Electrochemical treatment method and application of high-salt coal chemical wastewater

Abstract

The application belongs to the technical field of wastewater treatment, and discloses an electrochemical treatment method and application of high-salt coal chemical wastewater, which comprises the following steps: (1) injecting the high-salt coal chemical wastewater into an electrochemical reactor, and performing an electroflocculation reaction with a soluble metal electrode as an anode and a shape-stable electrode as a cathode, and meanwhile, the adsorption of a particle electrode is used to remove fluorine ions in the wastewater; (2) after the treatment in the step (1), the electrodes in the electrochemical reactor are reversed, an electrooxidation reaction is performed with the shape-stable electrode as the anode and the soluble metal electrode as the cathode, and meanwhile, the adsorption and electrooxidation degradation of the particle electrode are used to remove refractory organic matters in the wastewater; and (3) the wastewater treated in the step (2) is filtered in a filtering device, and then discharged. The method is simple in operation steps, small in occupied area, and suitable for treating the refractory organic matters in the high-salt coal chemical wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, and more particularly to an electrochemical treatment method and application of high-salt coal chemical wastewater. BACKGROUND

[0002] Coal chemical high-salt wastewater mainly comes from the drainage of chemical water stations, the drainage of circulating water systems, and the gasification wastewater formed in the coal gasification process, and the main pollutants are total dissolved solids (TDS) and refractory organic matter. The mass concentration of TDS is 10,000-100,000 mg / L, and even as high as 200,000 mg / L or more, and the mass concentration of COD is 100-5,000 mg / L. The COD composition is complex and the concentration is high, which may cause membrane pollution and bring difficulties to subsequent evaporation crystallization, such as serious foaming phenomenon, poor quality of crystalline salt, and inability to be reused, etc., limiting the further concentration or resource utilization of the wastewater. Therefore, before membrane treatment and subsequent evaporation crystallization, the organic matter in the high-salt wastewater must be removed. However, the current common water treatment technologies, such as activated carbon adsorption method and biological method, have the problems of high operating cost and inability to achieve the expected treatment effect for high-salt wastewater. Electro-catalytic oxidation has good removal effect on organic matter in wastewater, and the treatment process only has power consumption without reagent consumption, which is an ideal treatment method.

[0003] Coal chemical wastewater has complex composition and high COD concentration, and the fluorine ion concentration of gasification wastewater is high. Fluorine ions have a corrosive effect on the anode in electro-catalytic oxidation, which seriously affects the service life of the anode, so it is necessary to reduce the content of fluorine ions in water to meet the inlet requirements of electrochemical oxidation treatment. In the current water defluorination process technology, adsorption and coagulation sedimentation are more researched and applied, and coagulation sedimentation is one of the most commonly used process technologies for treating fluorine-containing wastewater. In addition, the current wastewater defluorination technology mainly treats medium and high concentration fluorine-containing wastewater, and it is relatively easy to achieve a fluorine concentration of ≤15 mg / L after treatment, but when the concentration is further reduced, the amount of chemicals increases and the difficulty increases. Therefore, it is necessary to develop a new technology for electrochemical treatment of refractory organic matter in high-salt coal chemical wastewater. SUMMARY

[0004] The application aims to provide an electrochemical treatment method and application of high-salt coal chemical industry wastewater, the high-salt coal chemical industry wastewater has high fluorine ion content and high sulfate content, the high sulfate content will affect the removal of fluorine ions, the treatment method removes most of the fluorine ions through the electrocoagulation reaction and the adsorption of particle electrodes, so that the fluorine ion concentration reaches the requirement of electrochemical oxidation of influent, and then the reverse electrode is used for electro-oxidation reaction, and the adsorption and electro-oxidation degradation of particle electrodes are used for treating refractory organic matter in the wastewater; the method has simple operation steps, small floor area, and is suitable for treating refractory organic matter in the high-salt coal chemical industry wastewater.

[0005] In order to achieve the above-mentioned purpose, one aspect of the application provides an electrochemical treatment method of high-salt coal chemical industry wastewater, the electrochemical treatment method comprises:

[0006] (1) injecting the high-salt coal chemical industry wastewater into an electrochemical reactor, using a soluble metal electrode as an anode and a shape-stable electrode as a cathode to perform electrocoagulation reaction, and cooperating with the adsorption of particle electrodes to remove fluorine ions in the wastewater;

[0007] (2) after the treatment of step (1), performing reverse electrode on the electrodes in the electrochemical reactor, using the shape-stable electrode as an anode and the soluble metal electrode as a cathode to perform electro-oxidation reaction, and cooperating with the adsorption and electro-oxidation degradation of the particle electrodes to remove refractory organic matter in the wastewater;

[0008] (3) making the wastewater treated in step (2) enter a filtering device, and discharging after filtration.

[0009] Another aspect of the application provides application of the above-mentioned electrochemical treatment method in treating high-salt coal chemical industry wastewater.

[0010] The technical scheme of the application has the following beneficial effects:

[0011] In the application, the electrocoagulation and electrochemical oxidation are arranged in the same electrochemical reactor, the anode and cathode of the electrode plate are converted through the conversion of the positive and negative poles of the power supply, the soluble metal electrode is used as the anode to remove fluorine ions in water through electrocoagulation, the particle electrode also has adsorption effect on the fluorine ions, the shape-stable electrode is used as the anode to treat refractory organic matter in the wastewater when the fluorine ion concentration reaches the requirement of electrochemical oxidation of influent, the particle electrode plays a role in adsorbing refractory organic matter on one hand, and effectively utilizes the electrolysis space on the other hand, and plays a role in strengthening the electric field, so that the organic matter in the wastewater can be treated through oxidation and degradation. The reverse electrode treatment of the two electrodes can prevent the occurrence of electrode passivation, and also plays a role in regenerating the particle electrode.

[0012] The device has the advantages of simple process, convenient operation, low energy consumption, no need to add reagent in the treatment process, low mud yield, no secondary pollution, and the ability to realize green and efficient treatment of refractory organic matters in high-salt coal chemical industry wastewater.

[0013] Other features and advantages of the present application will be described in detail in the following specific embodiments. DETAILED DESCRIPTION

[0014] The preferred embodiments of the present application will be described in more detail below. Although the preferred embodiments of the present application are described below, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein.

[0015] One aspect of the present application provides an electrochemical treatment method for high-salt coal chemical industry wastewater, comprising:

[0016] (1) injecting the high-salt coal chemical industry wastewater into an electrochemical reactor to perform electrocoagulation reaction with a soluble metal electrode as an anode and a shape-stable electrode as a cathode, while cooperating with the adsorption of a particle electrode to remove fluorine ions in the wastewater;

[0017] (2) after the treatment in step (1), reversing the electrodes in the electrochemical reactor to perform electrooxidation reaction with the shape-stable electrode as an anode and the soluble metal electrode as a cathode, while cooperating with the adsorption and electrooxidation degradation of the particle electrode to remove refractory organic matter in the wastewater;

[0018] (3) making the wastewater treated in step (2) enter a filtration device and being discharged after filtration.

[0019] In the present application, electrochemical flocculation and electrochemical oxidation treatment are performed in the same electrochemical reactor, which is simple in operation steps and small in floor area.

[0020] In the present application, the reversal of the electrodes is realized by switching the positive and negative poles of the power supply, i.e., switching the anode and cathode of the electrode plate. The switching of the positive and negative poles of the power supply can be realized manually or by setting automatic switching of the positive and negative poles of the power supply.

[0021] According to the present application, preferably, the reversal of the electrodes is performed when the fluorine ion concentration in the wastewater treated in step (1) reaches the requirement of electrochemical oxidation influent; further preferably, the reversal of the electrodes is performed when the fluorine ion concentration in the wastewater treated in step (1) is 5 mg / L or less.

[0022] According to the present application, preferably, the soluble metal electrode is an aluminum electrode, an iron electrode, or an aluminum-iron alloy electrode.

[0023] The shape-stable electrode is a titanium-based metal-coated oxide electrode or a boron-doped diamond film electrode; the metal-coated oxide is preferably one or more of oxides of ruthenium, iridium, titanium, rhodium, tin, antimony, platinum and lead;

[0024] The particle electrode is active alumina and / or active carbon.

[0025] According to the present application, preferably, the anode and the cathode in the electrochemical reactor are one or more groups;

[0026] When the anode and the cathode are one group, the particle electrode is arranged between the pole plates of the anode and the cathode;

[0027] When the anode and the cathode are multiple groups, the anode and the cathode are arranged in cross; the particle electrode is arranged between two adjacent pole plates.

[0028] According to the present application, preferably, the pole plate spacing of the anode and the cathode is 3.0-10.0 cm.

[0029] In the present application, preferably, when the anode and the cathode are multiple groups, the spacing between two adjacent pole plates is 3.0-10.0 cm.

[0030] According to the present application, preferably, the dosage of the particle electrode is 20-40 g / L.

[0031] In the present application, the dosage of the particle electrode is 20-40 g / L, which means that the dosage of the particle electrode is 20-40 g for 1 L of high-salt coal chemical industry wastewater.

[0032] According to the present application, preferably, the current density of the electrochemical reactor is 25-50 mA / cm 2 .

[0033] According to the present application, preferably, the time of the electrocoagulation reaction and the electrochemical oxidation reaction is independently 10-40 min.

[0034] In the present application, the time of the electrocoagulation reaction and the electrochemical oxidation reaction is adjusted according to the content of fluoride ions and the content of organic matter in the wastewater.

[0035] According to the present application, preferably, the content of fluoride in the high-salt coal chemical industry wastewater is 60-180 mg / L.

[0036] Another aspect of the present application provides the use of the above-mentioned electrochemical treatment method in treating high-salt coal chemical industry wastewater.

[0037] The present application will be described in detail below through examples.

[0038] The water quality of the high-salt coal chemical industry wastewater is shown in Table 1.

[0039] Table 1

[0040] wastewater Ca 2+ ]] total alkalinity Cl - ]] SO4 2- ]] pH conductivity F - ]]> COD 1 26.1 954 4473.7 17702.8 8.3 38.55 94.9 120 2 8.9 1180.4 3140.1 13791.1 9.0 35.96 154 105

[0041] Note: pH has no unit, conductivity unit is ms / cm, the rest units are mg / L, Ca 2+ , total alkalinity is calculated by CaCO3, same below. Ca 2+ represents calcium hardness, same below. The determination method of each parameter is as follows: Ca 2+ : refer to standard GB / T 6910-2006; total alkalinity: refer to standard GB / T 15451-2006; Cl - : refer to standard GB / T 15453-2008; SO4 2- : refer to standard GB / T 14642-2009; pH value: refer to standard GB / T 6920-1986; conductivity: refer to standard GB / T 6908-2008; F - : refer to standard GB / T 7484-1987; COD: refer to standard GB 11914-89.

[0042] In each of the following examples, an electrochemical reactor is provided with a cathode plate, an anode plate and a particle electrode, which is arranged between the cathode plate and the anode plate.

[0043] In each of the following examples, the concentration of F - is tested according to standard GB / T 7484-1987; the concentration of COD is tested according to standard GB 11914-89.

[0044] Example 1

[0045] For electrochemical treatment of refractory organic matter in high-salt coal chemical industry wastewater, the method is as follows: 1L of high-salt coal chemical industry wastewater 1 is injected into an electrochemical reactor, aluminum electrode is used as anode, and titanium-based ruthenium iridium titanium oxide coated electrode is used as cathode for electrocoagulation reaction, while cooperating with the adsorption of activated carbon particle electrode to remove fluoride ions in the wastewater, the dosage of particle electrode is 20g / L, the distance between anode and cathode is 3cm, and the area of anode and cathode is both 100cm 2 , the current density is 25mA / cm 2, the fluoride ion concentration in the wastewater is less than 5 mg / L; then, the electrodes are reversed, and the titanium-based ruthenium iridium titanium oxide coated electrode is used as the anode and the aluminum electrode is used as the cathode to perform electro-oxidation reaction for 30 min, while the adsorption of the activated carbon particle electrode and the electro-oxidation degradation of organic matter are combined to remove the refractory organic matter in the wastewater; finally, the treated wastewater enters the filtration device, and after filtration, it is discharged, and the fluoride ion and COD results of the effluent are listed in Table 2.

[0046] Example 2

[0047] The electrochemical treatment of refractory organic matter in high-salt coal chemical industry wastewater is as follows: 1 L of high-salt coal chemical industry wastewater 1 is injected into an electrochemical reactor, and an iron electrode is used as the anode and a titanium-based lead dioxide electrode is used as the cathode to perform electrocoagulation reaction, while the adsorption of the activated alumina particle electrode is combined to remove the fluoride ions in the wastewater, the particle electrode is added in an amount of 25 g / L, the distance between the anode and the cathode is 5 cm, and the area of the anode and the cathode is both 100 cm 2 , the current density is 30 mA / cm 2 , and the reaction time is 20 min, at which time the fluoride ion concentration in the wastewater is less than 5 mg / L; then, the electrodes are reversed, and the titanium-based lead dioxide electrode is used as the anode and the iron electrode is used as the cathode to perform electro-oxidation reaction for 20 min, while the adsorption of the activated carbon particle electrode and the electro-oxidation degradation of organic matter are combined to remove the refractory organic matter in the wastewater; finally, the treated wastewater enters the filtration device, and after filtration, it is discharged, and the fluoride ion and COD results of the effluent are listed in Table 2.

[0048] Example 3

[0049] The electrochemical treatment of refractory organic matter in high-salt coal chemical industry wastewater is as follows: 1 L of high-salt coal chemical industry wastewater 1 is injected into an electrochemical reactor, and an iron electrode is used as the anode and a titanium-based lead dioxide electrode is used as the cathode to perform electrocoagulation reaction, while the adsorption of the activated alumina particle electrode is combined to remove the fluoride ions in the wastewater, the particle electrode is added in an amount of 25 g / L, the distance between the anode and the cathode is 5 cm, and the area of the anode and the cathode is both 100 cm 2 , the current density is 30 mA / cm 2 , and the reaction time is 20 min, at which time the fluoride ion concentration in the wastewater is less than 5 mg / L; then, the electrodes are reversed, and the titanium-based lead dioxide electrode is used as the anode and the iron electrode is used as the cathode to perform electro-oxidation reaction for 20 min, while the adsorption of the activated carbon particle electrode and the electro-oxidation degradation of organic matter are combined to remove the refractory organic matter in the wastewater; finally, the treated wastewater enters the filtration device, and after filtration, it is discharged, and the fluoride ion and COD results of the effluent are listed in Table 2.

[0050] Example 4

[0051] The electrochemical treatment for the refractory organic matter in the high-salt coal chemical industry wastewater is as follows: 1L of the high-salt coal chemical industry wastewater 2 is injected into an electrochemical reactor, an aluminum electrode is used as an anode, and a titanium-based ruthenium iridium oxide coating electrode is used as a cathode to perform an electroflocculation reaction, while the adsorption of an activated alumina particle electrode is coordinated to remove fluoride ions in the wastewater, the particle electrode has a dosing amount of 35g / L, the plate spacing between the anode and the cathode is 10cm, and the plate area of the anode and the cathode is both 100cm 2 , the current density is 40mA / cm 2 , and the reaction time is 20min, at which time the fluoride ion concentration in the wastewater is less than 5mg / L; then, the electrodes are reversed, a titanium-based ruthenium iridium oxide coating electrode is used as an anode, and an aluminum electrode is used as a cathode to perform an electrooxidation reaction, the reaction time is 20min, while the adsorption and electrooxidation degradation of organic matter of an activated carbon particle electrode are coordinated to remove the refractory organic matter in the wastewater; finally, the treated wastewater enters a filtering device, is filtered and discharged, and the fluoride ion and COD results of the effluent are listed in Table 2.

[0052] Example 5

[0053] The electrochemical treatment for the refractory organic matter in the high-salt coal chemical industry wastewater is as follows: 1L of the high-salt coal chemical industry wastewater 2 is injected into an electrochemical reactor, an aluminum-iron alloy electrode is used as an anode, and a titanium-based lead dioxide electrode is used as a cathode to perform an electroflocculation reaction, while the adsorption of an activated alumina particle electrode is coordinated to remove fluoride ions in the wastewater, the particle electrode has a dosing amount of 40g / L, the plate spacing between the anode and the cathode is 6cm, and the plate area of the anode and the cathode is both 100cm 2 , the current density is 50mA / cm 2 , and the reaction time is 15min, at which time the fluoride ion concentration in the wastewater is less than 5mg / L; then, the electrodes are reversed, a titanium-based lead dioxide electrode is used as an anode, and an aluminum-iron alloy electrode is used as a cathode to perform an electrooxidation reaction, the reaction time is 15min, while the adsorption and electrooxidation degradation of organic matter of an activated carbon particle electrode are coordinated to remove the refractory organic matter in the wastewater; finally, the treated wastewater enters a filtering device, is filtered and discharged, and the fluoride ion and COD results of the effluent are listed in Table 2.

[0054] Table 2

[0055] example Water F - , mg / L effluent COD, mg / L example 1 3.8 24.0 example 2 3.1 23.5 example 3 2.9 23.8 example 4 3.3 26.9 example 5 3.5 25.1

[0056] The Beijing municipal integrated wastewater discharge standard stipulates that the COD discharge limit value for discharge into surface water bodies is 30 mg / L. As can be seen from the results in Table 2, the organic matter in the high-salinity coal chemical industry wastewater can be treated to below 30 mg / L by the method according to the present application, satisfying the Beijing municipal integrated wastewater discharge standard.

[0057] The above has described various embodiments of the present application, and the above description is exemplary, is not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An electrochemical treatment method for high-salinity coal chemical wastewater, characterized in that, The electrochemical treatment method includes: (1) The high-salt coal chemical wastewater is injected into an electrochemical reactor, and an electrocoagulation reaction is carried out with a soluble metal electrode as the anode and a stable electrode as the cathode. At the same time, the adsorption effect of the particle electrode is used to remove fluoride ions from the wastewater. (2) After the treatment in step (1), the electrodes are reversed in the electrochemical reactor, with the stable electrode as the anode and the soluble metal electrode as the cathode to carry out an electro-oxidation reaction. At the same time, the adsorption and electro-oxidation degradation of the particle electrode are combined to remove the recalcitrant organic matter in the wastewater. (3) The wastewater treated in step (2) is fed into a filtration device and discharged after filtration; When the fluoride ion concentration in the wastewater after step (1) is below 5 mg / L, the polarity is reversed. The particle electrode is activated alumina and / or activated carbon; the dosage of the particle electrode is 20-40 g / L. The current density of the electrochemical reactor is 25-50 mA / cm². 2 .

2. 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; The shape-stabilized electrode is a titanium-based metal-coated oxide electrode or a boron-doped diamond film electrode.

3. The electrochemical treatment method according to claim 2, wherein, The metal coating oxide is one or more oxides of ruthenium, iridium, titanium, rhodium, tin, antimony, platinum and lead.

4. The electrochemical treatment method according to claim 1, wherein, The anode and cathode in the electrochemical reactor are one or more sets; When the anode and cathode are a pair, the particle electrode is disposed between the plates of the anode and cathode; When there are multiple sets of anodes and cathodes, the anodes and cathodes are arranged in a cross pattern; the particle electrode is disposed between two adjacent electrode plates.

5. The electrochemical treatment method according to claim 1, wherein, The distance between the anode and cathode plates is 3.0-10.0 cm.

6. The electrochemical treatment method according to claim 1, wherein, The electrocoagulation reaction and the electrochemical oxidation reaction each have an independent time of 10-40 min.

7. The electrochemical treatment method according to claim 1, wherein, The fluoride content in the high-salinity coal chemical wastewater is 60-180 mg / L.