阅读说明：本技术 一种放射性综合废水的处理方法 (Method for treating radioactive comprehensive wastewater ) 是由 徐乐昌 吴名涛 周磊 牛洁 邓锦勋 于 2021-01-12 设计创作，主要内容包括：本发明提供了一种放射性综合废水的方法,利用沉淀剂分离放射性铀,电氧化处理中间废水,在使废水能够达标排放的前提下,进一步降低污染物浓度。去除铀后,能够进一步去除废水中的锰、氨氮和COD,完成废水处理。工艺简单,设备要求低,无需额外添加处理剂,不会产生二次污染,能够进行批量处理,满足工业生产的需求。(The invention provides a method for radioactive comprehensive wastewater, which utilizes a precipitator to separate radioactive uranium and carries out electrooxidation treatment on intermediate wastewater, thereby further reducing the concentration of pollutants on the premise of enabling the wastewater to reach the standard for discharge. After uranium is removed, manganese, ammonia nitrogen and COD in the wastewater can be further removed, and wastewater treatment is completed. The method has the advantages of simple process, low equipment requirement, no need of extra treatment agent, no secondary pollution, capability of batch treatment and capability of meeting the requirements of industrial production.)

1. The method for treating the radioactive comprehensive wastewater is characterized in that uranium in the radioactive comprehensive wastewater is separated by using a precipitator and then is subjected to electrooxidation treatment.

2. The method according to claim 1, wherein the method is used for treating radioactive comprehensive wastewater containing uranium, manganese, inorganic ammonia nitrogen and COD.

3. The method according to claim 1 or 2, characterized in that it comprises in particular the steps of:

step 1, adding a precipitator into the wastewater, and separating precipitates to obtain intermediate wastewater;

step 2, carrying out electrooxidation treatment on the intermediate wastewater;

and 3, discharging the wastewater after the electrooxidation treatment into a secondary sedimentation tank, and performing sedimentation separation to obtain the treated wastewater.

4. The method according to any one of claims 1 to 3, wherein in step 1, the precipitating agent is selected from one or more of hydroxides, calcium salts or calcium oxides, preferably from one or more of carbide slag, limestone, calcium oxide, strong bases, calcium peroxide and calcium hydroxide.

5. The method according to any one of claims 1 to 4, wherein the pH of the radioactive comprehensive waste water after the adjustment in step 1 is 7.5 to 11.

6. The method according to any one of claims 1 to 5, wherein in step 2, the current density of the electrolytic cell is 5-35mA/cm²。

7. The method according to any one of claims 1 to 5, characterized in that in step 2, the electrolytic cellThe current density of (A) is 10-30mA/cm²。

8. The method according to any one of claims 1 to 7, wherein the electrolytic cell anode plate is selected from graphite electrodes or coated titanium anodes, preferably coated titanium anodes, more preferably Ti/RuO₂-IrO₂Anodes or Ti/RuO₂-IrO₂-SnO₂And an anode.

9. The method according to any one of claims 1 to 8, wherein the manganese ion content is 2-90mg/L, preferably 6-70mg/L, more preferably 10-50 mg/L.

10. The method according to any one of claims 1 to 9, wherein the radioactive comprehensive waste water has a chloride ion content of 0.5 to 8g/L, preferably 1 to 4 g/L.

Technical Field

The invention belongs to the technical field of radioactive wastewater treatment, and particularly relates to a method for treating radioactive comprehensive wastewater.

Background

In the early uranium mining and uranium industrial production process, a large amount of solid wastes are generated, and are stored uniformly due to radioactivity, particularly in a uranium tailing pond during uranium mining. After the tailings pond is in service, the tailings pond needs to be subjected to retirement treatment, a large amount of wastewater is generated in the retirement treatment process of the tailings pond, and covering treatment can be performed only after surface water and pore water of tailings are removed in the retirement beach surface treatment process. On the premise of ensuring the safety of the upper covering layer, the mechanical equipment can enter the field for construction. And the phenomenon of differential settlement after treatment can be avoided only by fully removing pore water, so that the long-term stability of the covering layer is guaranteed.

Partial tailing pond seepage drainage has the characteristics of large water volume, radioactivity, high uranium, high manganese, high ammonia nitrogen and high salinity. If the uranium-bearing waste water directly enters the water body, the uranium-bearing waste water can possibly have adverse effects on human health and ecological environment, and the uranium-bearing waste water needs to be treated to reach the standard before being discharged. The common uranium removal methods at present comprise adsorption treatment, ion exchange, chemical precipitation, solvent extraction and the like, can not meet the requirements of actual treatment, and can introduce organic matters and the like by using an extraction method.

In addition, when the manganese is excessive, hyperthyroidism of human beings can be caused, important organs are damaged, the water eutrophication can be caused by ammonia nitrogen and COD, and the excessive ammonia nitrogen is an important factor for causing abnormal proliferation of algae and microorganisms in the water.

Therefore, in the process of treating the beach surface of the tailing pond and the like, over-standard seepage and drainage water is generated, and the seepage and drainage water can be discharged after reaching the standard after being treated. Therefore, a new process for removing uranium, manganese, ammonia nitrogen and COD is urgently needed.

Disclosure of Invention

In order to solve the problems, the inventor of the invention carries out intensive research to obtain a method for treating radioactive comprehensive wastewater, uranium is separated from the wastewater, an electrooxidation process is designed to achieve the purpose of removing manganese, ammonia nitrogen and COD in the wastewater, after treatment, the discharge standard can be reached, the concentration of pollutants in the wastewater is further reduced compared with the traditional process, and the requirements of industrial production can be met, thereby completing the invention.

The invention aims to provide a method for treating radioactive comprehensive wastewater, which separates uranium in the radioactive comprehensive wastewater by using a precipitator and then carries out electrooxidation treatment.

The method is used for treating radioactive comprehensive wastewater which contains uranium, manganese ions, inorganic ammonia nitrogen and COD.

The method specifically comprises the following steps:

step 1, adding a precipitator into the wastewater, and separating precipitates to obtain intermediate wastewater;

step 2, carrying out electrooxidation treatment on the intermediate wastewater;

and 3, discharging the wastewater after the electrooxidation treatment into a secondary sedimentation tank, and performing sedimentation separation to obtain the treated wastewater.

The method for radiating comprehensive wastewater provided by the invention has the following beneficial effects:

(1) the wastewater treatment method provided by the invention mainly aims at radioactive comprehensive wastewater, has complex water quality, can greatly reduce the generation amount of radioactive precipitates, removes manganese-containing substances, ammonia nitrogen and COD in the wastewater in one step, completes wastewater treatment and reaches the discharge standard.

(2) By utilizing the treatment method, the separated manganese precipitate has high purity, can directly enter a recovery process, and simplifies the process of secondary treatment of the composite isolate.

(3) The treatment method has simple process, the generated separation product can be absorbed by alkali liquor, nitrogen can be directly discharged, the equipment requirement is low, no additional treatment agent is required, the treatment capacity is large, and large-scale treatment can be realized.

Detailed Description

The present invention will now be described in detail by way of specific embodiments, and features and advantages of the present invention will become more apparent and apparent from the following description.

The method aims at treating the radioactive comprehensive wastewater which is high in uranium and manganese and contains ammonia nitrogen and COD, separating radioactive substances, and synchronously treating various pollutants through electrooxidation.

The radioactive comprehensive wastewater in the invention mainly comes from the links of uranium ore mining, tailing seepage drainage, uranium smelting production and the like, the water quality is complex, pollutants such as uranium, manganese, ammonia nitrogen, COD and the like are contained in the radioactive comprehensive wastewater, the existing wastewater treatment process is complex, the condition is strictly controlled, and secondary wastes are easily generated.

The invention provides a method for treating radioactive comprehensive wastewater, which separates uranium in the radioactive comprehensive wastewater by using a precipitator and then carries out electrooxidation treatment, and specifically comprises the following steps:

step 1, adding a precipitator into the wastewater, and separating precipitates to obtain intermediate wastewater.

In the invention, radioactive comprehensive wastewater is treated, and the comprehensive wastewater contains uranium, manganese, inorganic ammonia nitrogen and COD.

In the invention, the uranium concentration in the radioactive comprehensive wastewater is 2-170mg/L, preferably 4-90mg/L, and more preferably 6-10 mg/L; the content of manganese ions is 2-90mg/L, preferably 6-70mg/L, and more preferably 10-50 mg/L; the content of the inorganic ammonia nitrogen is 50-450mg/L, preferably 60-500mg/L, more preferably 100-400 mg/L; the COD concentration is 120-330mg/L, preferably 160-230 mg/L.

And (2) introducing the radioactive comprehensive wastewater into a uranium removal sedimentation tank, and adding a precipitator into the wastewater, wherein the precipitator is selected from one or more of hydroxides, calcium salts or calcium oxides, preferably one or more of carbide slag, limestone, calcium oxide, strong base, calcium peroxide and calcium hydroxide, and more preferably strong base and/or carbide slag such as flake caustic soda. After the addition of the precipitant, the reaction is preferably carried out under stirring or ultrasonic conditions. The reaction time is 0.2h-20h, preferably 0.5h-1.0h, and the reaction temperature is 4-32 ℃, preferably 15-25 ℃.

Adding a pH regulator into the wastewater, wherein the pH regulator comprises an acidic regulator and an alkaline regulator. The acidity regulator is selected from one or more of inorganic acids, preferably one or more of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid, and more preferably hydrochloric acid. The alkaline modifier is selected from the group consisting of the precipitating agents. The strong bases such as sodium hydroxide and caustic soda flakes can be quickly adjusted, the solubility of the carbide slag in a water system is low, the carbide slag is slowly adjusted after the pH value of the wastewater changes, in addition, the carbide slag and caustic soda flakes are wide in source and low in raw material cost, and the treatment cost of radioactive wastewater is greatly reduced.

After adding the precipitant and/or pH regulator, the pH value of the radioactive comprehensive waste water is 7.5-11, preferably 9-10.

The average particle size of the precipitant is 0.01-2mm, preferably 0.1-1.5 mm. The particle size of the precipitant can directly affect its activity and its dispersion in the wastewater. The precipitant keeps in above-mentioned particle diameter within range, can produce better dispersion effect in the waste water is synthesized to the radioactivity, reduces the reunion, makes stable the going on of process that subsides of uranium, is favorable to improving the effect that subsides of uranium.

In the invention, after a precipitator and/or a pH regulator is added, uranium and part of manganese in the wastewater are precipitated in an alkaline environment.

In addition, in the invention, the comprehensive wastewater quality is complex, and the pH value has various influences on the wastewater treatment process. On the one hand, the sedimentation of uranium is directly influenced to waste water pH value, and on the other hand, waste water pH value is controlled, and on the premise of guaranteeing that uranium subsides, the precipitation of minimize manganese to reduce the total amount of radioactive substance.

In the subsequent electro-oxidation process, the pH value of the comprehensive wastewater directly influences the oxidation and sedimentation of the residual manganese ions in the wastewater. Under different pH value environments, the content of oxidative active substances in the wastewater is different, the existence forms of ammonia nitrogen are also different, and the oxidation-reduction potential of the ammonia nitrogen is also changed, so that the treatment efficiency is improved and the final content of pollutants is reduced under the alkaline environment.

However, too strong alkalinity can reduce the content of active chlorine in the wastewater, thereby seriously affecting the removal effect of manganese and ammonia nitrogen. Meanwhile, the activity of active chlorine also influences the electro-oxidation process of COD. Therefore, in the present invention, the adjustment process of the pH of the integrated waste liquid needs to be strictly controlled.

Adding precipitant and/or pH regulator, and separating insoluble substance. The separation method is filtration, and optionally, a filter press is used for separation.

And 2, carrying out electrooxidation treatment on the intermediate wastewater.

And (4) leading the intermediate wastewater into an electrolytic cell for electrooxidation treatment. The electrolytic cell comprises a cell body, an anode plate and a cathode plate. The anode plate of the electrolytic cell is selected from a graphite electrode or a coating titanium anode(DSA plate), preferably a coated titanium anode, more preferably Ti/RuO₂-IrO₂Anodes or Ti/RuO₂-IrO₂-SnO₂Compared with other existing electrodes, the anode using graphite and the coated titanium anode can promote electrooxidation to remove pollutants in sewage, and particularly, the coated titanium anode can further reduce the content of pollutants in the sewage. The cathode plate is selected from a stainless steel cathode plate or a titanium mesh.

The current density of the electrolytic cell is 5-35mA/cm²Preferably 10-30mA/cm²More preferably 15 to 25mA/cm². The higher the current density is, the faster the transfer rate of electrons between the electrode and ammonia nitrogen in the wastewater is, the more active intermediate products with oxidation generated in a unit are, and the better the ammonia nitrogen removal effect is; however, the current density increases to a certain extent, the processing rate tends to be stable, and the energy consumption is increased by the excessive current density.

The area of the anode and cathode plates of the electrolytic cell is 8-20cm, preferably 10-15cm, to the distance between the plates.

In the radioactive comprehensive wastewater of the present invention, a large amount of chloride ions are generally present, and thus, in the electro-oxidation process, chemical substances having a strong oxidation potential, such as Cl, are generated₂、O₂、OCl^-And OH. Cl in solution^-Cl will be generated after anode of the polar plate is oxidized^-→Cl₂→OCl^-→Cl^-The cyclic reaction of the step (2) to generate a large amount of oxidation active intermediate products, and the oxidation of the residual divalent manganese ions, inorganic ammonia nitrogen and COD in the wastewater is completed.

In the invention, the content of chloride ions in the radioactive comprehensive wastewater is 0.5-8g/L, preferably 1-4g/L, and more preferably 1.5-2.5 g/L. In the comprehensive wastewater of the invention, a certain amount of chlorine exists, which can provide active chlorine in the subsequent treatment process and is more suitable for treatment by using an electrooxidation process.

In the electro-oxidation process, along with the increase of the concentration of chloride ions, the generated active substances are increased, which is beneficial to improving the treatment rate and promoting the reduction of various pollutants in the comprehensive wastewater. However, as the concentration of chloride ions is further increased, the treatment rate is decreased, presumably because the generated active chloride is not completely used for oxidizing ammonia nitrogen, and other side reactions may occur, so that the removal rate of the contaminants cannot be further increased.

In the electro-oxidation process, bivalent manganese ions are oxidized to generate tetravalent manganese, and the tetravalent manganese can be settled and separated from the wastewater in an alkaline environment. The ammonia nitrogen in the wastewater is oxidized to generate nitrogen and is separated from the wastewater.

Collecting the gas generated in the electrolysis process, firstly passing through an alkaline absorption tank to absorb the gas generated in the wastewater treatment process, and directly discharging the residual nitrogen.

And 3, discharging the wastewater after the electrooxidation treatment into a secondary sedimentation tank, and performing sedimentation separation to obtain the treated wastewater.

And discharging the wastewater after the electrooxidation treatment into a secondary sedimentation tank for sedimentation. In the electro-oxidation process, bivalent manganese ions in the wastewater are oxidized to generate tetravalent manganese, and the tetravalent manganese is separated from the wastewater in the form of manganese dioxide and manganese hydroxide. Thereby separating the manganese, and the separated manganese can be transferred to the manganese recovery process.

After settling separation, the pH value of the wastewater is reduced, and if the pH value of the wastewater is 6.5-8, the wastewater can be directly discharged, and if the pH value is less than 6.5, the pH value of the wastewater needs to be adjusted by using a pH adjusting agent, wherein the pH adjusting agent is as described in the step 1.

After the pH value is adjusted, the content of pollutants in the wastewater can reach the national discharge standard (the relevant discharge standard of industrial wastewater: GB23727-2020, GB8978), and the treatment process is completed.

According to the invention, the radioactive comprehensive wastewater containing high uranium, high manganese, ammonia nitrogen and COD is treated, the generation of radioactive waste residues is greatly reduced, the manganese, ammonia nitrogen and COD in the wastewater can be synchronously removed, the wastewater treatment is completed, and the discharge standard is reached. The process is simple, the equipment requirement is low, no additional treating agent is required, and batch treatment can be carried out.

Examples

Example 1

And (3) analyzing the waste water of a certain uranium tailing pond, wherein the uranium concentration is 8mg/L, the manganese ion concentration is 47.5mg/L, the inorganic ammonia nitrogen concentration is 378mg/L, the COD concentration is 210mg/L, and the chloride ion concentration is 1870 mg/L.

Introducing 2000mL of radioactive comprehensive wastewater into a uranium removal sedimentation tank, adding 11g of carbide slag with the average particle size of 1mm, stirring and reacting for 0.5h at room temperature, wherein the pH value is 10. Standing for 5h to precipitate the precipitate, and filtering to separate.

Introducing the separated wastewater into an electrolytic cell by adopting Ti/RuO₂-IrO₂The mesh titanium-based polar plate is used as an anode plate, the stainless steel plate is used as a cathode plate, the distance between the polar plates is 10cm, and the current density is adjusted to be 20mA/cm²And processing for 3 h.

And (3) introducing the treated wastewater into a secondary sedimentation tank, precipitating, and separating, wherein the pH value of the treated wastewater is tested to be 7. And testing the uranium content, the manganese ion content, the ammonia nitrogen content and the COD value of the wastewater to be discharged, wherein the test results are shown in Table 1.

Table 1:

example 2

The radioactive complex waste water was treated as in example 1, with the only difference that: 9g and 13g of carbide slag with the average particle size of 1mm are respectively added, and after stirring and reacting for 0.5h at room temperature, the pH values are respectively 9.5 and 11. And testing the pH value, uranium content, manganese ion content, ammonia nitrogen content and COD value of the wastewater to be discharged, wherein the test results are shown in Table 2.

Table 2:

example 3

Mine wastewater was treated as in example 1, except that: the current density is 15mA/cm². Testing the pH value, uranium content, manganese ion content, ammonia nitrogen content and COD value of the wastewater to be discharged, and the test results are shown in the table3, respectively.

Table 3:

example 4

Mine wastewater was treated as in example 1, except that: adding 8g of caustic soda flakes with the average particle size of 1mm, stirring and reacting for 0.5h at room temperature, wherein the pH value is 11; after the electrolysis treatment, the wastewater to be discharged with the pH value of 8 is obtained. And testing the uranium content, the manganese ion content, the ammonia nitrogen content and the COD value of the wastewater to be discharged, wherein the test results are shown in Table 4.

Table 4:

example 5

Mine wastewater was treated as in example 1, except that: adding 8g of caustic soda flakes with the average particle size of 1mm, stirring and reacting for 0.5h at room temperature, wherein the pH value is 11; during electrolysis, the adopted anode plate is Ti/RuO₂-IrO₂-SnO₂The current density of the reticular titanium-based polar plate is 20mA/cm²(ii) a After the electrolytic treatment, the test results are shown in Table 5. The pH value, manganese ion content, ammonia nitrogen content and COD value of the wastewater to be discharged were measured, and the test results are shown in table 5.

Table 5:

the present invention has been described in detail with reference to specific embodiments and/or illustrative examples, but the description is not intended to limit the invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, which fall within the scope of the present invention. The scope of the invention is defined by the appended claims.