Sodium nitrate wastewater treatment device for recovering selenium

Abstract

The utility model relates to the technical field of wastewater treatment, and particularly discloses a sodium nitrate wastewater treatment device for recovering selenium, which comprises a main storage tank, a nanofiltration membrane, a wastewater storage tank, a concentrated solution storage tank and a filter press, the main storage tank is used for storing selenium-containing sodium nitrate wastewater; a liquid outlet of the main storage tank is connected with the nanofiltration membrane; the nanofiltration membrane is used for filtering the selenium-containing sodium nitrate wastewater; the wastewater storage tank is connected with the permeation side of the nanofiltration membrane; the concentrated solution storage tank is connected with the interception side of the nanofiltration membrane; and the filter press is connected with the concentrated solution storage tank. According to the scheme, after the selenium-containing sodium nitrate wastewater stored in the main storage tank is filtered by the nanofiltration membrane, high-valence ions and low-valence ions can be separated, so that high-valence selenium ions are recycled, the utilization rate of selenium is increased, and the problem of selenium waste caused by direct discharge of the selenium-containing sodium nitrate wastewater is effectively solved.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment technology, and in particular to a sodium nitrate wastewater treatment device for selenium recovery. Background Technology

[0002] In the process of selenium purification, in order to remove impurities from the selenium raw material, a common method is to use sodium nitrate as an oxidant to mix with the selenium raw material, and then heat the mixture to produce an oxidation-reduction reaction. After heating, sodium nitrate oxidizes the impurities in the selenium raw material into compounds that are easier to separate. Then, through a separation process, sodium nitrate wastewater and purified selenium are obtained.

[0003] In existing selenium purification processes, the resulting sodium nitrate wastewater is generally discharged after treatment; however, this sodium nitrate wastewater still contains some selenium ions, thus resulting in a waste of selenium. Utility Model Content

[0004] In view of this, the purpose of this application is to provide a sodium nitrate wastewater treatment device for recovering selenium, which is used to recover selenium from selenium-containing sodium nitrate wastewater and solve the problem of selenium waste caused by the direct discharge of selenium-containing sodium nitrate wastewater.

[0005] To achieve the above-mentioned technical objectives, this application provides a sodium nitrate wastewater treatment device for selenium recovery, comprising: a main storage tank, a nanofiltration membrane, a wastewater storage tank, a concentrate storage tank, and a filter press;

[0006] The main storage tank is used to store selenium-containing sodium nitrate wastewater;

[0007] The outlet of the main storage tank is connected to the nanofiltration membrane;

[0008] The nanofiltration membrane is used to filter the selenium-containing sodium nitrate wastewater;

[0009] The wastewater storage tank is connected to the permeation side of the nanofiltration membrane;

[0010] The concentrate storage tank is connected to the filtration side of the nanofiltration membrane;

[0011] The filter press is connected to the concentrate storage tank.

[0012] Furthermore, it also includes: a mixing tank;

[0013] One end of the mixing tank is connected to the outlet of the main storage tank, and the other end is connected to the inlet of the nanofiltration membrane.

[0014] Furthermore, the mixing tank is equipped with a pH adjuster feeding port.

[0015] Furthermore, a pump body is provided between the main storage tank and the mixing tank;

[0016] The mixing tank is equipped with a first level gauge.

[0017] The first level gauge and the first pump body are electrically connected.

[0018] Furthermore, a second pump body is provided between the stirring tank and the nanofiltration membrane;

[0019] A second level gauge is installed inside the wastewater storage tank;

[0020] The second level gauge and the second pump body are electrically connected.

[0021] Furthermore, it also includes: reverse osmosis membranes;

[0022] The outlet of the wastewater storage tank is connected to the inlet of the reverse osmosis membrane.

[0023] Furthermore, it also includes: evaporator;

[0024] The evaporator is connected to the filtration side of the reverse osmosis membrane.

[0025] Furthermore, a third pump body is installed between the wastewater storage tank and the reverse osmosis membrane.

[0026] Furthermore, the concentrated liquid storage tank is equipped with a stirring paddle.

[0027] Furthermore, the concentrated liquid storage tank is equipped with a reducing agent feeding port.

[0028] As can be seen from the above technical solutions, this application provides a sodium nitrate wastewater treatment device for selenium recovery, comprising: a main storage tank, a nanofiltration membrane, a wastewater storage tank, a concentrate storage tank, and a filter press; the main storage tank is used to store selenium-containing sodium nitrate wastewater; the outlet of the main storage tank is connected to the nanofiltration membrane; the nanofiltration membrane is used to filter the selenium-containing sodium nitrate wastewater; the wastewater storage tank is connected to the permeate side of the nanofiltration membrane; the concentrate storage tank is connected to the retention side of the nanofiltration membrane; and the filter press is connected to the concentrate storage tank.

[0029] In this scheme, the selenium-containing sodium nitrate wastewater stored in the main storage tank can be separated into high-valence and low-valence ions after being filtered by a nanofiltration membrane, thereby realizing the recovery of high-valence selenium ions, improving the utilization rate of selenium, and effectively solving the problem of selenium waste caused by the direct discharge of selenium-containing sodium nitrate wastewater. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A schematic diagram of a sodium nitrate wastewater treatment device for selenium recovery provided in an embodiment of this application;

[0032] In the diagram: 10, Main storage tank; 20, Nanofiltration membrane; 30, Wastewater storage tank; 31, Second level gauge; 40, Concentrate storage tank; 50, Filter press; 60, Mixing tank; 61, pH adjuster feed port; 62, First level gauge; 70, Reverse osmosis membrane; 80, Evaporator; 91, Pump No. 1; 92, Pump No. 2; 93, Pump No. 3; 94, Pump No. 4. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments in this application specification, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection claimed in this application.

[0034] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0035] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a replaceable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0036] Please see Figure 1 The sodium nitrate wastewater treatment device for selenium recovery provided in this application embodiment includes: a main storage tank 10, a nanofiltration membrane 20, a wastewater storage tank 30, a concentrate storage tank 40, and a filter press 50.

[0037] The main storage tank 10 is used to store selenium-containing sodium nitrate wastewater. The outlet of the main storage tank 10 is connected to a nanofiltration membrane 20. The nanofiltration membrane 20 is used to filter the selenium-containing sodium nitrate wastewater.

[0038] The selenium-containing sodium nitrate wastewater generated after selenium purification contains sodium nitrate and sodium selenate; specifically, sodium ions, nitrate ions, and selenate ions are present in the solution. The retention performance of the nanofiltration membrane 20 is based on factors such as the size and charge of molecules or ions. It has a relatively high retention rate for divalent and multivalent ions, and a lower retention rate for monovalent ions. Because the nanofiltration membrane has a relatively low retention rate for monovalent ions, a large proportion of sodium ions in the solution will permeate through the nanofiltration membrane. Simultaneously, some nitrate ions will also permeate through the nanofiltration membrane 20 due to their smaller ionic radius and relatively lower valence state. Therefore, the permeate contains a relatively large number of sodium and nitrate ions; in addition, a small amount of selenate ions will also permeate through the nanofiltration membrane, but their concentration is usually lower than that of sodium and nitrate ions.

[0039] Nanofiltration membranes have a high rejection rate for divalent ions, so most selenate ions will remain in the retentate. To maintain the electroneutrality of the solution, a certain amount of sodium ions will also be retained to balance the charge; additionally, some nitrate ions will remain. Overall, the concentration of selenate in the retentate will be higher than that of nitrate.

[0040] Therefore, by using nanofiltration membrane 20, low-valent sodium nitrate solution and high-valent selenium ions in wastewater can be separated to obtain sodium selenate solution with higher purity.

[0041] In this embodiment, after the selenium-containing sodium nitrate wastewater passes through the nanofiltration membrane 20, the wastewater storage tank 30 is connected to the permeation side of the nanofiltration membrane 20; the concentrate storage tank 40 is connected to the retention side of the nanofiltration membrane 20; and the filter press 50 is connected to the concentrate storage tank 40.

[0042] Specifically, the permeate through the nanofiltration membrane 20 flows into the wastewater storage tank 30 through its permeate side. The retentate intercepted by the nanofiltration membrane 20 flows into the concentrate storage tank 40 through its retentate side. The concentrate storage tank 40 is used for the selenium recovery process. This selenium recovery process can be a conventional recovery process, such as adding a precipitating agent like barium salt to precipitate selenate ions; or, for example, electrolyzing selenate ions into monovalent selenium for recovery. After the recovery process, the wastewater is separated by filtration using a filter press 50.

[0043] In one embodiment, it further includes: a stirring tank 60; one end of the stirring tank 60 is connected to the outlet of the main storage tank 10, and the other end is connected to the inlet of the nanofiltration membrane 20.

[0044] Specifically, the mixing tank 60 is located between the main storage tank 10 and the nanofiltration membrane 20, which can agitate the wastewater, making the concentration of pollutants in the wastewater more uniform and ensuring the filtration effect of the nanofiltration membrane 20.

[0045] Furthermore, the mixing tank 60 is provided with a pH adjuster inlet 61. The pH adjuster inlet 61 is used for adding pH adjuster.

[0046] In this embodiment, the pH adjuster can be dilute nitric acid. Adding dilute nitric acid to the mixing tank 60 neutralizes the pH of the wastewater, preventing it from becoming too acidic. In practical applications, dilute nitric acid can be used to adjust the pH of the wastewater to 5-6.

[0047] In one embodiment, a No. 1 pump body 91 is provided between the main storage tank 10 and the stirring tank 60; a first level gauge 62 is provided inside the stirring tank 60; the first level gauge 62 and the No. 1 pump body 91 are electrically connected.

[0048] The liquid level in the mixing tank 60 can be automatically controlled by the first pump body 91 and the first level gauge 62. Specifically, when the first level gauge 62 detects that the liquid level in the mixing tank 60 is lower than the preset low level, the first pump body 91 starts to pump wastewater into the mixing tank 60. When the first level gauge 62 detects that the liquid level in the mixing tank 60 is higher than the preset high level, the first pump body 91 shuts down.

[0049] In one embodiment, a second pump body 92 is provided between the stirring tank 60 and the nanofiltration membrane 20; a second level gauge 31 is provided inside the wastewater storage tank 30; the second level gauge 31 and the second pump body 92 are electrically connected.

[0050] The second pump body 92 and the second level gauge 31 enable automated control of the liquid level in the wastewater storage tank 30. Specifically, when the second level gauge 31 detects that the liquid level in the wastewater storage tank 30 is lower than the preset low level, the second pump body 92 starts, pumping wastewater into the wastewater storage tank 30. When the second level gauge 31 detects that the liquid level in the wastewater storage tank 30 is higher than the preset high level, the second pump body 92 shuts down.

[0051] In one embodiment, it further includes: a reverse osmosis membrane 70; the outlet of the wastewater storage tank 30 is connected to the inlet of the reverse osmosis membrane 70.

[0052] As a further improvement, a third pump body 93 is installed between the wastewater storage tank 30 and the reverse osmosis membrane 70. The third pump body 93 is electrically connected to the second level gauge 31.

[0053] When the second level gauge 31 detects that the liquid level in the wastewater storage tank 30 is higher than the preset high level, the third pump 93 is activated, pumping the permeate into the reverse osmosis membrane 70 for filtration. After filtration, pure water and sodium nitrate solution are produced; the pure water and sodium nitrate are recycled separately.

[0054] In one embodiment, it further includes: an evaporator 80; the evaporator 80 is connected to the filtration side of the reverse osmosis membrane 70.

[0055] Evaporator 80 can evaporate sodium nitrate solution to form sodium nitrate solid for recovery.

[0056] In the application, a fourth pump 94 can be installed between the concentrate storage tank 40 and the filter press 50. After the selenium recovery process, the fourth pump 94 is activated to pump the solution into the filter press 50.

[0057] In one embodiment, a stirring paddle 41 is provided inside the concentrate storage tank 40. The stirring paddle 41 can stir the stagnant liquid inside the concentrate storage tank 40 to ensure the recovery effect of the selenium recovery process.

[0058] In one embodiment, the concentrate storage tank 40 is provided with a reducing agent inlet 42. A reducing agent can be added into the concentrate storage tank 40 through the reducing agent inlet 42 to achieve the reduction and recovery of selenium ions.

[0059] Specifically, the reducing agent can be, for example, hydrazine hydrate, which reduces hexavalent selenium ions to crude selenium.

[0060] The sodium nitrate wastewater treatment device for selenium recovery provided in this application embodiment can separate low-priced sodium nitrate solution and high-priced sodium selenate solution through nanofiltration membrane. Then, the sodium nitrate solution is evaporated into sodium nitrate salt product for recycling, while selenium ions are reduced into crude selenium product for recycling.

[0061] The above are merely preferred embodiments of this application and are not intended to limit the present invention. Although the present application has been described in detail with reference to examples, those skilled in the art can still modify the technical solutions described in the foregoing examples or make equivalent substitutions for some of the technical features. However, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A sodium nitrate wastewater treatment device for selenium recovery, characterized in that, include: Main storage tank (10), nanofiltration membrane (20), wastewater storage tank (30), concentrate storage tank (40) and filter press (50); The main storage tank (10) is used to store selenium-containing sodium nitrate wastewater; The outlet of the main storage tank (10) is connected to the nanofiltration membrane (20). The nanofiltration membrane (20) is used to filter the selenium-containing sodium nitrate wastewater; The wastewater storage tank (30) is connected to the permeation side of the nanofiltration membrane (20); The concentrate storage tank (40) is connected to the filtration side of the nanofiltration membrane (20), and the concentrate storage tank (40) is used for the selenium recovery process. The filter press (50) is connected to the concentrate storage tank (40).

2. The sodium nitrate wastewater treatment device for selenium recovery according to claim 1, characterized in that, Also includes: Mixing tank (60); One end of the stirring tank (60) is connected to the outlet of the main storage tank (10), and the other end is connected to the inlet of the nanofiltration membrane (20).

3. The sodium nitrate wastewater treatment device for selenium recovery according to claim 2, characterized in that, The mixing tank (60) is provided with a pH adjuster feeding port (61).

4. The sodium nitrate wastewater treatment device for selenium recovery according to claim 2, characterized in that, A pump body (91) is provided between the main storage tank (10) and the mixing tank (60). The mixing tank (60) is equipped with a first level gauge (62); The first level gauge (62) and the first pump body (91) are electrically connected.

5. The sodium nitrate wastewater treatment device for selenium recovery according to claim 2 or 4, characterized in that, A second pump body (92) is provided between the stirring tank (60) and the nanofiltration membrane (20). The wastewater storage tank (30) is equipped with a second level gauge (31); The second level gauge (31) and the second pump body (92) are electrically connected.

6. The sodium nitrate wastewater treatment device for selenium recovery according to claim 1, characterized in that, Also includes: Reverse osmosis membrane (70); The outlet of the wastewater storage tank (30) is connected to the inlet of the reverse osmosis membrane (70).

7. The sodium nitrate wastewater treatment device for selenium recovery according to claim 6, characterized in that, Also includes: Evaporator (80); The evaporator (80) is connected to the filtration side of the reverse osmosis membrane (70).

8. The sodium nitrate wastewater treatment device for selenium recovery according to claim 6, characterized in that, A third pump body (93) is installed between the wastewater storage tank (30) and the reverse osmosis membrane (70).

9. The sodium nitrate wastewater treatment device for selenium recovery according to claim 1, characterized in that, The concentrated liquid storage tank (40) is equipped with a stirring paddle (41).

10. The sodium nitrate wastewater treatment device for selenium recovery according to claim 1, characterized in that, The concentrated liquid storage tank (40) is equipped with a reducing agent feeding port (42).

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