Electrochemical treatment method and application of fluorine-containing wastewater

Abstract

The invention belongs to the technical field of wastewater treatment, and discloses an electrochemical treatment method and application of fluorine-containing wastewater, and the electrochemical treatment method comprises the following steps: the fluorine-containing wastewater enters an electrochemical reactor, and an electric flocculation reaction is carried out by taking a soluble metal electrode as an anode and a dimensionally stable electrode as a cathode to remove fluorine ions in the wastewater; carrying out electrooxidation reaction by taking a dimensionally stable electrode as an anode and a soluble metal electrode as a cathode, and removing refractory organic matters in the wastewater; finally, the wastewater subjected to electrooxidation treatment enters a filtering device, and is discharged after being filtered. The method disclosed by the invention is simple and convenient in operation steps, small in occupied area and suitable for treating the refractory organic matters in the fluorine-containing wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and more specifically, to an electrochemical treatment method for fluorine-containing wastewater and its application. Background Art

[0002] Electrochemical wastewater treatment technology refers to the process of applying an external electric field to the system to make the charges move in a directional manner in the electric field, thereby using specific physical and chemical reactions to remove toxic and harmful pollutants in the system, including electroflocculation, electroflotation, electrodialysis, and electrochemical oxidation. Among them, electrochemical oxidation is often used to treat difficult-to-biodegrade organic matter in industrial wastewater, and has the advantages of high organic matter removal efficiency, non-selective removal, and no secondary pollution.

[0003] Industrially, wastewater discharged from fluorine-containing ore mining, metal smelting, aluminum processing, coke, electroplating and other industries often contains high concentrations of fluoride ions. Fluoride ions corrode the anode in electrocatalytic oxidation, seriously affecting the service life of the anode. Therefore, it is necessary to reduce the fluoride ion content in the water to meet the water inlet requirements of electrochemical oxidation treatment. Commonly used fluoride removal methods are generally precipitation and adsorption. The precipitation method has limited treatment effect and requires the addition of a large amount of reagents; the adsorbent in the adsorption method needs to be regenerated, and the investment cost is relatively high. Therefore, it is necessary to develop a new technology for the treatment of difficult-to-degrade organic matter in fluoride-containing wastewater. Summary of the invention

[0004] The purpose of the present invention is to provide an electrochemical treatment method for fluorine-containing wastewater and its application. The method has simple operation steps, occupies a small area, and is suitable for treating refractory organic matter in fluorine-containing wastewater.

[0005] In order to achieve the above-mentioned purpose, one aspect of the present invention provides an electrochemical treatment method for fluorine-containing wastewater, which comprises: the fluorine-containing wastewater enters an electrochemical reactor, and an electrocoagulation reaction is carried out with a soluble metal electrode as an anode and a shape-stable electrode as a cathode to remove fluoride ions in the wastewater; then the electrodes are reversed, and an electro-oxidation reaction is carried out with the shape-stable electrode as an anode and the soluble metal electrode as a cathode to remove difficult-to-degrade organic matter in the wastewater; finally, the wastewater after the electro-oxidation treatment enters a filtration device and is discharged after filtration.

[0006] Another aspect of the present invention provides application of the electrochemical treatment method in treating fluoride-containing wastewater.

[0007] The technical solution of the present invention has the following beneficial effects:

[0008] In the present invention, the electrocoagulation and electrochemical oxidation are arranged in the same electrochemical reactor, and the cathode and anode conversion of the electrode plate is realized by converting the positive and negative electrodes of the power supply. When the soluble metal electrode is used as the anode, the electrocoagulation occurs to remove the fluoride ions in the water. When the fluoride ion concentration reaches the electrochemical oxidation water inlet requirement, the shape-stable electrode is used as the anode to treat the refractory organic matter in the wastewater. The reversal treatment of the two electrodes can prevent the occurrence of electrode passivation.

[0009] The equipment of the present invention has simple process, easy operation, low energy consumption, no need to add reagents during the treatment process, low sludge production, no secondary pollution, and can achieve green and efficient treatment of difficult-to-degrade organic matter in fluoride-containing wastewater.

[0010] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0011] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0012] One aspect of the present invention provides an electrochemical treatment method for fluorine-containing wastewater, which comprises: the fluorine-containing wastewater enters an electrochemical reactor, and an electrocoagulation reaction is carried out with a soluble metal electrode as an anode and a shape-stable electrode as a cathode to remove fluoride ions in the wastewater; then the electrodes are reversed, and an electro-oxidation reaction is carried out with the shape-stable electrode as an anode and the soluble metal electrode as a cathode to remove difficult-to-degrade organic matter in the wastewater; finally, the wastewater after the electro-oxidation treatment enters a filtration device and is discharged after filtration.

[0013] In the present invention, electrochemical flocculation and electrochemical oxidation treatment are carried out in the same electrochemical reactor, the operation steps are simple and the occupied area is small.

[0014] In the present invention, the polarity reversal is achieved by switching the positive and negative poles of the power supply, that is, the positive and negative poles of the electrode plate are switched. The switching of the positive and negative poles of the power supply can be achieved manually, or the automatic switching of the positive and negative poles of the power supply can be set.

[0015] According to the present invention, preferably, when the fluoride ion concentration in the wastewater after electrocoagulation treatment reaches the electrochemical oxidation water inlet requirement, the electrode reversal is performed; preferably, when the fluoride ion concentration in the wastewater after electrocoagulation treatment is below 5 mg / L, the electrode reversal is performed.

[0016] According to the present invention, preferably, the soluble metal electrode is an aluminum electrode, an iron electrode or an aluminum-iron alloy electrode.

[0017] According to the present invention, preferably, the shape-stable electrode is a titanium-based metal-coated oxide electrode or a boron-doped diamond film electrode;

[0018] The metal coating oxide is preferably one or more of oxides of ruthenium, iridium, titanium, rhodium, tin, antimony, platinum and lead.

[0019] According to the present invention, preferably, the anode and cathode in the electrochemical reactor are one or more groups;

[0020] When there are multiple groups of anodes and cathodes, the anodes and cathodes are arranged crosswise.

[0021] According to the present invention, preferably, the distance between the anode and cathode plates is 0.5-3.0 cm.

[0022] In the present invention, preferably, when the anode and cathode are in multiple groups, the distance between two adjacent electrode plates is 0.5-3.0 cm.

[0023] According to the present invention, preferably, the current density of the electrochemical reactor is 20-50 mA / cm 2 .

[0024] According to the present invention, preferably, the time of the electrocoagulation reaction and the electrochemical oxidation reaction are independently 10-30 minutes.

[0025] In the present invention, the time of the electro-flocculation reaction and the electrochemical oxidation reaction is adjusted according to the fluoride ion content and the organic matter content in the wastewater.

[0026] According to the present invention, preferably, the fluorine content in the fluorine-containing wastewater is 10-50 mg / L.

[0027] Another aspect of the present invention provides application of the electrochemical treatment method in treating fluoride-containing wastewater.

[0028] The present invention will be described in detail below through examples.

[0029] The water quality of fluoride-containing wastewater is shown in Table 1.

[0030] Table 1

[0031] Wastewater <![CDATA[Ca 2+ ]]> Total Alkalinity <![CDATA[Cl - ]]> <![CDATA[SO4 2- ]]> pH Conductivity <![CDATA[F - ]]> COD 1 1303.2 133.4 6702.4 1632.1 7.6 23.16 21.8 106 2 2310.2 138.7 10905.6 1921.3 7.2 35.56 45.7 120

[0032] Note: pH has no unit, conductivity unit is ms / cm, other units are mg / L, Ca 2+ , total alkalinity are all calculated as CaCO3, the same below. 2+ Represents calcium hardness, the same below. The determination methods of each parameter are as follows: Ca 2+ : Reference standard GB / T 6910-2006; Total alkalinity: Reference standard GB / T 15451-2006; Cl - : Reference standard GB / T 15453-2008; SO42- : Reference standard GB / T14642-2009; pH value: Reference standard GB / T 6920-1986; Conductivity: Reference standard GB / T 6908-2008; F - : Reference standard GB / T 7484-1987; COD: Reference standard GB 11914-89.

[0033] In the following embodiments, the electrochemical reactor used is provided with a cathode plate and an anode plate.

[0034] In the following embodiments, F - The concentration of is tested according to the standard GB / T 7484-1987; the concentration of COD is tested according to the standard GB 11914-89.

[0035] Example 1

[0036] It is used for electrochemical treatment of refractory organic matter in fluoride-containing wastewater. The method is as follows: 1L fluoride-containing wastewater 1 first enters the electrochemical reactor, turns on the power, uses the aluminum electrode as the anode and the titanium-based lead dioxide electrode as the cathode to perform an electrocoagulation reaction to remove fluoride ions in the wastewater. The distance between the anode and cathode plates is 0.5 cm, and the plate areas of the anode and cathode are both 100 cm 2 , current density is 30mA / cm 2 The reaction time is 10 minutes. At this time, the fluoride ion concentration in the wastewater is below 5 mg / L. Then the poles are reversed. At this time, the titanium-based lead dioxide electrode is used as the anode and the aluminum electrode is used as the cathode for electro-oxidation reaction to remove the difficult-to-degrade organic matter in the wastewater. After 20 minutes of reaction, it enters the filtration device and is discharged after filtration. The fluoride ion and COD results of the effluent are listed in Table 2.

[0037] Example 2

[0038] It is used for electrochemical treatment of refractory organic matter in fluoride-containing wastewater. The method is as follows: 1L of fluoride-containing wastewater 1 first enters the electrochemical reactor, turns on the power, uses the iron electrode as the anode, and the titanium-based ruthenium iridium titanium oxide coating electrode as the cathode to perform an electrocoagulation reaction to remove fluoride ions in the wastewater. The distance between the anode and cathode plates is 1.0 cm, and the plate areas of the anode and cathode are both 100 cm 2 , current density is 40mA / cm 2 The reaction time is 15 minutes. At this time, the fluoride ion concentration in the wastewater is below 5 mg / L. Then the electrodes are reversed. At this time, the titanium-based ruthenium iridium titanium oxide coated electrode serves as the anode and the iron electrode serves as the cathode for electro-oxidation reaction to remove the difficult-to-degrade organic matter in the wastewater. After 30 minutes of reaction, it enters the filtration device and is discharged after filtration. The fluoride ion and COD results of the effluent are listed in Table 2.

[0039] Example 3

[0040] It is used for electrochemical treatment of refractory organic matter in fluoride-containing wastewater. The method is as follows: 1L fluoride-containing wastewater 1 first enters the electrochemical reactor, turns on the power, uses the aluminum-iron alloy electrode as the anode, and the titanium-based tin antimony oxide coating electrode as the cathode to perform an electrocoagulation reaction to remove fluoride ions in the wastewater. The distance between the anode and cathode plates is 1.5 cm, and the plate area of ​​the anode and cathode is 100 cm 2 , current density is 30mA / cm 2 The reaction time is 30 minutes. At this time, the fluoride ion concentration in the wastewater is below 5 mg / L. Then the electrodes are reversed. At this time, the titanium-based tin antimony oxide coated electrode is used as the anode and the aluminum-iron alloy electrode is used as the cathode for electro-oxidation reaction to remove the difficult-to-degrade organic matter in the wastewater. After 10 minutes of reaction, it enters the filtration device and is discharged after filtration. The fluoride ion and COD results of the effluent are listed in Table 2.

[0041] Example 4

[0042] It is used for electrochemical treatment of refractory organic matter in fluoride-containing wastewater. The method is as follows: 1L fluoride-containing wastewater 2 first enters the electrochemical reactor, turns on the power, uses the aluminum electrode as the anode, and the titanium-based ruthenium iridium oxide coating electrode as the cathode to perform an electrocoagulation reaction to remove fluoride ions in the wastewater. The distance between the anode and cathode plates is 2.0 cm, and the plate areas of the anode and cathode are both 100 cm 2 , current density is 25mA / cm 2 The reaction time is 20 minutes. At this time, the fluoride ion concentration in the wastewater is below 5 mg / L. Then the electrodes are reversed. At this time, the titanium-based ruthenium-iridium oxide coated electrode serves as the anode and the aluminum electrode serves as the cathode for electro-oxidation reaction to remove the difficult-to-degrade organic matter in the wastewater. After 25 minutes of reaction, it enters the filtration device and is discharged after filtration. The fluoride ion and COD results of the effluent are listed in Table 2.

[0043] Example 5

[0044] It is used for electrochemical treatment of refractory organic matter in fluoride-containing wastewater. The method is as follows: 1L fluoride-containing wastewater 2 first enters the electrochemical reactor, turns on the power, uses the iron electrode as the anode and the titanium-based lead dioxide electrode as the cathode to perform an electrocoagulation reaction to remove fluoride ions in the wastewater. The distance between the anode and cathode plates is 3.0 cm, and the plate area of ​​the anode and cathode is 100 cm 2 , current density is 20mA / cm 2The reaction time is 15 minutes. At this time, the fluoride ion concentration in the wastewater is below 5 mg / L. Then the poles are reversed. At this time, the titanium-based lead dioxide electrode is used as the anode and the iron electrode is used as the cathode for electro-oxidation reaction to remove the difficult-to-degrade organic matter in the wastewater. After 15 minutes of reaction, it enters the filtration device and is discharged after filtration. The fluoride ion and COD results of the effluent are listed in Table 2.

[0045] Table 2

[0046] Example <![CDATA[Effluent F - , mg / L]]> Outlet COD, mg / L Example 1 3.6 25.6 Example 2 3.3 26.1 Example 3 2.8 25.8 Example 4 3.1 26.7 Example 5 3.4 26.3

[0047] The Beijing Municipal Integrated Wastewater Discharge Standard stipulates that the COD discharge limit for discharge into surface water bodies is 30 mg / L. From the results in Table 2, it can be seen that the electrochemical treatment of fluorine-containing wastewater according to the method of the present invention can treat the organic matter in the wastewater to below 30 mg / L, meeting the Beijing Municipal Integrated Wastewater Discharge Standard.

[0048] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An electrochemical treatment method for fluorine-containing wastewater, characterized in that: The electrochemical treatment method comprises: the fluorine-containing wastewater enters an electrochemical reactor, an electro-flocculation reaction is carried out with a soluble metal electrode as an anode and a shape-stable electrode as a cathode to remove fluoride ions in the wastewater; then the electrodes are reversed, an electro-oxidation reaction is carried out with the shape-stable electrode as an anode and the soluble metal electrode as a cathode to remove refractory organic matter in the wastewater; finally, the wastewater after the electro-oxidation treatment enters a filtering device and is discharged after filtration.

2. The electrochemical treatment method according to claim 1, wherein: When the fluoride ion concentration in the wastewater after the electrocoagulation treatment reaches the electrochemical oxidation water inlet requirement, the electrode reversal is performed; preferably, when the fluoride ion concentration in the wastewater after the electrocoagulation treatment is below 5 mg / L, the electrode reversal is performed.

3. The electrochemical treatment method according to claim 1, wherein: The soluble metal electrode is an aluminum electrode, an iron electrode or an aluminum-iron alloy electrode.

4. The electrochemical treatment method according to claim 1, wherein: The shape-stable electrode is a titanium-based metal-coated oxide electrode or a boron-doped diamond film electrode; The metal coating oxide is preferably one or more of oxides of ruthenium, iridium, titanium, rhodium, tin, antimony, platinum and lead.

5. The electrochemical treatment method according to claim 1, wherein: The anode and cathode in the electrochemical reactor are one or more groups; When there are multiple groups of anodes and cathodes, the anodes and cathodes are arranged crosswise.

6. The electrochemical treatment method according to claim 1, wherein: The distance between the anode and cathode plates is 0.5-3.0 cm.

7. The electrochemical treatment method according to claim 1, wherein: The current density of the electrochemical reactor is 20-50 mA / cm 2 .

8. The electrochemical treatment method according to claim 1, wherein: The time of the electrocoagulation reaction and the electrochemical oxidation reaction are independently 10-30 minutes.

9. The electrochemical treatment method according to claim 1, wherein: The fluorine content in the fluorine-containing wastewater is 10-50 mg / L.

10. Use of the electrochemical treatment method according to any one of claims 1 to 9 in treating fluoride-containing wastewater.