Waste acid recovery method of nanofiltration membrane separation technology

Abstract

The invention discloses a waste acid recovery method of a nanofiltration membrane separation technology, which belongs to the technical field of waste acid treatment, recovery and reutilization, and specifically comprises a nanofiltration membrane group, a primary acid recovery pipeline, a secondary acid recovery pipeline and a residual acid recovery pipeline, the nanofiltration membrane group comprises a waste acid conveying pipeline, a plurality of primary membrane pipes and a plurality of secondary membrane pipes; according to the invention, a manner of treating the wastewater by adopting the nanofiltration membrane group is adopted to replace a manner of treating the wastewater by adopting a traditional diffusion dialysis method, so that the treatment capacity of waste acid is improved, the recovery rate of the waste acid is improved, and the difficulty of secondary wastewater treatment is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of waste acid treatment, recovery and reuse, and specifically relates to a waste acid recovery method using a nanofiltration membrane separation technology. Background Art

[0002] At present, a better treatment method for the corrosion waste acid in the aluminum foil industry is to use diffusion dialysis to recover the free acid in it. This method has been reported both at home and abroad and has been successfully commercialized. Diffusion dialysis is a membrane separation process driven by concentration difference. When the waste acid and pure water (as the receiving liquid of the free acid) are injected into the diffusion dialyzer, the anions and protons in the waste acid can pass through the anion exchange membrane driven by the concentration difference to reach the receiving liquid. In this way, a free acid that has received a large amount of anions and protons and a waste salt solution that has lost a large amount of free acid is obtained at the outlet of the diffusion dialyzer. Diffusion dialysis technology has the characteristics of high efficiency and low operating cost, and is very economically attractive.

[0003] However, the treatment of waste acid by diffusion dialysis has the following shortcomings: 1. The amount of waste acid treated is small; 2. The volume of recovered waste acid is large and cannot be completely reused in the production line; 3. The secondary wastewater generated is difficult to treat. Therefore, it is necessary to provide a waste acid recovery method using nanofiltration membrane separation technology to solve the above technical problems. Summary of the invention

[0004] To solve the problems raised in the above background technology, the present invention provides a waste acid recovery method using nanofiltration membrane separation technology, which has the characteristics of large waste acid treatment capacity, high recovery rate of waste acid solution, and low difficulty in secondary wastewater treatment.

[0005] To achieve the above object, the present invention provides the following technical solutions: a waste acid recovery method of nanofiltration membrane separation technology, comprising a nanofiltration membrane group, a primary acid recovery pipeline, a secondary acid recovery pipeline and a residual acid recovery pipeline; The nanofiltration membrane group includes a waste acid conveying pipeline, multiple primary membrane tubes and multiple secondary membrane tubes. The liquid outlet end of the waste acid conveying pipeline is connected to the liquid inlet ends of the multiple primary membrane tubes, the first liquid outlet ends of the multiple primary membrane tubes are connected to the liquid inlet ends of the multiple secondary membrane tubes, the second liquid outlet ends of the multiple primary membrane tubes are connected to the liquid inlet end of the primary acid recovery pipeline, the first liquid outlet ends of the multiple secondary membrane tubes are connected to the liquid inlet end of the secondary acid recovery pipeline, and the second liquid outlet ends of the multiple second-stage membrane tubes are connected to the liquid inlet end of the residual acid recovery pipeline.

[0006] Preferably, it also includes a waste acid pretreatment device, a waste acid storage tank and a pressure pump, the liquid inlet end of the waste acid treatment device is connected to the waste acid liquid inlet pipeline, the liquid outlet end of the waste acid treatment device is connected to the liquid inlet end of the waste acid storage tank, the liquid outlet end of the waste acid storage tank is connected to the liquid inlet end of the pressure pump, and the liquid outlet end of the pressure pump is connected to the liquid inlet end of the waste acid delivery pipeline.

[0007] Preferably, at least two groups of the primary membrane tubes and the secondary membrane tubes are provided.

[0008] Preferably, the waste acid pretreatment device adopts a membrane filter.

[0009] Preferably, the booster pump is a high-pressure plunger pump, and the high-pressure plunger pump is used to increase the pressure of the waste acid solution to 3.0-5.0 MPa.

[0010] Preferably, the primary acid recovery pipeline, the secondary acid recovery pipeline, the residual acid recovery pipeline and the waste acid transportation pipeline are all made of acid-resistant alloy pipelines.

[0011] Preferably, a waste acid recovery method using nanofiltration membrane separation technology: S1: Start the waste acid solution injection device, inject the waste acid solution into the waste acid preprocessor through the waste acid inlet pipe, so that the waste acid preprocessor can filter the fine solid particles and a small amount of oil in the waste acid solution; S2: The pretreated waste acid solution enters the waste acid storage tank to store the pretreated waste acid solution; S3: The waste acid solution in the waste acid storage tank enters the pressure pump, so that the pressure pump increases the pressure of the waste acid solution to 3.0-5.0MPa; S4: the pressurized waste acid solution enters into a plurality of primary membrane tubes through a waste acid delivery pipeline, so that the plurality of primary membrane tubes perform dialysis separation on the waste acid solution, and then the dialysis-separated waste acid solution enters into a plurality of secondary membrane tubes, so that the plurality of secondary membrane tubes further perform dialysis separation on the waste acid solution; S5: After the waste acid solution is initially dialyzed and separated in the primary membrane tube, the primary acid recovery pipeline collects the acid solution discharged from the second liquid outlet of the primary membrane tube, and the metal cation concentration in the acid solution collected in the primary acid recovery pipeline meets the standard and can be directly reused; S6: After the waste acid discharged from the first liquid outlet of the primary membrane tube is dialyzed and separated again in the secondary membrane tube, the secondary acid recovery pipeline collects the acid solution discharged from the second liquid outlet of the secondary membrane tube; S7: The acid solution with too high concentration in the secondary acid recovery pipeline re-enters the waste acid storage tank through the reflux pipeline, and the mixed acid solution enters the primary membrane tube and the secondary membrane tube after being pressurized by the pressure pump, and the primary membrane tube and the secondary membrane tube perform dialysis separation on the acid solution again, so as to achieve more accurate concentration control, reduce the fluctuation range of metal cation concentration in the recovered acid, and improve the operation efficiency of the nanofiltration dialysis system; S8: The acid solution with a slightly lower concentration in the residual acid recovery pipeline re-enters the liquid inlet end of the booster pump through the reflux pipeline. The mixed acid solution enters the first-level membrane tube and the second-level membrane tube after being pressurized by the booster pump, so that the first-level membrane tube and the second-level membrane tube perform dialysis separation on the mixed acid solution again.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention adopts a nanofiltration membrane group to treat wastewater, replacing the traditional diffusion dialysis method for treating wastewater, thereby increasing the treatment capacity of waste acid, improving the recovery rate of waste acid, and reducing the difficulty of secondary wastewater treatment.

[0013] 2. The present invention can collect the acid solution discharged from the first liquid outlet after the dialysis separation of the secondary membrane tube by setting up a secondary acid recovery pipeline, and re-enter the waste acid storage tank through the reflux pipeline with the acid solution with too high concentration after collection. The mixed acid solution enters the first membrane tube and the second membrane tube after being pressurized by the pressure pump, and the first membrane tube and the second membrane tube perform dialysis separation on the acid solution again, so as to achieve more accurate concentration control, reduce the fluctuation range of the metal cation concentration in the recovered acid, and improve the operation efficiency of the nanofiltration dialysis system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 It is a schematic diagram of the structure of the present invention; In the figure: 1. Primary acid recovery pipeline; 2. Secondary acid recovery pipeline; 3. Residual acid recovery pipeline; 4. Waste acid transportation pipeline; 5. Primary membrane tube; 6. Secondary membrane tube; 7. Waste acid pretreatment unit; 8. Waste acid inlet pipeline; 9. Waste acid storage tank; 10. Pressure pump. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0016] See also Figure 1 The present embodiment provides the following technical solutions: a waste acid recovery method using nanofiltration membrane separation technology, comprising a waste acid pretreatment device 7, a waste acid storage tank 9 and a pressure pump 10, wherein the liquid inlet end of the waste acid treatment device is connected to a waste acid liquid inlet pipeline 8, the liquid outlet end of the waste acid treatment device is connected to the liquid inlet end of the waste acid storage tank 9, the liquid outlet end of the waste acid storage tank 9 is connected to the liquid inlet end of the pressure pump 10, and the liquid outlet end of the pressure pump 10 is connected to the liquid inlet end of the waste acid delivery pipeline 4.

[0017] It includes a nanofiltration membrane group, a primary acid recovery pipeline 1, a secondary acid recovery pipeline 2 and a residual acid recovery pipeline 3; the nanofiltration membrane group includes a waste acid conveying pipeline 4, multiple primary membrane tubes 5 and multiple secondary membrane tubes 6, the liquid outlet end of the waste acid conveying pipeline 4 is connected to the liquid inlet ends of the multiple primary membrane tubes 5, and the first liquid outlet ends of the multiple primary membrane tubes 5 are connected to the liquid inlet ends of the multiple secondary membrane tubes 6. In some embodiments, at least two groups of primary membrane tubes 5 and secondary membrane tubes 6 are arranged. With the cooperation of the primary membrane tubes 5 and the secondary membrane tubes 6, the waste acid solution can be dialyzed and separated. By adopting the nanofiltration membrane group to treat wastewater, the traditional diffusion dialysis method for treating wastewater is replaced, the treatment capacity of waste acid is increased, the recovery rate of waste acid is increased, and the difficulty of secondary wastewater treatment is reduced.

[0018] The second liquid outlet ends of the plurality of primary membrane tubes 5 are connected to the liquid inlet end of the primary acid recovery pipeline 1. In some embodiments, the primary acid recovery pipeline 1 collects the acid solution discharged from the second liquid outlet ends of the primary membrane tubes 5, and the acid solution collected in the primary acid recovery pipeline 1 can be directly reused if the metal cation concentration meets the standard.

[0019] The first liquid outlet ends of the plurality of secondary membrane tubes 6 are connected to the liquid inlet end of the secondary acid recovery pipeline 2. In some embodiments, the acid solution with excessively high concentration in the secondary acid recovery pipeline 2 re-enters the waste acid storage tank 9 through the reflux pipeline, and the mixed acid solution enters the first membrane tube 5 and the second membrane tube 6 after being pressurized by the pressure pump 10, so that the first membrane tube 5 and the second membrane tube 6 perform dialysis separation on the acid solution again, thereby achieving more precise concentration control, reducing the fluctuation range of the metal cation concentration in the recovered acid, and improving the operating efficiency of the nanofiltration dialysis system.

[0020] The second liquid outlet ends of the plurality of second-stage membrane tubes 6 are connected to the liquid inlet end of the residual acid recovery pipeline 3. In some embodiments, the acid solution with a slightly lower concentration in the residual acid recovery pipeline 3 re-enters the liquid inlet end of the booster pump 10 through the reflux pipeline, and the mixed acid solution enters the first-stage membrane tube 5 and the second-stage membrane tube 6 after being pressurized by the booster pump 10, so that the first-stage membrane tube 5 and the second-stage membrane tube 6 re-dialyze and separate the mixed acid solution.

[0021] In some embodiments, the waste acid pretreatment device 7 uses a membrane filter, which can filter fine solid particles and a small amount of oil in the waste acid solution to prevent clogging of the nanofiltration membrane group and affect the acid flow rate of the nanofiltration membrane group.

[0022] In some embodiments, the booster pump 10 uses a high-pressure plunger pump, which is used to increase the pressure of the waste acid solution to 3.0-5.0 MPa. After the pressure of the waste acid solution is increased, the waste acid reaction efficiency can be improved, the recovery of the waste acid can be promoted, and the emission of pollutants can be reduced.

[0023] In some embodiments, the primary acid recovery pipeline 1, the secondary acid recovery pipeline 2, the residual acid recovery pipeline 3 and the waste acid transport pipeline 4 are all made of acid-resistant alloy pipelines.

[0024] The waste acid recovery method of nanofiltration membrane separation technology comprises the following steps: S1: Start the waste acid solution injection device, inject the waste acid solution into the waste acid pretreatment device 7 through the waste acid inlet pipe 8, so that the waste acid pretreatment device 7 filters the fine solid particles and a small amount of oil in the waste acid solution; S2: the pretreated waste acid solution enters the waste acid storage tank 9 to store the pretreated waste acid solution; S3: The waste acid solution in the waste acid storage tank 9 enters the pressure pump 10, so that the pressure pump 10 increases the pressure of the waste acid solution to 3.0-5.0 MPa; S4: the pressurized waste acid solution enters into the multiple primary membrane tubes 5 through the waste acid delivery pipe 4, so that the multiple primary membrane tubes 5 perform dialysis separation on the waste acid solution, and then the waste acid solution after dialysis separation enters into the multiple secondary membrane tubes 6, so that the multiple secondary membrane tubes 6 further perform dialysis separation on the waste acid solution; S5: After the waste acid solution is initially dialyzed and separated in the primary membrane tube 5, the primary acid recovery pipeline 1 collects the acid solution discharged from the second liquid outlet of the primary membrane tube 5, and the metal cation concentration in the acid solution collected in the primary acid recovery pipeline 1 meets the standard and can be directly reused; S6: After the waste acid discharged from the first liquid outlet of the primary membrane tube 5 is dialyzed and separated again in the secondary membrane tube 6, the secondary acid recovery pipeline 2 collects the acid solution discharged from the second liquid outlet of the secondary membrane tube 6; S7: The acid solution with too high concentration in the secondary acid recovery pipeline 2 re-enters the waste acid storage tank 9 through the reflux pipeline, and the mixed acid solution enters the primary membrane tube 5 and the secondary membrane tube 6 after being pressurized by the pressure pump 10, and the primary membrane tube 5 and the secondary membrane tube 6 are again used to perform dialysis separation on the acid solution, so as to achieve more accurate concentration control, reduce the fluctuation range of the metal cation concentration in the recovered acid, and improve the operation efficiency of the nanofiltration dialysis system; S8: The acid solution with a slightly lower concentration in the residual acid recovery pipeline 3 re-enters the liquid inlet end of the booster pump 10 through the reflux pipeline, and the mixed acid solution enters the first-level membrane tube 5 and the second-level membrane tube 6 after being pressurized by the booster pump 10, so that the first-level membrane tube 5 and the second-level membrane tube 6 re-dialyze and separate the mixed acid solution.

[0025] The working principle of the present invention is as follows: the waste acid solution injection device is started, and the waste acid solution is injected into the waste acid preprocessor 7 through the waste acid inlet pipe 8, so that the waste acid preprocessor 7 filters the fine solid particles and a small amount of oil in the waste acid solution; the pretreated waste acid solution enters the waste acid storage tank 9, and the pretreated waste acid solution is stored; The waste acid solution in the waste acid storage tank 9 enters the pressure pump 10, so that the pressure pump 10 increases the pressure of the waste acid solution to 3.0-5.0 MPa; the pressurized waste acid solution enters into the multiple primary membrane tubes 5 through the waste acid delivery pipeline 4, respectively, so that the multiple primary membrane tubes 5 perform dialysis separation on the waste acid solution, and then the dialysis-separated waste acid solution enters into the multiple secondary membrane tubes 6, so that the multiple secondary membrane tubes 6 further perform dialysis separation on the waste acid solution; After the waste acid solution is initially dialyzed and separated in the primary membrane tube 5, the primary acid recovery pipeline 1 collects the acid solution discharged from the second liquid outlet of the primary membrane tube 5, and the metal cation concentration in the acid solution collected in the primary acid recovery pipeline 1 meets the standard and can be directly reused; After the waste acid discharged from the first liquid outlet of the primary membrane tube 5 is dialyzed and separated again in the secondary membrane tube 6, the secondary acid recovery pipeline 2 collects the acid solution discharged from the second liquid outlet of the secondary membrane tube 6; The acid solution with too high concentration in the secondary acid recovery pipeline 2 re-enters the waste acid storage tank 9 through the reflux pipeline, and the mixed acid solution enters the primary membrane tube 5 and the secondary membrane tube 6 after being pressurized by the pressure pump 10, and the primary membrane tube 5 and the secondary membrane tube 6 are again used to perform dialysis separation on the acid solution, so as to achieve more accurate concentration control, reduce the fluctuation range of the metal cation concentration in the recovered acid, and improve the operation efficiency of the nanofiltration dialysis system; The acid solution with a slightly lower concentration in the residual acid recovery pipe 3 re-enters the liquid inlet end of the booster pump 10 through the reflux pipe, and the mixed acid solution enters the first membrane tube 5 and the second membrane tube 6 after being pressurized by the booster pump 10, so that the first membrane tube 5 and the second membrane tube 6 re-dialyze and separate the mixed acid solution.

[0026] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A waste acid recovery device using nanofiltration membrane separation technology, characterized in that: It includes a nanofiltration membrane group, a primary acid recovery pipeline (1), a secondary acid recovery pipeline (2) and a residual acid recovery pipeline (3); The nanofiltration membrane group comprises a waste acid conveying pipeline (4), a plurality of primary membrane tubes (5) and a plurality of secondary membrane tubes (6); the liquid outlet end of the waste acid conveying pipeline (4) is connected to the liquid inlet ends of the plurality of primary membrane tubes (5); the first liquid outlet ends of the plurality of primary membrane tubes (5) are connected to the liquid inlet ends of the plurality of secondary membrane tubes (6); the second liquid outlet ends of the plurality of primary membrane tubes (5) are connected to the liquid inlet end of the primary acid recovery pipeline (1); the first liquid outlet ends of the plurality of secondary membrane tubes (6) are connected to the liquid inlet end of the secondary acid recovery pipeline (2); and the second liquid outlet ends of the plurality of second-stage membrane tubes (6) are connected to the liquid inlet end of the residual acid recovery pipeline (3).

2. The waste acid recovery device of the nanofiltration membrane separation technology according to claim 1 is characterized in that: The invention also comprises a waste acid pretreatment device (7), a waste acid storage tank (9) and a pressure pump (10); the liquid inlet end of the waste acid treatment device is connected to a waste acid liquid inlet pipeline (8); the liquid outlet end of the waste acid treatment device is connected to the liquid inlet end of the waste acid storage tank (9); the liquid outlet end of the waste acid storage tank (9) is connected to the liquid inlet end of the pressure pump (10); and the liquid outlet end of the pressure pump (10) is connected to the liquid inlet end of the waste acid delivery pipeline (4).

3. The waste acid recovery device of the nanofiltration membrane separation technology according to claim 1 is characterized in that: At least two groups of the first-level membrane tubes (5) and the second-level membrane tubes (6) are provided.

4. The waste acid recovery device of the nanofiltration membrane separation technology according to claim 1 is characterized in that: The waste acid pretreatment device (7) adopts a membrane filter.

5. The waste acid recovery device of the nanofiltration membrane separation technology according to claim 1 is characterized in that: The booster pump (10) is a high-pressure plunger pump, which is used to increase the pressure of the waste acid solution to 3.0-5.0 MPa.

6. The waste acid recovery device of the nanofiltration membrane separation technology according to claim 1 is characterized in that: The primary acid recovery pipeline (1), the secondary acid recovery pipeline (2), the residual acid recovery pipeline (3) and the waste acid transport pipeline (4) are all made of acid-resistant alloy pipelines.

7. A method for recovering waste acid using nanofiltration membrane separation technology according to any one of claims 1 to 6, characterized in that: S1: starting the waste acid solution injection device to inject the waste acid solution into the waste acid pretreatment device (7) through the waste acid liquid inlet pipeline (8), so that the waste acid pretreatment device (7) filters the fine solid particles and a small amount of oil in the waste acid solution; S2: the pretreated waste acid solution enters the waste acid storage tank (9) to store the pretreated waste acid solution; S3: the waste acid solution in the waste acid storage tank (9) enters the pressure pump (10), so that the pressure pump (10) increases the pressure of the waste acid solution to 3.0-5.0 MPa; S4: the pressurized waste acid solution enters into the multiple primary membrane tubes (5) through the waste acid transport pipeline (4), so that the multiple primary membrane tubes (5) perform dialysis separation on the waste acid solution, and then the waste acid solution after dialysis separation enters into the multiple secondary membrane tubes (6), so that the multiple secondary membrane tubes (6) further perform dialysis separation on the waste acid solution; S5: After the waste acid solution is initially dialyzed and separated in the primary membrane tube (5), the primary acid recovery pipeline (1) collects the acid solution discharged from the second liquid outlet end of the primary membrane tube (5), and the metal cation concentration in the acid solution collected in the primary acid recovery pipeline (1) meets the standard and can be directly reused; S6: After the waste acid discharged from the first liquid outlet of the primary membrane tube (5) is dialyzed and separated again in the secondary membrane tube (6), the acid solution discharged from the second liquid outlet of the secondary membrane tube (6) is collected by the secondary acid recovery pipeline (2); S7: the acid solution with excessively high concentration in the secondary acid recovery pipeline (2) re-enters the waste acid storage tank (9) through the reflux pipeline, and the mixed acid solution is pressurized by the pressure pump (10) and enters the first membrane tube (5) and the second membrane tube (6), and the first membrane tube (5) and the second membrane tube (6) are again used to perform dialysis separation on the acid solution, thereby achieving more accurate concentration control, reducing the fluctuation range of the metal cation concentration in the recovered acid, and improving the operation efficiency of the nanofiltration dialysis system; S8: The acid solution with a slightly lower concentration in the residual acid recovery pipeline (3) re-enters the liquid inlet end of the booster pump (10) through the reflux pipeline. The mixed acid solution is pressurized by the booster pump (10) and enters the first membrane tube (5) and the second membrane tube (6), so that the first membrane tube (5) and the second membrane tube (6) re-dialyze and separate the mixed acid solution.

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