phase conversion on the coating of the membrane casting solution for 10-15 min; then, the ultrafiltration membrane can be repeatedly rinsed by deionized water as required, surface residues (such as organic solvent, PVP and the like) are removed, and the glass plate is taken out to obtain the ultrafiltration membrane.

The ultrafiltration membrane prepared by the preparation method can obtain higher hydrophilicity and surface adsorption performance under larger membrane flux. Particularly, the ultrafiltration membrane has higher removal capacity per unit area for colloidal nuclide, especially has higher adsorption capacity per unit area for colloidal nuclide under larger membrane flux.

Colloidal nuclides in the radioactive waste liquid are removed through the ultrafiltration membrane, so that chemical agents can be prevented from being added, and the reduction of radioactive solid wastes is favorably realized.

In some embodiments, the concentrate of the ultrafiltration unit 10 may be returned to the water inlet of the ultrafiltration unit 10, merged with the radioactive spent solution and then processed in the ultrafiltration unit 10. In these embodiments, the concentrate outlet of the ultrafiltration unit 10 may be connected to the water inlet of the ultrafiltration unit 10.

The concentration unit 20 may employ reverse osmosis devices known in the art, and may be selected and configured as desired by those skilled in the art.

In some embodiments, the concentration unit 20 may be provided with a primary reverse osmosis device. The reverse osmosis device can be one section or more than two sections of reverse osmosis, namely, a one-section reverse osmosis membrane module or more than two sections (such as two sections, three sections and the like) of reverse osmosis membrane modules can be adopted. When more than two sections of reverse osmosis membrane modules are adopted, the concentrated solution produced by the previous section of reverse osmosis membrane module is used as the inlet water of the next section of reverse osmosis membrane module, and the concentrated solution produced by the last section of reverse osmosis membrane module is used as the concentrated solution of the reverse osmosis device and sent to the ion exchange unit 30 for treatment. And the purified liquid generated by all the reverse osmosis membrane components is converged into the purified liquid of the reverse osmosis device.

Alternatively, the reverse osmosis membrane may be a Dow BW30 model reverse osmosis membrane.

In some embodiments, the concentration ratio of the concentration unit 20 to concentrate the radioactive waste liquid treated by the ultrafiltration unit 10 may be 2 to 10 times, and further may be 3 to 5 times.

The ion exchange unit 30 may employ ion exchange beds known in the art, such as ion exchange resin beds. The ion exchange resin has a good effect of removing the ionic radionuclide.

In some embodiments, the ion exchange resin bed may be a mixed bed comprising a strongly acidic ion exchange resin (e.g., a sulfonic acid group cation exchange resin, etc.) and a strongly basic ion exchange resin (e.g., a quaternary amine group anion exchange resin, etc.). Further, the ion exchange resin bed may be an IRN160 mixed resin bed. The IRN160 mixed resin bed is formed by proportionally mixing cation exchange resin IRN97 and anion exchange resin IRN 78. IRN97 is H-type polystyrene-divinylbenzene polymer with sulfonic acid group, and has a total exchange capacity of 2.15 eq.L^-1. IRN78 is an OH-type polystyrene-divinylbenzene polymer with trimethylamine group and a total exchange capacity of 1.10 eq.L^-1。

In some embodiments, the ion exchange unit 30 may be provided with one or more than two (e.g., two, three, etc.) ion exchange resin beds. As one example, the ion exchange unit 30 may include two ion exchange resin beds connected in series in sequence.

Fig. 3 shows a radioactive liquid waste treatment system as another example. Referring to fig. 3, in some embodiments, the water outlet of the ion exchange unit 20 is connected to the water inlet of the reverse osmosis device such that liquid passing through the ion exchange unit 20 is returned to the reverse osmosis device. Thus, the water treated by the ion exchange unit 20 and the purified liquid of the ultrafiltration unit 10 are merged and enter the reverse osmosis device for reverse osmosis concentration treatment. This can reduce the amount of radioactive solid waste produced to a greater extent.

In some embodiments, any of the radioactive liquid waste treatment systems may further include a deep purification unit 40, and a water inlet of the deep purification unit 40 is connected to a purified liquid outlet of the concentration unit 30. The deep purification unit 40 receives the purified liquid from the concentration unit 30, and performs deep purification on the purified liquid to remove the radionuclides therein, so that the effluent meets or even exceeds the discharge standard (i.e., for coastal sites, the specific discharge activity of the radionuclides should not exceed 1000 Bq. L)^-1(ii) a For inlandThe specific activity of the radioactive nuclide emission of the plant site should not exceed 100 Bq.L^-1)。

The deep purification unit 40 may employ one or more of a reverse osmosis device and a continuous electric demineralization device. In some embodiments, the deep purification unit 40 may include a reverse osmosis sub-unit 41 and a continuous electric desalination sub-unit 42.

The water inlet of the reverse osmosis subunit 41 is connected with the purified liquid outlet of the reverse osmosis device of the concentration unit 20, and the concentrated liquid outlet of the reverse osmosis subunit 41 is connected with the water inlet of the reverse osmosis device of the concentration unit 20.

The reverse osmosis sub-unit 41 may be provided with one or two stages of reverse osmosis devices. The reverse osmosis unit may be a reverse osmosis unit as described hereinbefore.

The water inlet of the continuous electric desalting subunit 42 is connected with the purified liquid outlet of the reverse osmosis subunit 41, and the concentrated liquid outlet of the continuous electric desalting subunit 42 is connected with the water inlet of the reverse osmosis device of the concentration unit 20.

The continuous electric desalting sub-unit 42 may be provided with one-stage or two-stage continuous electric desalting means. The continuous electric demineralization apparatus may be a continuous electric demineralization apparatus for removing radionuclides known in the art.

As an example, the deep purification unit 40 may include a reverse osmosis unit, a first stage continuous electric desalination device, and a second stage continuous electric desalination device connected in series in that order.

The liquid treated by the deep purification unit 40 can meet or even exceed the discharge standard. In addition, the radioactive waste liquid treatment system of the invention does not basically generate radioactive concentrated liquid, and can further reduce the generation amount of radioactive waste.

Fig. 4 shows a radioactive liquid waste treatment system as another example. Referring to fig. 4, in some embodiments, the water outlet of the ion exchange unit 30 is connected to the purified liquid outlet of the deep purification unit 40, so that the liquid passing through the ion exchange unit 30 and the purified liquid of the deep purification unit 40 are merged and then discharged. This reduces the system operating pressure and energy consumption while reducing the amount of radioactive solid waste produced.

Fig. 5 shows a radioactive liquid waste treatment system as another example. Referring to fig. 5, in some embodiments, the water outlet of the ion exchange unit 30 is connected with the water inlet of the reverse osmosis apparatus of the concentration unit 20, and the water outlet of the ion exchange unit 30 is connected with the purified liquid outlet of the deep purification unit 40. Thus, a part of the liquid treated by the ion exchange unit 30 is returned to the reverse osmosis device of the concentration unit 20, and the other part of the liquid is merged with the purified liquid of the deep purification unit 30 and then discharged. This can further reduce the amount of radioactive solid waste produced at a lower system operating pressure and energy consumption.

In these embodiments, the ratio of the liquid treated by the ion exchange unit 30 to enter the concentration unit 20 and the deep purification unit 40 can be determined according to actual needs. As an example, the liquid discharged from the ion exchange unit 30 at the previous stage may be merged with the purification liquid of the deep purification unit 30 and then discharged; the liquid discharged in the later stage is merged with the purified liquid of the ultrafiltration unit 10 and then enters the concentration unit 20. The early stage and the late stage can be determined by those skilled in the art according to whether the final effluent of the system meets the purification requirements.

In some embodiments, the radioactive waste treatment system can further include a cesium adsorption device. The cesium ions in the waste liquid are removed by the cesium adsorption device, and the radionuclide removal rate of the system can be further improved.

The cesium adsorption device may be disposed upstream of the ion exchange bed. For example, the concentrate from the concentration unit 20 is passed through a cesium adsorption unit and then through an ion exchange bed. Therefore, the radionuclide Cs in the concentrated solution can be adsorbed by the cesium adsorption device, and then the radionuclide in the concentrated solution can be further removed by the ion exchange bed, so that the radionuclide removal effect can be further improved, and the generation amount of radioactive solid waste can be further reduced.

The cesium adsorption unit may also be placed at the outer discharge end of the system. For example, the water inlet of the cesium adsorption device is connected to the purified liquid outlet of the deep purification unit 40. And (4) sending the liquid after passing through the deep purification unit 40 to a cesium adsorption device for cesium removal and then discharging. For another example, the water outlet of the ion exchange unit 20 is connected to the purified liquid outlet of the deep purification unit 40, and the water inlet of the cesium adsorption device is connected to the water outlet of the ion exchange unit 20 and the purified liquid outlet of the deep purification unit 40, respectively. The liquid passing through the ion exchange unit 20 is merged with the purified liquid of the deep purification unit 40, and then sent to a cesium adsorption device for cesium removal and then discharged.

The cesium adsorption apparatus may employ an adsorbent known in the art for removing cesium. By way of example, the cesium adsorption means may comprise one or more of zeolite, ferrocyanide-loaded silica, and ferrocyanide-loaded alumina. For example, the cesium adsorption unit includes a zeolite bed.

In the radioactive liquid waste treatment system of the present invention, a pretreatment unit is optionally further provided before the ultrafiltration unit 10. The pretreatment unit can be used for removing suspended matters such as oil, particles and other impurities in radioactive waste liquid. Thus, the pretreatment unit may include one or a combination of two or more of an oil-water separator, an activated carbon filter, a microfiltration device, a paper core filter, and a self-cleaning filter, but is not limited thereto. Pretreatment by the pretreatment unit may facilitate the processing of subsequent units.

Next, a radioactive liquid waste treatment method according to a second aspect of the present invention is explained, which comprises the steps of:

s100, removing colloidal nuclides in radioactive waste liquid by using an ultrafiltration membrane;

s200, performing reverse osmosis concentration on the radioactive waste liquid from which the radioactive nuclide is removed;

s300, extracting the radionuclide enriched in the concentrated solution of the concentration unit to a solid phase by using an ion exchanger.

The method for treating the radioactive waste liquid provided by the invention firstly utilizes the ultrafiltration membrane to remove the colloidal nuclide in the radioactive waste liquid, can preliminarily realize the decrement of radioactive solid waste, can reduce the influence of the colloidal nuclide on the subsequent process, and improves the treatment efficiency and the service life of a reverse osmosis device and an ion exchanger. And then concentrating the radioactive waste liquid by using a reverse osmosis device, and extracting the radioactive nuclide in the concentrated liquid to a solid phase by using an ion exchange bed, so that the adsorption capacity of the ion exchanger can be fully utilized, and the generation amount of the radioactive ion exchanger is minimized. Thus, the radioactive waste liquid treatment method of the present invention minimizes the amount of radioactive solid waste generated.

The ultrafiltration membrane described above may be used at S100.

In some embodiments, the concentrated solution generated in the ultrafiltration step of S100 may be used as the influent water of the ultrafiltration step, and the concentrated solution may be combined with the influent water of the radioactive waste liquid for ultrafiltration treatment.

S200 may be performed using a reverse osmosis apparatus as described previously.

In some embodiments, the concentration factor of the reverse osmosis concentration in S200 may be 2 to 10 times, and further may be 3 to 5 times.

At S300, ion exchange beds as described above may be employed.

In some embodiments, the purified liquid produced in S300 is returned to S200. That is, the liquid treated in the ion exchange step S300 is merged with the purified liquid produced in the ultrafiltration step S100, and then subjected to reverse osmosis concentration. This can reduce the amount of radioactive solid waste produced to a greater extent.

In some embodiments, the method further comprises: and S400, deeply purifying the purified liquid generated in the S200. In S400, the radioactive nuclide in the liquid is removed through deep purification, so that the liquid meets or even exceeds the discharge standard.

The deep purification unit 40 may employ one or more of a reverse osmosis device and a continuous electric demineralization device. In some embodiments, the deep purification unit 40 may include a reverse osmosis sub-unit 41 and a continuous electrodeionization sub-unit 42 as previously described.

In some embodiments, the purified liquid generated in S300 is merged with the purified liquid generated in S400 and then discharged. This reduces the system operating pressure and energy consumption while reducing the amount of radioactive solid waste produced.

In some embodiments, a portion of the purified liquid generated in S300 is returned to S200, and another portion is merged with the purified liquid generated in S400 and discharged. This can further reduce the amount of radioactive solid waste produced at a lower system operating pressure and energy consumption.

Other technical features of the radioactive waste liquid treatment system of the first aspect of the present invention are also applicable to the radioactive waste liquid treatment method of the second aspect of the present invention, and will not be described herein again.

The radioactive waste treatment system and method of the present invention may include the following advantages: 1) the method can realize the efficient removal of the colloid state and ionic state radioactive nuclide in the process waste liquid, and the effluent can reach the standard and be discharged; 2) compared with the chemical flocculation, adsorption and ion exchange processes used in the current nuclear power plant, the method can realize the reduction of radioactive solid wastes; 3) no chemical agent is added, so that secondary pollution is avoided; 4) the concentrated solution is not discharged outwards, and all liquid effluents can be directly discharged.